Water quality guidelines for public aquatic facilities

Water quality guidelines for public aquatic facilities — December 2019

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Water quality

guidelines for public

aquatic facilities

December 2019

Water quality guidelines for public aquatic facilities — December 2019

Page 2 of 70

Water quality guidelines for public

aquatic facilities - December 2019

Published by the State of Queensland

(Queensland Health), December 2019

This document is licensed under a Creative

Commons Attribution 3.0 Australia licence.

To view a copy of this licence, visit

creativecommons.org/licenses/by/3.0/au

You are free to copy, communicate and adapt the

work, as long as you attribute the State of

Queensland (Queensland Health).

For more information contact:

Water Unit, Department of Health,

Queensland Health, PO Box 2368,

Fortitude Valley BC QLD 4006,

email waterquality@health.qld.gov.au,

phone (07) 3328 9310.

An electronic version of this document is

available at www.health.qld.gov.au/public-

health/industry-

environment/environment-land-

water/water/quality/pool-spa-recreation.

Disclaimer:

The content presented in this publication is distributed by the Queensland Government as an information

source only. The State of Queensland makes no statements, representations or warranties about the

accuracy, completeness or reliability of any information contained in this publication. The State of

Queensland disclaims all responsibility and all liability (including without limitation for liability in

negligence) for all expenses, losses, damages and costs you might incur as a result of the information being

inaccurate or incomplete in any way, and for any reason reliance was placed on such information.

Water quality guidelines for public aquatic facilities — December 2019

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Contents

Chapter 1: Introduction 5

1.1 Purpose 5

1.2 Scope 6

1.3 Site-specific risk management plans 6

Chapter 2: Public health hazards associated with public aquatic facilities 8

2.1 Microbiological hazards 9

2.2 Chemical hazards 12

2.3 Environmental hazards 12

2.4 Water supply 12

Chapter 3: Regulatory framework 13

3.1 Public Health Act 2005 13

3.2 Links to local laws and other local government permits and contracts 14

3.3 Australian Pesticides and Veterinary Medicines Authority registered products 14

3.4 Australian Standards 14

Chapter 4: Treatment process 15

4.1 Filtration 16

4.2 Disinfection 18

4.3 Automatic chemical dosing 23

4.4 Disinfection by-products 23

4.5 Troubleshooting guide 24

Chapter 5: Bather numbers, water circulation and turnover times 25

5.1 Bather numbers 26

5.2 Water circulation 26

5.3 Turnover times 27

Chapter 6: Managing water balance 28

6.1 Langelier Saturation Index 28

Chapter 7: Monitoring 31

7.1 Operational monitoring 32

7.2 Verification monitoring 33

7.3 Record keeping 35

Chapter 8: Healthy swimming 36

8.1 Exclusion periods following illness 37

8.2 Showering 37

8.3 Toileting and handwashing 38

8.4 Changing nappies 38

8.5 Avoid swallowing pool water 38

8.6 Assistance animals 38

8.7 Signage 39

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8.8 Minimising the likelihood of environmental contamination 39

Chapter 9: Incident response 40

9.1 Response procedures 40

9.2 CT value 41

Chapter 10: Operator training 42

Appendices 43

Appendix 1: Interactive water features (splash pads, spray parks and water play areas) 43

Appendix 2: Water quality criteria and monitoring frequencies 47

Appendix 3: Troubleshooting guide 52

Appendix 4: Recommended turnover times 55

Appendix 5: Langelier Saturation Index 56

Appendix 6: Incident response 58

Appendix 7: Example monitoring log 63

Glossary 64

Reference material 69

Australian Standards 70

International Standard 70

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1.1 Purpose

While public aquatic facilities are vital for maintaining and promoting active lifestyles for

improved health and wellbeing, these facilities have been associated with outbreaks of

illness. Aquatic facility users, especially children, can be affected by disease-causing

microorganisms that are passed through contaminated pool water, contaminated surfaces or

through person-to-person contact.

This guideline assists organisations and people who operate public aquatic facilities to reduce

risks to public health. The focus of the guideline is on water quality associated risks and does

not consider risks related to pool design (e.g. hydraulics), physical safety (e.g. slips and falls),

drowning or sun protection. It can also provide advice to local and state government

environmental health officers to help fulfil their regulatory and advisory roles with respect to

water quality.

Chapter 1: Introduction

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1.2 Scope

The information and advice in this guideline apply to all public aquatic facilities. Public

aquatic facilities are those that are commonly used by the public.

They include but are not limited to:

• public swimming pools

and spa pools

• learn-to-swim pools

• school swimming pools

• aquatic facilities in gyms or

fitness centres

• some aquatic facilities associated with

apartment blocks, retirement

complexes and strata title and body

corporate developments

• aquatic facilities associated with

holiday accommodation, including

holiday parks, hotels, holiday

apartment complexes and motels

• water theme parks, with installations

such as water slides, wave simulators

and ‘lazy river’ pools

• hydrotherapy pools

• domestic pools when used for

commercial purposes (such as private

learn-to-swim classes).

• interactive water features

Specific information about interactive water features, also known as splash pads, spray

parks and water play areas, is included in Appendix 1.

Although this guideline may be useful to domestic swimming and spa pool owners,

questions about water quality or maintaining these pools are best directed to a pool shop

or pool contractor.

Organisations that manage natural bodies of water for recreational use should refer to the

latest edition of the National Health and Medical Research Council’s Guidelines for

managing risks in recreational water (refer to Reference material).

For operational matters not covered by this guideline, public aquatic facility operators should

refer to the Royal Life Saving Society Australia Guidelines for safe pool operations (refer to

Reference material). This is the recognised guidance document for pool managers to safely

operate aquatic facilities and includes guidance for facility design, risk management, safety

equipment, first aid, asset management, supervision and programs.

1.3 Site-specific risk management plans

Any public aquatic facility can use a site-specific risk management plan to help minimise

potential public health risks. All public aquatic facilities are encouraged to have such a

plan in place, however the use of risk management plans is particularly important for

high-risk facilities (refer to Table A2.4 Risk categories to inform monitoring frequencies

Risk Categories to inform monitoring frequencies in Appendix 2), where a facility cannot

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meet elements of this guideline, or where a facility falls outside the scope of this

guideline.

A site-specific risk management plan may include:

• a description of the facility, its source

water, and its treatment systems

• staff roles and responsibilities,

competency or training requirements

• water quality targets and treatment

objectives

• hazard identification

• risk assessment

• identification of control measures

• specific incident response procedures

• operational monitoring

• verification monitoring

• data recording and reporting

• stakeholder contact list.

Potential users of the aquatic facility, including any vulnerable groups such as children,

immune compromised, pregnant or elderly bathers should be considered in the risk

assessment. For example, an aged care or hospital aquatic facility may implement

additional controls such as increased frequency of verification monitoring to verify water

quality is within specification.

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Public aquatic facilities are important for maintaining and promoting active lifestyles.

Although using public aquatic facilities provides many health benefits, if aquatic facilities

are not properly managed, the health of bathers may be put at risk. This is particularly

relevant for vulnerable groups such as young children, the elderly and people with low

immunity.

Bathers can be affected by disease-causing microorganisms (pathogens) that are passed on

through contaminated pool water, contaminated surfaces or person-to-person contact.

Key points

• Poorly managed public aquatic facilities can create ideal conditions for

spreading disease.

• In public aquatic facilities, microbiological hazards pose the greatest risk to

health because they can cause outbreaks of disease.

• Chemicals can pose a risk to the health of bathers and staff.

Chapter 2: Public health hazards

associated with public aquatic facilities

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Similarly, certain chemicals can put the health of bathers at risk. This chapter provides

general guidance on the types of public health hazards that bathers can be exposed to in

public aquatic facilities.

2.1 Microbiological hazards

Microbiological hazards that can cause illness in humans include viruses, bacteria, protozoa

and fungi. In public aquatic facilities, microbiological hazards pose the greatest risk to

public health because they can cause outbreaks of illness.

Microbiological hazards are typically introduced into aquatic facilities through the following

sources:

• faecal matter– for example, from a contaminated water source, through faecal accidents,

or through shedding of faecal matter from bathers.

• other contaminants – for example, shedding from human skin, mucus, vomit or other

secretions, from animals, windblown matter, stormwater runoff, or natural inhabitants of

warm water environments (such as blue-green algae) that flourish if introduced into

poorly disinfected aquatic facilities.

Table 1 lists common illnesses related to microbiological hazards in public aquatic

facilities. Gastroenteritis and skin, wound and ear infections are the most common. Other

conditions such as respiratory illnesses caused by Legionella are less common and are

typically associated with poorly maintained spa pools. Illness caused by Acanthamoeba,

atypical Mycobacterium, Leptospira and Naegleria from aquatic facilities are uncommon,

with infrequent reports of illness in Australia or internationally.

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Table 1: Illnesses associated with aquatic facilities

Type of illness

Group of causal

microorganisms

Example of causal

microorganism

Example source of causal

microorganism

Gastroenteritis Virus

Norovirus Faecal accidents

Bather shedding

Vomit accidents

Hepatitis A

Adenovirus

Bacteria

Escherichia coli

(E. coli)

Shigella

Campylobacter

Protozoan

parasite

Cryptosporidium

Giardia

Skin, wound and ear

infections

Bacteria

Pseudomonas

aeruginosa

Bather shedding in water or

on wet surfaces

Staphylococcus

aureus

Virus

Molluscum

contagiosum

Bather shedding in water, wet

surfaces or swimming aids

Papillomavirus

(plantar wart)

Bather shedding in water or

wet surfaces, in particular on

changing room floors and in

showers

Varicella-zoster

virus (chickenpox)

Direct contact with infectious

fluid from an infectious

person such as sharing a

towel with an infectious

person

Fungi

Tinea pedis

(athlete’s foot)

Bather shedding on floors in

changing rooms, showers and

facility decks

Eye and nose

infections

Respiratory

infections

Virus

Adenovirus Faecal accidents (and nasal

and eye secretions)

Swimming pool

granuloma

Bacteria

Atypical

mycobacterium

Bather shedding in water and

on wet surfaces

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Type of illness

Group of causal

microorganisms

Example of causal

microorganism

Example source of causal

microorganism

Hypersensitivity

Pneumonitis

Aerosols from spas and water

sprays

Legionellosis

(Pontiac fever and

Legionnaires’

disease)

Bacteria

Legionella Aerosols from spas and water

sprays

Poorly maintained showers

Granulomatous

amoebic

encephalitis (GAE)

Keratitis

Protozoan

amoeba

Acanthamoeba Aerosols from spas

Bather shedding in water or

on wet surfaces

Wide ranging from

flu-like symptoms

to severe organ

disease

Bacteria

Leptospira Urine from infected animals

Primary amoebic

meningoencephalitis

(PAM)

Protozoan

amoeba

Naegleria fowleri Warm water environments

that are inadequately

disinfected

Biofilm in pipes and other

components in inadequately

disinfected waters

Adapted from: NSW Department of Health 2013-Public swimming pool and spa pool advisory document

The risk of passing on illness increases if the pool water is not properly managed. Of all the

microbiological hazards listed in Table 1, Cryptosporidium, the cause of the illness

cryptosporidiosis, is responsible for most outbreaks of illness associated with public aquatic

facilities. Cryptosporidium causes diarrhoea that, in some cases, can last up to 30 days.

Cryptosporidium is a problematic microbiological hazard in public aquatic facilities because

Cryptosporidium oocysts are much more resistant to chlorine disinfection than other

microbiological hazards. Also, a person affected by cryptosporidiosis can continue to have

Cryptosporidium oocysts in their faeces for several weeks after the symptoms have gone.

Therefore, an exclusion period of at least 14 days after all symptoms have ceased is

recommended to prevent potential contamination of a public aquatic facility.

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2.2 Chemical hazards

Chemical hazards can pose a risk to the health of bathers and staff. It is important that

chemicals are used and stored according to the manufacturer’s instructions. Personnel

who handle chemicals should be appropriately trained and wear the correct personal

protective equipment. Safety Data Sheets should be available onsite for all chemicals used

by a public aquatic facility.

Disinfection by-products can also pose health risks. Disinfection by-products are chemical

compounds that form when disinfection chemicals react with contaminants from the skin,

hair, sweat, saliva, urine and other organic matter. The most common disinfection by-

products associated with public aquatic facilities are chloramines and trihalomethanes.

Disinfection by-products pose a risk not only to water quality but also to air quality in indoor

facilities. To help ensure the health and comfort of bathers and staff, ventilation rates detailed

in the Building Code of Australia (Council of Australian Governments, 2016) and Australian

Standard 1668.2 should be followed for all indoor facilities.

2.3 Environmental hazards

Although bathers are mostly responsible for introducing contamination, it can also be

introduced from the surrounding environment and can vary seasonally. Environmental

contamination can be a particular problem for outdoor aquatic facilities where matter such

as dust, soil, sand, leaves and grass can easily enter the pool. Birds, bats and other animals

can also contaminate the pool with their droppings.

2.4 Water supply

The best available water supply, ideally mains drinking water, should always be used to fill a

pool. Roof-harvested rainwater could be used for pools provided it is introduced into the pool

through the balance tank to allow sufficient treatment. Recycled water, including treated

stormwater or sewage, is not suitable to use in swimming pools due to risks to human health

from microbiological and chemical contaminants.

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3.1 Public Health Act 2005

In Queensland, public health risks associated with public aquatic facilities are overseen by

local governments under the Public Health Act 2005 (the Act). The Act provides local

government environmental health officers with powers to help them determine whether

there is a public health risk at a public aquatic facility. The Act also provides enforcement

tools to address public health risks.

State Government environmental health officers may oversee the management of public

health risks associated with the use of State Government-owned or operated public aquatic

facilities. State Government environmental health officers may also provide advice in

response to an outbreak of disease that has occurred at any public aquatic facility or on the

remediation of a contaminated aquatic facility.

Key points

• The Public Health Act 2005 provides environmental health officers with powers

to manage public health risks associated with public aquatic facilities.

• Local governments may enact local laws about public aquatic facilities.

Chapter 3: Regulatory framework

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The Act does not require compliance with this guidance document. However, environmental

health officers may use it to help determine whether a public health risk exists and whether

public aquatic facilities are being appropriately managed.

3.2 Links to local laws and other local

government permits and contracts

Some Queensland local governments have enacted local laws regarding public aquatic

facilities under the Local Government Act 2009. These laws, in addition to conditions specified

on permits or in operational contracts, may specifically require aquatic facility operators to

comply with elements of this guideline that are suitable for compliance purposes. Public

aquatic facility operators should check with their local council to find out if there are any

relevant local laws in their local government area.

3.3 Australian Pesticides and Veterinary

Medicines Authority registered products

Swimming pool and spa chemicals sold in Australia are regulated under the Australian

Government’s Agricultural and Veterinary Chemicals Code Act 1994. The Australian

Pesticides and Veterinary Medicines Authority (APVMA) operates the Australian system that

evaluates, registers and regulates agricultural, veterinary and swimming pool chemicals.

This means that swimming pool and spa chemical products must be registered with the

APVMA before they can be sold to the leisure industry or to the general public.

The APVMA requires that spa and pool chemical suppliers and manufacturers show they

have followed a rigorous process before the product can be registered for use in Australia.

This process is described on the link to the APVMA website shown in the Reference material

section of this guideline.

Queensland Health only supports using primary disinfectants (as discussed in section 4.2.2)

that have been registered with the APVMA or have undergone independent testing against

the APVMA’s guidelines. The APVMA’s database of registered products can be searched via

the link to the APVMA website shown in the ‘Reference material’ section of this guideline.

3.4 Australian Standards

There are a number of Australian Standards that apply to public aquatic facilities. Where they

are relevant for a particular facility, the most recently published Australian Standards should

be complied with. A list of Australian Standards that apply to public aquatic facilities is

provided in the Reference material section of this guideline.

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Public aquatic facilities must maintain suitable water quality to prevent the spread of

illness. Facilities are expected to have effective treatment barriers in place to reduce harmful

microorganisms including viruses, bacteria and protozoan parasites. All public aquatic

facilities should adopt a multi-barrier approach which involves two or more types of

treatment processes to address pathogen risk. Each barrier (treatment process) on its own

Key points

• Aquatic facilities should adopt a multi-barrier approach to protect water

quality; this means there should be two or more types of treatment processes

to reduce pathogen risk.

• At a minimum, treatment processes must include filtration combined with

primary (chlorine- or bromine-based) disinfection.

• Secondary disinfection is recommended for all public aquatic facilities,

particularly for high-risk facilities where there is a need for extra protection

against Cryptosporidium.

Chapter 4: Treatment process

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may not be able to completely remove or prevent contamination, but together, the barriers

work to provide greater assurance that the water will be safe for use. Treatment processes

need to be operated, monitored and maintained in accordance with manufacturer’s

instructions to minimise variability in performance.

At a minimum, treatment processes should include filtration combined with primary

(chlorine- or bromine-based) disinfection. For facilities categorised as high-risk, additional

secondary disinfection such as ultraviolet (UV) disinfection or ozone is recommended to

reduce Cryptosporidium risk.

4.1 Filtration

In basic terms, filtration is a process of separating solids from liquids. In a public aquatic

facility, filtration is a treatment process that physically removes suspended particles from the

water. Effective filtration is an essential pre-treatment to effective disinfection.

Filters are often categorised according to their allowable operating flow rates. The flow rate

is a measure of how much water flows through each square metre of the filter medium’s

surface area per hour and is expressed as cubic metres per hour per square metre

/hr/m

), also described as the filtration flux (flowrate per unit area). Generally, the slower

the flow of water through the filter, the more efficiently it removes particles. Filters installed

at an aquatic facility will have a maximum operational flowrate, based on the flux suitable

for effective filtration.

New filtration systems should be designed to maximise the removal of Cryptosporidium.

Filters capable of removing particles 4 microns in diameter (refer to National Health and

Medical Research Council’s Australian Drinking Water Guidelines in Reference material) and

achieving a filtrate turbidity of no more than 0.5 NTU (Nephelometric Turbidity Units)

consistently will provide additional protection against Cryptosporidium.

For new aquatic facilities ultrafine precoat filters can achieve effective removal of

Cryptosporidium oocysts, when operated correctly, without the need for secondary

disinfection. However, facilities relying on conventional media filters should also employ a

secondary disinfection system (see 4.2.3).

Key points

• Effective filtration improves the efficacy of disinfection and is an essential

treatment step for protecting the health of public aquatic facility users.

• Filters capable of removing Cryptosporidium oocysts (4 microns in diameter)

reduce the risk of cryptosporidiosis in bathers.

• New filtration systems should be designed to maximise the removal of

Cryptosporidium.

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‘With chlorine-tolerant human pathogens like Cryptosporidium becoming

increasingly common in aquatic venues, effective filtration is a crucial process in

controlling waterborne disease transmission and protecting public health.'

World Health Organization 2006

Where a public aquatic facility has a number of different pools or water attractions, each water

body should ideally have its own filtration system. Independent filtration systems for each

water body provides the potential to isolate water bodies at higher risk of contamination from

lower risk pools, thereby allowing for some parts of the facility to remain open if only one

water body becomes contaminated. This is particularly important if pools are used by young

children who have not been toilet-trained.

Each filtration system should ideally have multiple filter units to allow backwashing of one

filter whilst maintaining filtration of the recirculating pool water. This flexibility also enables a

planned inspection and maintenance program, which is essential for filter efficiency.

Filtration types differ markedly in terms of the media, coagulant, process configuration and

the operational conditions applied. Each filter type should be operated in accordance with

the manufacturer’s specified operating parameters including filtration rates and run times,

head loss and backwash rates. The filter should be based on maximum bather numbers,

operating 24 hours per day.

The following processes make filtration more effective:

• Coagulation. Where a facility uses media filtration, the use of coagulants and flocculants,

when used in accordance with manufacturer’s instructions, can assist with the removal of

fine, dissolved, colloidal or suspended material, and most pathogens.

• Backwashing. Backwashing is the process of reversing the flow of water back through the

filters to flush trapped material to waste. Backwashing should take place whenever the

difference between the filter inlet pressure and the filter outlet pressure (differential

pressure, or pressure drop) reaches a level identified by the manufacturer or based on a

maximum filtration timeframe. Backwash water should always be sent to waste; the

concentration of contaminants in backwash water makes it unsuitable for re-use (without

advanced treatment).

• For media filters discard filtrate immediately following backwashing until the filtrate runs

clear. This will help minimise breakthrough of particulates following backwashing.

• Air scouring of media filters after backwash can significantly improve filter cleaning.

Cartridge filters must be removed and cleaned according to manufacturer’s instructions.

To monitor the efficacy of the filtration system, the operational monitoring program should

include monitoring of the coagulation dosing process, flowrate, filtration cycle including

filter-to-waste times, triggers for backwashing and turbidity.

Turbidity should be monitored immediately post filtration. The recommended limits for

turbidity are listed in Table A2.1 and Table A2.2 in Appendix 2.

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4.2 Disinfection

Effectively disinfecting the water in a public aquatic facility is the best way to protect the

health of bathers. Disinfection is the process of inactivating disease-causing

microorganisms through either physical destruction (e.g. by ultraviolet light) or by adding

specific disinfectant chemicals (e.g. ozone). Filtration of pool water is required to remove

particles and allow chemicals to directly contact microorganisms; therefore, disinfection

systems should be located post filtration and treat 100% of the filtration flow.

Not all disinfectants available on the market are fit for use in a public aquatic facility. Ideally

a disinfectant should:

• be able to inactivate all disease-causing microorganisms

• be fast-acting

• maintain lasting residual effectiveness

• be dosed easily, accurately and safely

• be non-toxic to humans at levels required for effective disinfection

• not cause damage to infrastructure

• be able to be measured accurately and simply on site.

In practice, no single disinfectant is able to meet all of these criteria completely.

The most suitable type of disinfectant will depend on a range of factors including:

Key points

• Chlorine- and bromine-based disinfectants are the only chemical-based

disinfectants acceptable for use in public aquatic facilities for primary disinfection.

• Recommended disinfectant residuals (concentrations) should be maintained at all

times.

• Automatic dosing is recommended for all facilities for consistent and reliable dosing.

• Automatic dosing enables the operator to respond to variables, such as bather

numbers and weather conditions, that can modify dosing requirements.

• Secondary disinfection is recommended for all public aquatic facilities, particularly

for high-risk facilities where there is a need for extra protection against

Cryptosporidium.

• Secondary disinfection should be designed to achieve a minimum 99.9% inactivation

of Cryptosporidium oocysts as water passes through the disinfection system.

• Pool circulation systems should have adequate water turnover to ensure disinfected

water is present in all parts of the aquatic facility.

• Operators of public aquatic facilities should implement proactive strategies to

manage disinfection by-products.

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• indoor or outdoor situation

• the type of aquatic facility – such as general pool or specialised hydrotherapy

• the chemical characteristics of the water supply

• the number of people who use the facility

• circulation capacity and pool design

• chemical handling and safety issues

• supervision and maintenance requirements

• pool water temperatures.

4.2.1 Types of disinfectants

In this guideline, disinfectants are categorised as either ‘primary’ or ‘secondary’

disinfectants. Primary disinfectants must not only be capable of killing hazardous

microorganisms, but they must also persist in the water to provide ongoing disinfection.

They provide the greatest overall level of disinfection and should therefore be used at all

public aquatic facilities. As mentioned in Chapter 3, in Australia the APVMA assesses primary

disinfectants for their effectiveness and safety.

At the time of publication, the only primary disinfectants registered by the APVMA and

acceptable to use in public aquatic facilities, are specific compounds that are chlorine- or

bromine-based. These disinfectants are generally effective at inactivating viruses and bacteria

that can cause disease. However, neither chlorine nor bromine is effective against

Cryptosporidium at levels that are acceptable for general use when the pool is operational.

Secondary disinfectants generally boost or support primary disinfection and are

recommended for all facilities, particularly for high risk facilities (refer to Table A2.4 in

Appendix 2) where there is a need for extra protection against Cryptosporidium. Commonly

accepted secondary disinfection systems include ozone and UV disinfection systems.

4.2.2 Primary disinfectants

4.2.2.1 Chlorine-based disinfectants

[Refer to Table A2.1 in Appendix 2 for the chemical criteria for facilities using chlorine-based disinfectants.]

Chlorine is the most common primary disinfectant and is generally effective at inactivating

viruses and bacteria that can cause disease. Chlorine is not effective against certain

protozoa such as Cryptosporidium at levels that are acceptable for regular use.

Approved chlorine-based chemicals include:

• elemental chlorine gas

• liquid chlorine (sodium hypochlorite)

• granular chlorine (calcium and lithium hypochlorite)

• electrolytic generation of chlorine from salt (salt chlorination)

• stabilised chlorine granules/tablets (dichloroisocyanurate and trichloroisocyanurate).

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The concentration of stock chlorine solutions can degrade quickly with improper storage. As

with all chemicals, chlorine should be stored in accordance with the label instructions.

When chlorine is added to water it forms a mixture of hypochlorous acid (a strong

disinfectant) and hypochlorite ions (a weaker disinfectant). Together, hypochlorous acid and

hypochlorite ion make up what is known as ‘free chlorine’.

The pH of the water will affect how much of the stronger disinfectant (hypochlorous acid) is

formed. To ensure free chlorine remains effective, pH is recommended to be maintained

within the range listed in Table A2.1 in Appendix 2. If the pH drops too low, it may affect bather

comfort; if it becomes too high the free chlorine will lose most of its disinfection power.

Free chlorine can react with nitrogen-containing contaminants in the water, such as

ammonia, to form ‘combined chlorine’ or ‘chloramine’. Combined chlorine is unwanted

because it is not only a poor disinfectant, but it can also cause skin irritation, eye irritation,

corrosion and a strong and offensive ‘chlorine smell’.

When added together, free and combined chlorine is called ‘total chlorine’. When

evaluating total chlorine values, the combined chlorine value should not exceed the level

stated in Table A2.1 in Appendix 2.

Chlorine demand

Chlorine demand reflects the amount of free chlorine that is lost or used up through reactions

with microorganisms and other contaminants in the water; it is the difference between the

amount of chlorine added to the water and the amount of free available chlorine or combined

chlorine remaining at the end of a specified time period. Chlorine demand is often relative to

the number of bathers but is ultimately related to the total amount of contaminants in the

water (leaves, dirt, cosmetics, sunscreen etc.). The greater the chlorine demand, the greater

the amount of chlorine that will need to be added to the water to ensure the minimum

recommended free chlorine level is maintained at all times. Chlorine demand can be reduced

by encouraging bathers to shower before they enter the water and designing public aquatic

facilities such that environmental contamination is minimised.

Stabilised chlorine

In outdoor facilities sunlight breaks down chlorine, which can lead to significant loses of

free chlorine. Stabilised chlorine (chlorine with cyanuric acid added to it) can be used to

address this issue because cyanuric acid bonds loosely to the free chlorine to minimise

the impact of UV light. It can be purchased as granules/tablets or can be formed by adding

cyanuric acid to water containing free chlorine.

The decision to use stabilised chlorine in an outdoor aquatic facility and the level at which it

is added should be balanced against the need for immediate remediation in the event of a

diarrhoeal incident or Cryptosporidium contamination incident (refer to Appendix 6). Use of

stabilised chlorine can affect the effectiveness of hyperchlorination procedures. For

hyperchlorination to be undertaken, cyanuric acid concentration levels need to be dropped

below 15 mg/L. This may involve partially draining the pool and adding fresh water.

The maximum level of cyanuric acid that is recommended to be added to an outdoor pool is

detailed in Table A2.1 in Appendix 2. Cyanuric acid reduces the disinfection power of

hypochlorous acid, therefore the minimum free chlorine level should be maintained at the

level listed in Table A2.1 in Appendix 2. Cyanuric acid should not be used in indoor pools.

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4.2.2.2 Bromine-based disinfectants

[Refer to Table A2.2 in Appendix 2 for the chemical criteria for facilities using bromine-based primary

disinfectants.]

Bromine is another primary disinfectant that works in a similar way to chlorine. Bromine-

based chemicals include:

• bromo-chloro-dimethylhydantoin (BCDMH) tablets

• sodium bromide with an activator (hypochlorite or ozone).

Bromine is more stable at higher temperatures than chlorine but slightly less effective as a

disinfectant, therefore the minimum concentrations must be higher. Bromine is commonly

used in spa pools but, because it will decay in sunlight and cannot be stabilised, is rarely

used in larger outdoor aquatic facilities.

The effectiveness of bromine is also affected by pH but to a lesser extent than for chlorine.

To ensure bromine remains effective, pH should be maintained within the range detailed in

Table A2.2 in Appendix 2.

Bather contact with brominated pool water can lead to skin issues such as itching and

rashes. However, skin irritation is less likely to occur in properly maintained facilities where

the right water balance is maintained and where regularly exchanging water prevents a

build-up of disinfection by-products and other chemicals.

4.2.3 Secondary disinfectants

Secondary disinfection is recommended for all new high-risk public aquatic facilities (refer

to Table A2.4 in Appendix 2) on the basis of the need for extra protection against

Cryptosporidium.

4.2.3.1 Ultraviolet disinfection

UV disinfection has a higher energy than visible light but, because it has a shorter

wavelength, it is invisible to the human eye. UV light is a powerful secondary disinfectant,

particularly against bacteria and protozoa such as Cryptosporidium. The germicidal

wavelength of UV light kills or inactivates these microorganisms by destroying the nucleic

acid inside them. However, because no lasting disinfection residual can be provided, UV light

is not considered a primary disinfectant.

UV disinfection systems should be designed for full flow (not side stream) to achieve a

minimum 99.9%, inactivation of Cryptosporidium for interactive water features (splash pads,

spray parks and water play areas) and a minimum 99%, reduction for all other types of facility

(Centers for Disease Control and Prevention, 2018).

UV disinfection systems typically have one or more UV lamps installed in the pipework

where the pool water circulates. The ‘sleeves’ that protect the UV lamps must be cleaned

regularly so the lamps continue to emit the correct dose. The clarity and flow rate of the

water can also impact the effectiveness of UV lamps, therefore the operational limits set by

the manufacturer should be complied with. Some UV disinfection systems have self-cleaning

lamp sleeves and provide for real-time monitoring of the dose rate.

Water quality guidelines for public aquatic facilities - December 2019 Page 22 of 70

The maximum and minimum levels required for chlorine and bromine remain the same

when using UV disinfection. UV disinfection systems should be positioned before any

chlorine or bromine dosing points because the UV light can reduce the concentration of

disinfectant residual in the water.

4.2.3.2 Ozone

Ozone is a highly reactive gas that can be dissolved in water. When dissolved in water, it acts

as a powerful disinfectant that can inactivate a wide range of disease-causing

microorganisms. Ozone is not considered a primary disinfectant because no lasting residual

can be provided.

Ozone is typically used with chlorine as a secondary disinfectant. It provides greater

disinfection power and can inactivate Cryptosporidium oocysts. Ozone systems should be

designed to achieve a 99.9%, reduction of Cryptosporidium for interactive water features

(splash pads, spray parks and water play areas) and a minimum 99%, reduction for all other

types of facility (Centers for Disease Control and Prevention, 2018).

When ozone returns to its gaseous form, it can cause respiratory irritation. Therefore,

where ozone is used as part of the water treatment system it must be removed from the

water (‘quenched’) before the water is returned to the part of the facility where bathers are

exposed. The treatment systems should include an activated carbon bed or ozone

destructor for quenching ozone before the treated water is returned to the area where

people are using the water. Owing to the safety hazard from ozone, a breakthrough ORP

(oxidation reduction potential) sensor should be installed after the carbon filter to shut

down and raise an alarm if ozone is detected after the filter.

The maximum and minimum levels required for chlorine should be maintained when using

ozone. Ozone systems should be located before any chlorine dosing points because the

activated carbon bed or ozone destructor will also remove any chlorine in the water.

Avoid the use of ozone with BCDMH because it may produce bromate,

a harmful disinfection by-product.

4.2.3.3 Chlorine dioxide

Unlike chlorine-based disinfectants, chlorine dioxide is not a form of primary disinfection

because it does not produce free chlorine. Chlorine dioxide is a powerful disinfectant;

however, it is more complex to dose consistently compared with chlorine and bromine.

Some public aquatic facilities may use chlorine dioxide as a supplementary ‘shock

treatment’ to manage health risks associated with Cryptosporidium and Giardia or the

build-up of biofilm. If the chlorine dioxide manufacturer has validated the treatment

efficacy, some facilities may choose to use chlorine dioxide for managing chloramine

concentrations or in response to faecal contamination incidents.

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4.3 Automatic chemical dosing

Automatic dosing of primary disinfectants is strongly recommended for all public aquatic

facilities. Automatic dosing systems can be programmed with a set range of values that

ensure optimal disinfection. Automatic dosing systems will range in complexity but, at a

minimum, all dosing systems should be operated to ensure chemicals are dosed within the

operational set point range to ensure the appropriate disinfectant residual is maintained at

all times More advanced automatic dosing systems allow for ‘proportional dosing’ whereby

the dose rate varies according to the magnitude of the deviation from the set point.

4.4 Disinfection by-products

Disinfection by-products are unwanted chemical compounds that form when disinfection

chemicals react with organic matter in the water, including contaminants from skin, hair,

sweat, saliva and urine. The most common disinfection by-products associated with public

aquatic facilities are chloramines and trihalomethanes. Public health risks from

disinfection by-products in aquatic facilities are likely to be low. By contrast,

microbiological risks are significant if disinfection is inadequate. At no time should

disinfection be compromised or reduced over concerns relating to disinfection by-

products.

4.4.1 Chloramines

Chlorine reacts with certain nitrogen-containing compounds introduced by bathers (mostly

urine and sweat) to form chloramines (also known as ‘combined chlorine’). Chloramines can

cause skin and eye irritation and have a strong smell that bathers often incorrectly associate

with high levels of chlorine.

Chloramines can also affect air quality in indoor venues. As such, adequate ventilation is

essential. Specific advice on controlling the air quality impacts of chloramines in indoor

facilities is contained in the NSW Department of Health’s (2013) fact sheet Controlling

chloramines in indoor swimming pools (refer to Reference material).

Reducing the amount of nitrogen-containing compounds introduced into the water will help

to reduce the rate at which chloramines are produced. Requiring bathers to shower with

soap and rinse well before swimming or entering the water, and strongly encouraging regular

toilet breaks, can help achieve this.

Chloramines can be controlled with secondary disinfection systems such as medium pressure

UV disinfection and ozone. Alternatively, breakpoint chlorination or oxidisers - such as

hydrogen peroxide, chlorine dioxide and potassium monopersulphate - can be used.

Breakpoint chlorination is a process where enough chlorine is added to a pool to oxidise

chloramines in the water to ensure an effective free chlorine residual is produced.

Chloramines can also be controlled in public aquatic facilities by regular shock dosing of

chlorine to a concentration of at least 10 times the combined chlorine concentration. To

prevent harm, shock dosing must only occur when the facility is closed. The facility should not

be reopened until the total chlorine level is less than 10 mg/L. In instances where shock

dosing does not remove or reduce chloramines, replacing a proportion of the facility’s water

with fresh water can reduce the level of chloramines present.

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4.4.2 Brominated disinfection by-product

Bromine can react with certain organic chemicals to form brominated disinfection by-

products. Reducing the amount of organic chemicals introduced into the water will help to

reduce the rate at which brominated disinfection by-products are produced. Requiring

bathers to shower with soap and rinse well before swimming or entering the water, and

strongly encouraging regular toilet breaks, can help achieve this.

4.4.3 Trihalomethanes

Trihalomethanes are produced when chlorine- and bromine-based disinfectants react with

organic matter that is introduced by bathers, the surrounding environment, or is present in

source water. While long term exposure to elevated levels of trihalomethanes may be

hazardous to human health, in a well-managed aquatic facility they are unlikely to be a

significant health risk.

‘The risks from exposure to chlorination by-products in reasonably well managed

swimming pools would be considered to be small and must be set against the

benefits of aerobic exercise and the risks of infectious disease in the absence of

disinfection.’

– World Health Organization 2006

Like chloramines and brominated disinfection by-products, the level of trihalomethanes

can be minimised by getting bathers to shower using soap and rinse thoroughly before

they enter the water.

4.5 Troubleshooting guide

Many variables can affect public aquatic facility treatment systems. Common issues have

been summarised in the troubleshooting guide in Appendix 3. The information provided

should be used as a guide only. There may be other causes that are not listed. Misdiagnosis

or inappropriate action can worsen some problems to a point where the safety of bathers

and staff is at risk. Only suitably qualified or experienced staff should diagnose or

undertake corrective actions. If you are unsure, it is best to seek professional advice.

Water quality guidelines for public aquatic facilities - December 2019 Page 25 of 70

Key points

• A facility should strike a realistic balance between the number of bathers it

allows and the capacity of the facility and treatment plant.

• Effective water circulation ensures treated water reaches all areas of the

facility and that polluted water is removed efficiently.

• Short turnover times, in combination with filters that are capable of removing

Cryptosporidium and/or secondary disinfection systems that are capable of

inactivating Cryptosporidium, provide the highest level of protection.

Chapter 5: Bather numbers, water

circulation and turnover times

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5.1 Bather numbers

Working out the maximum number of bathers that a facility can accommodate should take

into account a number of factors including the surface area of water in the facility, the water

depth, the type of activity and the capability of the water treatment plant.

The maximum bather numbers for a facility should be recorded and pool managers should

ensure systems are in place so that the maximum bather number is not exceeded.

Where entrance to the facility cannot be controlled, the issue of bather numbers should be

addressed in a facility risk management plan.

The maximum bather numbers should be reviewed regularly to determine whether the

treatment system is capable of maintaining the water quality. If the maximum bather

number is approached or exceeded, then operators may need to:

• implement strategies to reduce bather numbers (e.g. by sectioning off parts of the pool)

• increase the treatment plant capability

• further dilute the pool water with fresh water

• use additional treatment such as ozone or UV disinfection.

5.2 Water circulation

Efficient water circulation in a public aquatic facility is very important because it ensures

pollutants are adequately removed as quickly as practicable and that treated water reaches

all areas of the facility.

Ideally the majority of pool water should be taken from the surface of the pool because it

contains the highest concentration of pollutants. The remainder should be drawn from the

bottom to remove grit and other matter that accumulates on the floor. Undertaking a dye

test is a reliable way of assessing water circulation and should be conducted during

commissioning of a new facility and repeated following any changes to the filtration or

hydraulic system as well as routinely to ensure water circulation remains effective. A

procedure for undertaking dye tests is detailed in the Water Circulation Dye Test (Centers for

Disease Control and Prevention, 2016).

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5.3 Turnover times

Turnover time is the time taken for a quantity of water that is equal to the volume of water

in the aquatic facility to pass through the filtration system.

Facilities with high bather numbers and low volumes of water (such as shallow wading pools

and spas) require short turnover times, so that water is circulated through the treatment

process more frequently. This is due to the potential for higher contaminant loads in the

water. Facilities with low bather numbers and high volumes of water (such as diving pools)

can use longer turnover times.

A shorter turnover time means there is less time between when contaminants are

introduced into the water and when that water passes through the facility’s water treatment

plant. Using a secondary disinfection system, or a filter that is capable of removing

Cryptosporidium, means the risk to bathers is reduced. This is the basis of the worldwide

trend to decrease the turnover time for public aquatic facilities.

A public aquatic facility operator may have limited control over the turnover time for an

existing water treatment system. However, when retrofitting or upgrading an existing pool, or

constructing a new public aquatic facility, site-specific turnover times should be adopted,

and the inlets and outlets should be positioned so they provide the best water circulation

and contaminant removal. The NSW Department of Health 2013 - Public swimming pool and

spa pool advisory document (Chapter 7) and the Pool Water Treatment Advisory Group 2017 -

Swimming pool water – treatment and quality standards for pools and spas (Chapter 6) both

contain acceptable approaches for calculating site-specific turnover times.

If site-specific calculations are not used to determine turnover times, some recommended

times for different types of public aquatic facilities are shown in Table A4.1 in Appendix 4.

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Water balance is about pool water chemistry and how different physicochemical parameters

interact. These parameters include pH, total alkalinity, calcium hardness, total dissolved

solids and temperature. Water that is not well balanced can affect disinfection, can be

uncomfortable for bathers and can result in scale forming or fittings corroding.

6.1 Langelier Saturation Index

The most common method for checking the balance of water is the Langelier Saturation

Index (LSI). The LSI is a mathematical equation that relates to each of the parameters

Key points

• Appropriately balanced water is essential for effective disinfection, bather

comfort and protecting the aquatic facility’s infrastructure.

• The most common method for checking the water balance is to use the

Langelier Saturation Index, which takes account of the water’s pH, total

alkalinity, calcium hardness, total dissolved solids and temperature.

Chapter 6: Managing water balance

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described below. This equation is described in detail in Appendix 5. The LSI should always

be within the acceptable range (refer to Table A5. 1 in Appendix 5).

6.1.1 pH

The pH of water is a measure of how acidic or alkaline the water is. The pH of water in all

aquatic facilities should be maintained within the recommended range (refer to Table A2.1

(chlorinated facilities) and Table A2.2 (brominated facilities) in Appendix 2) to ensure

effective disinfection and bather comfort.

If the pH is too high, it can be reduced by adding strong acids such as hydrochloric

(muriatic) acid or sodium bisulphate (dry acid). Acid should always be diluted into water

before being added slowly to the balance tank. Lowering the pH also lowers total

alkalinity, so take care when adding acid to ensure the water stays in balance. Carbon

dioxide can also be used to lower pH but, because it is a weak acid, the pH change will be

slower than when using strong acids.

If the pH is too low, sodium carbonate (soda ash) can be used to raise it quickly. Sodium

bicarbonate (bicarb soda) can be used to raise pH more slowly. Increasing the pH in this way

also increases total alkalinity.

Automatic pH control is recommended for all public aquatic facilities and strongly

recommended for high-risk facilities (refer to Table A2.4 in Appendix 2 for further

information on aquatic facility risk categories).

6.1.2 Total alkalinity

Total alkalinity is a measure of the ability of water to withstand changes to pH (also referred

to as its buffering capacity). Total alkalinity should be maintained within the recommended

range (refer to Table A2.1 (chlorinated facilities) and Table A2.2 (brominated facilities) in

Appendix 2).

If the total alkalinity is too low, the pH can change rapidly. If the total alkalinity is too high,

it will be difficult to adjust the pH. Total alkalinity can be reduced by adding strong acids

or raised by adding chemicals such as bicarb soda, though adding these chemicals will

also affect pH.

6.1.3 Calcium hardness

Calcium hardness is the amount of calcium dissolved in the water. Balanced water should

contain enough calcium so the water does not damage concrete surfaces or tile grout but

not so much that it causes scale to form.

If calcium hardness needs to be raised, it can be increased by adding calcium chloride. If it

needs to be reduced, it can be reduced by draining some water from the aquatic facility and

introducing make-up water containing lower levels of calcium hardness.

6.1.4 Total dissolved solids

Total dissolved solids (TDS) describes the amount of salts and the small amounts of organic

matter dissolved in water.

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The level of TDS in water increases over time as bathers introduce contaminants or when

water treatment chemicals are added. In general, TDS is managed by exchanging facility

water with fresh make-up water. In a well-designed and well-operated aquatic facility, with

regular backwash and routine exchange of water, TDS should not be a significant problem.

6.1.5 Temperature

The temperature of the water will affect its balance, although it is the least important of the

water balance factors. Higher water temperatures can increase bacterial growth in the water,

increase scaling and also affect the comfort of bathers. The temperature of any swimming or

spa pool should not exceed 40°C.

It is important to consider how temperature may vary throughout the diurnal period and

within the swimming or spa pool. Consideration should be given to when and where

temperature is measured to ensure representative results. Locally warmer or cooler parts of

the pool (e.g. near lamps or heaters or after cooler water has topped up the pool or heaters

have been off for some time) should be considered when measuring water temperature.

Samples should be taken, or temperature monitoring devices installed and monitored, to

capture the warmest temperatures experienced in the pool during its use.

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Monitoring public aquatic facilities helps ensure the water quality is maintained. There are

two types of monitoring: operational and verification.

Operational monitoring involves monitoring the performance of treatment processes or

physical variables like water temperature. This could involve manual or automated

operational monitoring to ensure that they are operating within the operational limits.

Operational monitoring provides pool operators with an opportunity to address water

quality immediately. It should be the focus of monitoring activities.

Alternatively, verification monitoring usually involves sending a water sample to a laboratory

to verify that the water quality criteria have been met.

Key points

• Operational monitoring should be the main focus for monitoring activities.

• Automated operational monitoring is recommended for all public aquatic

facilities and strongly recommended for high-risk facilities.

Chapter 7: Monitoring

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7.1 Operational monitoring

Operational monitoring includes any automated or manual monitoring of chemical and

physicochemical parameters (for example, concentration of primary disinfectant, pH and

temperature) and is essential for all public aquatic facilities.

Facility operators need to test the water regularly to check that the water treatment systems

are operating as expected. Automated operational monitoring provides for more frequent or

even ‘real time’ monitoring and is therefore the better option for operational monitoring.

Manual operational monitoring provides the next best method for determining whether the

treatment systems are operating as they should.

7.1.1 Automated operational monitoring

Automated operational monitoring (sometimes called ‘online monitoring’) usually involves

use of monitoring probes or instruments to provide real-time information about water

quality parameters. These probes require periodic calibration against standard solutions or

‘calibration standards’. Automated operational monitoring is needed when automatic dosing

systems are used (such as automatic chlorine dosing) but may also be used to monitor other

water quality parameters or treatment steps. Where possible, treatment processes should

have on-line instrumentation to monitor their performance and trigger alarms and

corrective actions to ensure that they are operating within specification and in accordance

with the manufacturer’s recommendations.

Online instrumentation for filtration systems may include coagulant dosing control, online

filtrate turbidity, pressure differential and flowrate; for ultraviolet disinfection systems,

ultraviolet transmissivity, flowrate, UV lamp age, UV lamp sensor; and for chlorination systems

chlorine setpoint dose, chlorine residual monitoring, pH and temperature. Where automated

operational monitoring is used, the results should be recorded electronically. The automated

monitoring system should be configured to alert facility operators whenever operational

parameters are not within acceptable limits.

Where automated operational monitoring is used, regular manual operational monitoring

should also be used to confirm that the results from the automated systems are accurate.

These samples should be taken from a location just before the monitoring probes.

7.1.2 Manual operational monitoring

Manual operational monitoring provides spot checks of chemical and physicochemical

parameters. Manual samples should be taken from a location furthest from the inlets

where bathers have not been present for the previous 60 seconds. Taking samples for

ozone is an exception; these samples should be taken close to an inlet to confirm ozone is

being removed or ‘quenched’.

7.1.3 Test kits

All aquatic facilities should use appropriately calibrated photometers for manual

operational monitoring. Domestic pool kits and test strips are not recommended for public

aquatic facilities because they are not accurate.

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7.1.4 Frequency of operational monitoring

All aquatic facilities should ensure disinfectant residual, pH and water balance (alkalinity,

calcium hardness and TDS) are monitored regularly. Higher risk facilities should be

monitored more frequently than lower risk facilities. Table A2.4 in Appendix 2 provides

guidance on risk categories for public aquatic facilities. Table A2.5 in Appendix 2 provides

recommended operational monitoring frequencies for each risk category.

7.2 Verification monitoring

Verification monitoring checks that the required water quality criteria have been met.

Verification monitoring typically involves taking a water sample and sending it to an

external laboratory for analysis.

Verification monitoring usually focuses on microbiological parameters but can also include

certain chemical criteria that cannot be easily analysed by pool operators.

7.2.1 Microbiological parameters

Microbiological parameters that should be included in a verification monitoring program for

aquatic facilities include heterotrophic colony count (HCC), Escherichia coli and

Pseudomonas aeruginosa. Guideline values for each of these parameters are provided in

Table A2.3 in Appendix 2.

7.2.1.1 Heterotrophic colony count

HCC, sometimes referred to as ‘heterotrophic plate count’ or ‘total plate count’, provides a

basic indication of the microbiological quality of a water sample. HCC does not

differentiate between harmless and potentially harmful bacteria; it provides a simple

indication of the number of bacteria present in the water. However, it can also provide

important information that can help determine whether the filtration and disinfection

processes are operating effectively.

Elevated HCC results suggest disinfection systems are not operating as required and so the

performance of the treatment processes should be checked. If a treatment deficiency is

found, actions should be taken to correct it (refer to Appendix 6). If no treatment deficiencies

are found, a resample should be taken to verify there are no ongoing issues. If ongoing

issues are found, the treatment process and/or management of the aquatic facility may

need to be improved, e.g. through enhancing cleaning, water chemistry, water turnover,

reducing bather numbers or treatment upgrades.

7.2.1.2 Escherichia coli

E. coli is a bacterium found in large numbers in the faeces of warm-blooded mammals. Most

strains of E. coli are harmless, but some can cause serious illness in humans. E. coli is

typically used as an indicator of faecal contamination and its presence in water suggests

that filtration and disinfection may not have been effective and therefore disease-causing

microorganisms may also be present.

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Where a laboratory does not analyse for E. coli, samples may be submitted for

thermotolerant coliform analysis because these are the next best indicator of faecal

contamination. A noncompliant E. coli or thermotolerant coliforms result indicates

deficiencies in disinfection and this should trigger an investigation into the performance of

the treatment process. If a treatment deficiency is found, appropriate remedial action will

need to be taken (refer to Appendix 6) and a resample taken to verify the effectiveness of the

remedial action. If no treatment deficiencies are found, a resample should be taken anyway

to verify there are no ongoing issues.

7.2.1.3 Pseudomonas aeruginosa

Pseudomonas aeruginosa is a bacterium that can cause a range of infections in humans. It

can be introduced to the water from bathers or from the surrounding environment.

Pseudomonas in the water can mean that disinfection systems are not operating as they

should, and appropriate remedial actions will need to be taken (refer to Appendix 6).

7.2.2 Chemical parameters

Chemical parameters that should be included in a verification monitoring program for

aquatic facilities include chloramines and ozone, if used. Guideline values for each of these

parameters are provided in Table A2.1 in Appendix 2.

7.2.3 Frequency of verification monitoring

Verification monitoring should never be used as a substitute for operational monitoring.

Higher risk facilities should undertake more frequent verification monitoring than lower risk

facilities. Table A2.4 in Appendix 2 provides guidance on risk categories for public aquatic

facilities. Table A2.6 provides recommended verification monitoring frequencies for

microbiological parameters for each risk category and Table A2.7 provides recommended

verification monitoring frequencies for chemical parameters for each risk category.

The frequency of verification monitoring may be reduced via a risk assessment process. For

example, where long-term monitoring (for example, monthly over a full calendar year of

operation) shows a chemical parameter to be consistently compliant with the guideline

level, frequency can be reduced to quarterly.

The frequency of verification monitoring may also have to be increased in some

circumstances. For example, following any significant change in pool operations or treatment,

during high use periods or following a change in chemical used, verification frequency for

relevant parameters should be increased until evidence of a return to stable values is shown.

Frequent verification monitoring should also be undertaken at all public aquatic facilities

when commissioning new water treatment equipment, or when there is some uncertainty

about the effectiveness of the water treatment processes in place.

7.2.4 Taking a verification sample

Verification samples should be taken from a location furthest from the water inlets where

bathers have not been present for the previous 60 seconds. When taking verification

samples always take the following steps:

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• remove the cap from the sample bottle

• Immerse the bottle, neck down in the water to a depth of about 300 mm. At this point the

container should be tilted to face horizontally away from the hand and then be moved

horizontally until the container is full

• Remove the sample container, replace the bottle lid and label before storing in an

appropriate container (such as an esky or cooler). Ensure samples are maintained in the

conditions and sample submission timeframes specified by the laboratory. Freezer bricks

can be used to ensure the samples stay cool during transport and kept within the correct

temperature range and the required holding period

• Verification samples should be submitted to a laboratory that the National Association of

Testing Authorities (NATA) has accredited to perform the requested analysis

• Samples must be analysed within 24 hours of collection.

7.2.4.1 Microbiological sampling

Microbiological samples should only be taken using a sample container provided by the

analytical laboratory. It is important that the analytical laboratory is aware that the sample

is to be taken from an aquatic facility with disinfected water and provide the appropriate

neutralising agent in the sample container. Neutralising agent in the sample bottles helps to

ensure that the results of microbiological sampling are representative of the water quality.

Samples should be maintained in the conditions and sample submission timeframes

specified by the laboratory. Samples must be analysed within 24 hours of collection.

7.3 Record keeping

All aquatic facilities should maintain a record of operational and verification monitoring

results for at least 12 months. Monitoring logs should be filled out when samples are

analysed and then retained on site. An example of a monitoring log template is provided

in Appendix 7.

Aquatic facilities should have arrangements in place to ensure that the laboratory

undertaking the analysis immediately reports the results to the person(s) responsible for

managing and maintaining water quality. Results should be reviewed on receipt for

compliance with the appropriate water quality criteria (refer to Appendix 2). Appropriate

corrective actions should be undertaken in instances where non-compliant results are

observed.

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Bather hygiene and aquatic facility design are important factors in keeping swimming pools

clean and to prevent disease-causing microorganisms and environmental contaminants

being introduced.

Key points

• Do not swim if you have diarrhoea and do not swim for 14 days after

symptoms have stopped.

• Shower and wash with soap, especially your bottom, before swimming.

• Wash your hands with soap after going to the toilet or changing a nappy.

• Change nappies in nappy change areas only.

• Avoid swallowing pool water.

Chapter 8: Healthy swimming

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8.1 Exclusion periods following illness

Bathers can introduce large numbers of disease-causing microorganisms into the water.

Disease-causing microorganisms come from the faeces of infected bathers. The period

during which disease-causing microorganisms are excreted varies from person to person

however, once pool water is contaminated with these microorganisms, disease can spread to

other people, even when only small amounts of water are swallowed.

In the case of an infection with Cryptosporidium, an infected person will excrete

Cryptosporidium during the illness and up to 14 days after symptoms have resolved (two

weeks after the diarrhoea has stopped). This is particularly concerning because sufferers, even

those who are no longer symptomatic and have showered, may introduce a small amount of

faecal matter into the water, causing contamination. Furthermore, Cryptosporidium is resistant

to the levels of chlorine or bromine typically used for pool disinfection. This means it can

survive in the water for long periods and potentially make others sick.

Signage should be displayed at every public access point advising bathers who have

recently had a diarrhoeal illness to not swim for 14 days after symptoms stop. The signage

should also advise parents to exclude their children for 14 days if their children have had a

diarrhoeal illness. Staff who use a public aquatic facility as part of their job should also

adhere to these exclusion periods, although these staff may still undertake tasks that

don’t involve being in the water.

Public aquatic facilities can encourage parents to prevent ill children from attending swim

lessons by promoting exclusion periods and providing ‘catch-up’ swim lessons for children

who have recently had a diarrhoeal illness. All facilities should offer learn-to-swim class

structure fees to allow refunds or ‘catch-up’ lessons if a child is sick with diarrhoea (and for

14 days after symptoms resolve) during the enrolment period.

8.2 Showering

Some people can become infected with disease-causing microorganisms without becoming

ill; these are known as ‘asymptomatic’ infections. Although these people might not become

ill, they will still have disease-causing microorganisms in their faeces. These people, like all

other bathers, may have small amounts of faecal material on their bottom, which can

transfer disease-causing microorganisms into the water. For this reason, it is important that

all bathers shower and wash with soap before entering the water.

Pre-swim showering is a difficult requirement to enforce for many existing aquatic

facilities. Bathers can be prompted to shower before using the facility via strategically

placed signage at public access points, by providing soap dispensers in the shower

facilities and ensuring change rooms are kept hygienic and pleasant to use. Visual and

verbal reminders to encourage bathers to shower before using a public aquatic facility can

help to change behaviour, reduce chlorine demand and reduce the rate at which

disinfection by-products are created.

In the design of new aquatic facilities, showers should be easily accessible and

strategically located. Consider designs that require bathers to enter the change rooms

before they can enter the aquatic facility itself because this will encourage bathers to

shower before entering the water.

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8.3 Toileting and handwashing

To help minimise public health risks, it is important to encourage proper toileting

behaviour among bathers. Parents and the guardians of children should be encouraged to

ensure their young children use the toilet before entering a public aquatic facility as well

as regularly while at the facility. Toilets should include signs to encourage bathers to wash

their hands with soap before returning to the water. Always provide enough soap for

handwashing. In the design of new aquatic facilities, toilets should be easily accessible

and positioned close to the swimming area(s).

8.4 Changing nappies

Nappy change areas should be provided in an easily-accessible location, kept clean,

sanitised regularly, and always be supplied with soap for handwashing. Wash-down water

from nappy change areas should not be allowed to flow to the pool or stormwater. Bins

should be provided for used disposable nappies and these should be emptied regularly.

Infant ‘aqua nappies’ and swim pants are commonly used but can give a false sense of

security regarding faecal contamination. There is no evidence to suggest that they can

prevent faecal material from leaking into the pool.

Regular nappy changing and frequent trips to the toilet can reduce the chance of a faecal

accident. Staff should let patrons know that nappies can only be changed in nappy change

areas rather than near the water’s edge.

8.5 Avoid swallowing pool water

Many illnesses associated with public aquatic facilities occur after swallowing contaminated

water, so all bathers should be discouraged from drinking pool water. Children should also be

supervised and discouraged from ‘whale spitting’ because this can often lead to accidently

swallowing water. If possible, locate drinking fountains at convenient locations within the

aquatic facility, particularly near areas used for exercise.

8.6 Assistance animals

Assistance animals (such as guide dogs) can be permitted to enter a public aquatic facility

but should not be permitted to enter the water.

Water quality guidelines for public aquatic facilities - December 2019 Page 39 of 70

8.7 Signage

Appropriate signage can help ensure bathers practise good hygiene. It is best to display

signage at each public access point that says:

• If you currently have, or have had, diarrhoea you should not enter the water. You should

not swim for 14 days after symptoms have stopped.

• Parents/guardians of children who have had diarrhoea in the past 14 days should ensure

their children do not enter the water.

• Please shower using soap and rinsing thoroughly before entering the water.

• Avoid swallowing the pool water.

• Parents/guardians should ensure young children use the toilet before entering the water

and regularly while at this facility.

• Do not change nappies beside the pool or rinse off your child in the pool. Use the change

room provided.

• Wash your hands thoroughly after using the toilet or changing nappies. Please use the

soap provided.

• Do not urinate in the pool. This contaminates the pool water.

• Faecal accidents can happen. If you or your child doesn’t quite make it to the toilet,

please tell our staff immediately. Confidentiality will be respected.

8.8 Minimising the likelihood of

environmental contamination

Environmental contamination can affect water quality in many ways. Public aquatic facilities

should be designed to reduce the likelihood of environmental contaminants being

introduced into the water.

For outdoor facilities, the surfaces around the facility should be sloped to direct stormwater

away from the water body. Nearby trees should have overhanging branches removed. Any

play equipment should be designed to discourage birds from roosting on it, and barriers

(fences) are recommended to exclude animals.

For indoor aquatic facilities, environmental contamination is also a concern and is

predominantly caused by bathers carrying microorganisms and organic matter into poolside

wet areas.

For a proactive approach to minimise environmental contamination, consider the following:

• Dirt traps – Matting should be placed at the entry and exit points to aquatic facilities to

capture dirt and additional environmental contaminants carried in on footwear.

• Shoe removal points – Appropriately signed areas for shoe removal, on entry to pool

change areas and poolside wet areas, can reduce contamination from the external

environment. Providing free storage lockers (with a key deposit) for patron’s shoes and

bags can also help to facilitate this change.

Water quality guidelines for public aquatic facilities - December 2019 Page 40 of 70

9.1 Response procedures

Despite the best efforts of public aquatic facility operators, the water in an aquatic facility

may become contaminated or a water treatment failure may occur. These incidents often

present a real risk to the health of bathers and it is therefore necessary for the operator(s)

to respond appropriately.

Operators should have documented and readily accessible procedures for responding to

incidents and be trained to carry out these procedures.

Appendix 6 provides guidance on responding to water quality incidents or treatment failures

that may affect public health. These incident response procedures are primarily for larger

Key points

• Incidents that adversely affect water quality can occur at any public aquatic facility.

• Operators should have documented procedures for responding to incidents.

• Staff should be trained to respond to incidents appropriately.

Chapter 9: Incident response

Water quality guidelines for public aquatic facilities - December 2019 Page 41 of 70

aquatic facilities with large volumes of water. For smaller aquatic facilities, it may be easier

to empty the affected water body, remove any accumulated contaminants retained in the

filter, refill and re-establish the necessary water balance and disinfectant residual.

9.2 CT value

In incident response, it is important that all public aquatic facility operators are familiar with

the concept of disinfection CT; a measure of disinfection effectiveness. CT is the concentration

of the disinfectant residual multiplied by the contact time at the point of residual

measurement. It is expressed as milligrams (mg) of chlorine per litre (L) times the number of

minutes for which this concentration of chlorine is maintained (e.g. 15 mg.min/L). CT values are

used to determine what concentration of disinfectant residual and what length of time is

required to inactivate a certain type of disease-causing microorganism. Variations in

disinfection time for a range of pathogenic organisms are shown in Table 2.

Table 2: Disinfection times for selected pathogens in pools

Contaminant

Disinfection time

(1 mg/L chlorine at pH 7.5 and 25°C)

E. coli bacteria < 1 minute

Hepatitis A virus 16 minutes

Giardia parasite 45 minutes

Cryptosporidium parasite 15,300 minutes (10.6 days)

Note that in practice only the Cryptosporidium value is relevant to most circumstances since that is the

most resistant pathogen.

Note that these disinfection times relate to the given pH, temperature and disinfectant concentration

ranges, and are influenced by other factors such as turbidity and cyanuric acid. For instance, required

contact times will increase as pH rises and decrease as temperature rises, and vice versa.

9.2.1 Contact time required to inactivate Cryptosporidium

A CT of 15,300 mg.min/L is required to inactivate Cryptosporidium. This can be achieved by

maintaining a free chlorine concentration of 20 mg/L for 13 hours (15,300 ÷ 20 = 765 minutes

or ~13 hours), or 10 mg/L for 26 hours (15,300 ÷ 10 = 1,530 minutes or ~26 hours), or via

alternative combinations of chlorine concentration and time that achieve the required CT. A

higher CT applies to water with cyanuric acid, as noted in Appendix 6. Elevated levels of

chlorine may damage the pool and its components. If required, consult a pool treatment

specialist to determine a suitable combination of concentration and time for the affected

pool(s). Hyperchlorination may not be required if a facility has a system that is validated to

treat Cryptosporidium risk (for example, UV disinfection) and can be proven to have been

operating within the validated parameters during and since the contamination event.

Water quality guidelines for public aquatic facilities - December 2019 Page 42 of 70

Operators of public aquatic facilities should be committed to training and continuous

professional development. Membership with a recognised industry body is strongly

encouraged.

The level of operator training should be proportionate to the risk of the facility. Operators of

high-risk aquatic facilities should undertake more extensive training than those who operate

lower risk facilities. It is strongly recommended that operators of high-risk facilities

complete the relevant competency of either a Certificate III (course code CPP31218) or

Certificate IV (course code CPP41312) in Swimming Pool and Spa Service, as offered by a

registered training organisation.

The minimum standard for aquatic facilities would be for staff to undertake a short course

offered by an industry body or registered training organisation. These typically cover the key

water quality-oriented competencies of the Certificate III or IV.

Facility managers should ensure they have adequately trained staff who understand the

treatment processes and know how to maintain water quality. Managers of public aquatic

facilities, particularly managers of larger facilities such as aquatic centres and water parks,

should also consider self-accrediting or obtaining formal accreditation under an industry-

led accreditation framework for facility managers. This may involve completing

qualifications specific to the role of managing a public aquatic facility and undertaking

continuous professional development.

Key points

• All staff involved in operating a public aquatic facility should undertake

appropriate training for their role.

• Staff who operate high-risk facilities should undertake more extensive training.

• Managers of larger public aquatic facilities should consider obtaining industry

accreditation.

Chapter 10: Operator training

Water quality guidelines for public aquatic facilities - December 2019 Page 43 of 70

Appendices

Appendix 1: Interactive water features

(splash pads, spray parks and water play areas)

The information provided below will help operators of IWFs to minimise the risk to public

health.

Risk management

Interactive water features are considered high risk facilities and it is therefore strongly

recommended that all IWFs have site-specific risk management plans.

Location

IWFs are often located within public open spaces such as parks, so it is important to consider

surrounding land uses and how other activities in the neighbouring area may affect the water

quality of an IWF. For example, sand pits, garden beds and trees will increase the volume of

physical contaminants (such as sand, dirt and leaf litter) entering the IWF. This will

compromise the effectiveness of filtration and disinfection systems.

General site sanitation, including the availability of public infrastructure (such as toilet

and shower facilities) will reduce physical and microbiological contamination of the IWF

water system. Access to showers, toilets and baby change facilities encourages good

hygiene practices among IWF users.

Ideally, fencing should be provided to keep out dogs and other animals during and outside

operating hours. If this cannot be achieved, where IWFs are located in areas where animals

may be present (for example, near dog parks), providing bag dispensers can prompt owners to

collect and dispose of animal faeces.

System design

Full system design plans (as installed) and operating manuals should be maintained so they

can be reviewed by an environmental health officer as required.

The following factors should be considered when designing an IWF:

• the quality and availability of the source water (ideally, only potable water should be

used)

• containment structures and drainage including upstream interceptor drains to prevent

stormwater runoff entering the IWF

• water circulation – recirculating water (subject to treatment and re-use) versus non-

recirculating water (passes through the IWF only once)

• infrastructure – appropriately sized to achieve effective water circulation, turnover,

filtration and disinfection targets

Water quality guidelines for public aquatic facilities - December 2019 Page 44 of 70

• materials and system components – fit for purpose (slip resistant, anti-entrapment) and

able to withstand ongoing exposure to the surrounding environment including varying

disinfection concentration levels (such as during periodic shock dosing)

• water flow – engineered to prevent both water stagnation and water pooling

• spray plume height and velocity – high spray plumes may expose more people due to the

drift of water particles, including people who may not be directly using the facility; low

spray plumes may be more appealing to young children, resulting in accidental or

intentional water consumption

• backflow prevention – this ensures water supply lines are protected from contamination.

Any backflow device should be installed and commissioned to comply with the relevant

plumbing and drainage legislation.

Recirculating systems

Water storage and circulation

Water should be stored and circulated to allow adequate water turnover and distribution of

disinfectant throughout all parts of the system. Water tanks should be accessible for

cleaning and inspection and be capable of complete draining. Storage capacity, including

both the size and number of tanks required, must be sufficient to ensure an adequate

residual level of disinfectant is maintained within the system.

Water temperature is an important consideration when sizing water storage tanks. Small

volumes of water will heat rapidly when exposed to external surfaces during IWF operation

increasing the risk of microbiological growth. A water turnover rate of no more than 20

minutes is recommended due to the relatively small volumes of water and high pollutant

load associated with IWFs. A flow gauge should be fitted to the system to demonstrate an

adequate flow rate within the IWF.

Treatment

Filtration: Filtration systems should be fitted to remove particulate matter (soils, leaves etc.)

and potential disease-causing microorganisms. The filtration system should run constantly

while the IWF is open to users.

New filtration systems should be designed to maximise the removal of Cryptosporidium.

Filters capable of removing particles 5 microns in diameter and achieving a filtrate turbidity

of no more than 0.5 NTU consistently will provide additional protection against

Cryptosporidium.

Disinfection: Automatic dosing equipment and online monitoring equipment should be

fitted to control the level of disinfectant in the water. Refer to Table A2.1 in Appendix 2 for

water quality parameters and targets. Using cyanuric acid is unlikely to be beneficial where

the majority of the water is contained in a balance tank. In addition, using cyanuric acid in

such instances may reduce the effectiveness of chlorine disinfection.

Secondary disinfection: Secondary disinfection is recommended, usually in the form of UV

disinfection, for all IWFs. UV disinfection can inactivate Cryptosporidium oocysts and medium

pressure UV lamps can control combined chlorine while improving the water quality (including

the odour from combined chlorine). A UV disinfection system should be installed in a location

Water quality guidelines for public aquatic facilities - December 2019 Page 45 of 70

prior to the chlorine dosing point and run constantly while the IWF is open to effectively

control the combined chlorine levels. Prioritise using validated equipment that is capable of

delivering a UV dose required to achieve a minimum 99.9% inactivation of Cryptosporidium

(Centers for Disease Control and Prevention, 2018).

On-site monitoring

Daily on-site monitoring is essential for all IWFs and should include physically inspecting the

site. This is important to maintain an understanding of water quality and to verify the

accuracy and reliability of any remote monitoring. The frequency of monitoring should be

determined as part of the site-specific risk management plan. Routine operational

monitoring should include free chlorine, total chlorine, pH, alkalinity, cyanuric acid (if used)

and water temperature. Refer to Table A2.1 in Appendix 2 for water quality parameter targets.

Records of physical inspection and on-site operational monitoring should be maintained

and made available for compliance inspection.

Remote monitoring

To enable real-time, remote monitoring of free chlorine levels, pH and water temperature,

IWF operators should install probes for free chlorine, pH and temperature.

The probes should be configured to allow automatic shutoff of the IWF when the free

chlorine levels, pH levels or water temperature are out of specification.

If remote monitoring is used, the results should be reliable and accessible during operating

hours and made available during compliance inspections.

Signage

Safety signage should be provided in a conspicuous location(s) and include:

• contact details for reporting issues/faults with the IWF

• advice to not swallow the water

• advice not to use the IWF if someone has diarrhoea, and for 14 days after symptoms have

stopped

• advice for babies and toddlers to wear tight-fitting swim nappies

• the location of the nearest public toilets/change rooms

• advice that animals are prohibited from accessing the IWF.

Assistance animals

Assistance animals (such as guide dogs) can be permitted to enter an area with an IWF but

should not be permitted to enter the IWF or drink the water.

Seasonal operation

For any IWF that are operated seasonally, to minimise water quality risks the IWF should be

drained to remove any stagnant water prior to closing for the season. Prior to re-opening,

the system should be cleaned and disinfected.

Water quality guidelines for public aquatic facilities - December 2019 Page 46 of 70

Operator skills and knowledge

The owner or operator of an IWF should take reasonable care to ensure the person(s)

responsible for managing the IWF has the appropriate skills, knowledge and experience.

Further information on operator training is provided in Chapter 10.

Non-recirculating systems

These systems present a lower public health risk and therefore may not require treatment as

they:

• use mains drinking water supply; and

• do not recirculate water.

Water quality guidelines for public aquatic facilities - December 2019 Page 47 of 70

Appendix 2: Water quality criteria and

monitoring frequencies

Table A2.1 Chemical criteria for facilities using chlorine-based primary disinfectants

Parameter

Situation

Criteria

Free chlorine

Any pool without cyanuric acid,

other than a spa pool

Min. 1.0 mg/L

Outdoor pool with cyanuric

acid

Min. 2.0 mg/L

Spa pool

Min. 3.0 mg/L

Interactive water feature

Min. 1.0 mg/L

Combined chlorine

(chloramines)

Any pool or interactive water

feature

Max. 1.0 mg/L, ideally < 0.2

mg/L

Total chlorine

Any pool or interactive water

feature

Max. 10 mg/L

Turbidity (pool water)

Any pool or interactive water

feature

Max. 1 NTU, ideally < 0.5 NTU

Any pool or interactive water

feature

7.2–7.8

Total alkalinity

Any pool or interactive water

feature

80–200 mg/L

Cyanuric acid

Outdoor pool only

Max. 50 mg/L, ideally ≤ 30 mg/L

Ozone

Any pool or interactive water

feature

Not detectable

mg/L is equivalent to parts per million or ppm

Free chlorine concentration should be increased when high bather numbers are anticipated to ensure

concentrations are never less than the minimum.

Residual excess ozone is to be quenched before circulated water is returned to the pool.

Water quality guidelines for public aquatic facilities - December 2019 Page 48 of 70

Table A2.2 Chemical criteria for facilities using bromine-based primary disinfectants

Parameter

Situation

Criteria

Bromine

Any pool, other than a spa

pool

Min. 2.0 mg/L

Spa pool

Min. 6.0 mg/L

Any pool

Max. 8.0 mg/L

Any pool

7.2–8.0

Sodium bromide

Bromine bank system

Max. 8.0 mg/L

Ozone

/bromide system

Max. 15 mg/L

Turbidity (pool water)

Any pool

Max. 1 NTU

, ideally <0.5 NTU

Total alkalinity

Any pool

80–200 mg/L

Cyanuric acid

Any pool

None – no benefit

Table A2.3 Microbiological criteria for all facilities

Parameter Guidelines value

Escherichia coli (or thermotolerant

coliforms)

Less than 1 CFU

/100 mL or

less than 1 MPN

/100 mL

Pseudomonas aeruginosa

Less than 1 CFU/100 mL or

less than 1 MPN/100 mL

Heterotrophic colony count (HCC) Less than 100 CFU/mL

mg/L is equivalent to parts per million or ppm

Bromine concentration should be increased when high bather numbers are anticipated to ensure

concentrations are never less than the minimum.

Ozone quenching is not required in an ozone/bromide system.

If turbidity is measured immediately post filtration, it should not exceed 0.5 NTU (DIN 19643 (2012-11)).

NTU - Nephelometric Turbidity Unit.

CFU - colony forming units

MPN - most probable number

Water quality guidelines for public aquatic facilities - December 2019 Page 49 of 70

Table A2.4 Risk categories to inform monitoring frequencies

Low risk facilities Medium risk facilities High risk facilities

• Retirement village pools

(not used for organised

exercise activities e.g.

private learn to swim

classes)

• Residential apartment

pools

• Diving pools

• 25 m and 50 m pools

• Hydrotherapy pools

• School pools

• Gym pools

• Resort pools

• Holiday park pools

• Motel pools

• Theme park wave pools

• Spas

• Interactive water

features

• Wading pools

• Learn-to-swim pools

• Program pools

• Water slides

• Shallow-depth

interactive play pools

• Pools used by

incontinent people

• Artificial lagoons with

unrestricted access

Adapted from: NSW Department of Health 2013 - Public swimming pool and spa pool advisory document

In instances where a facility manager is operating a type of facility that is not included in

Table A2.4, the manager should identify the type of facility that is most similar and monitor

accordingly.

If a facility falls into multiple risk categories, the facility should be monitored as if it were

the type of facility in the highest risk category. For example, if a gym pool is used for learn-

to-swim classes, the facility should be categorised as high-risk.

Water quality guidelines for public aquatic facilities - December 2019 Page 50 of 70

Table A2.5 Recommended minimum operational monitoring frequency

Parameter Low-risk facilities Medium-risk facilities High-risk facilities

Free chlorine and

combined

chlorine; or

bromine

For facilities with automated monitoring

1 daily sample

For facilities without automated monitoring

1 daily sample

3 daily samples

5 daily samples

Tested at the same time as for disinfectant residual (all facilities)

Water balance

(includes calcium

hardness, total

alkalinity TDS and

temperature)

Weekly (all facilities)

Turbidity

Daily (all facilities)

Cyanuric acid

(if used)

Weekly (all facilities)

When automated monitoring is in place, the daily sample refers to a sample that is taken by hand and is

analysed manually.

Water quality guidelines for public aquatic facilities - December 2019 Page 51 of 70

Table A2.6 Recommended microbiological verification monitoring frequency

Parameter Low-risk facilities Medium-risk

facilities

High-risk facilities

Escherichia coli

(or thermotolerant

coliforms)

Quarterly Quarterly Monthly

Pseudomonas

aeruginosa

Quarterly Quarterly Monthly

Heterotrophic

colony count

(HCC)

Quarterly Quarterly Monthly

Note that the frequency of monitoring should be increased if the bather numbers increase significantly. For example,

during school holidays when bather numbers at public facilities increase significantly, medium-risk aquatic facilities

should be monitored as if they were high-risk facilities.

Table A2.7 Recommended chemical verification monitoring frequency

Parameter Low-risk facilities Medium-risk facilities High-risk facilities

Chloramines

(combined

chlorine)

Quarterly Quarterly Monthly

Ozone (if used) Quarterly Quarterly Monthly

Note that the frequency of monitoring should be increased if the bather numbers increase significantly. For example,

during school holidays when bather numbers at public facilities increase significantly, medium-risk aquatic facilities

should be monitored as if they were high-risk facilities.

Water quality guidelines for public aquatic facilities - December 2019 Page 52 of 70

Appendix 3: Troubleshooting guide

The information in the following table should be used as a guide only.

Where available, the troubleshooting guide provided by the manufacturer of pool equipment

should be preferentially used. There may be other causes that are not listed. Misdiagnosis or

inappropriate action can worsen some problems to a point where the safety of bathers and

staff may be at risk. Only suitably qualified or experienced staff should diagnose or undertake

corrective actions. If you are unsure, it is best to get professional advice.

Table A3.1 Troubleshooting guide

Problem Possible reasons Action

pH too high

Mains water is alkaline

(and hard)

Add more acid

Alkaline disinfectant

used

Consider changing to less alkaline

disinfectant

Adjust regularly/frequently/automatically

by acid dosing

pH too low

Mains water is acidic

Add more alkali (for example, sodium

bicarbonate/ soda ash)

Acidic disinfectant used

Check pH probe and control settings

Adjust regularly/frequently/automatically

by alkali dosing

pH fluctuations

Water is not buffered –

alkalinity is too low

Check and raise alkalinity

Dosing erratic Check dosing accuracy and frequency

pH difficult to

change

Water too buffered –

alkalinity too high

Consider backwashing and topping up with

make-up water or reducing alkalinity by

adding acid

Water quality guidelines for public aquatic facilities - December 2019 Page 53 of 70

Problem Possible reasons Action

Cloudy,

dirty water

Bathing load too high Reduce bathing load

Filtration inadequate

Check filter, coagulant dosing, filtration

rate, backwash

Cloudy, clean

water

Hardness salts coming

out of solution

Check and where necessary correct pH,

alkalinity, hardness

Air introduced when

dosing coagulant

Check on coagulant dosing; check air

release on filters and for air leaks on the

suction side of the pump

Cloudy, coloured

water (outdoor

pools mainly)

Algae – sunlight, poor

hydraulics

Increase residual level and backwash;

consider using algicide as directed by the

label when the pool is not in use

Slimy, coloured

growth on pool

walls, floor, black

on grouting

Algae – sunlight, poor

hydraulics

Without bathers, brush or vacuum off

algae, increase disinfectant level,

backwash, consider using algicide

Water has bad

taste or smell –

irritates eyes and

throat

High combined chlorine

Check combined chlorine levels and type;

be prepared to dilute or correct free

chlorine level

pH wrong Check and correct if necessary

Chlorine level

difficult to

maintain

Sunlight Consider a stabiliser (cyanuric acid)

Chlorine product has

deteriorated and lost

strength

Check storage condition of chlorine, shelf

life, and test strength of chlorine

Bather pollution Reduce bathing load

Filter blocked, turnover

reduced, hydraulics poor

Check filter, strainer, flow rate and valves.

Consider air-scouring, where possible.

Injectors blocked Check chlorine injection point

Water quality guidelines for public aquatic facilities - December 2019 Page 54 of 70

Problem Possible reasons Action

Filter blocked

(pressure across

the filter is too

high)

Backwashing/ cleaning

too frequent – or scale

blocking the filter

Check and improve backwash

effectiveness; consider replacing filter

media

Incorrect coagulant

dosing

Check coagulant dosing; inspect filter

Water clarity

generally poor

Wrong filter or incorrect

use

Check filtration media (backwashing, etc.)

Insufficient chlorine Check and correct free chlorine residual

Incorrect or no coagulant Check coagulant use

Hard scale on

surfaces, fittings,

pipes, etc.; water

may feel harsh

Hardness salts coming

out of solution

Check and where necessary correct pH,

alkalinity, hardness

Cannot get test kit

readings for free

chlorine residual

Chlorine levels too high Test a 5:1 diluted water sample

Chlorine levels too low Check chlorine dosing

Poor air quality

(indoor pools)

Air circulation poor

Check air handling – introduce more fresh

air

Combined chlorine too

high

Restore recommended chlorine levels by

achieving breakpoint to oxidise

chloramines

Temperature too high Reduce to recommended levels

Water has a salty

taste

Dissolved solids too high Dilute with mains water

Staining at water

inlet

Irons salts coming out of

solution

Check pH, water balance, coagulation

Adapted from: Pool Water Treatment Advisory Group 2017

Water quality guidelines for public aquatic facilities - December 2019 Page 55 of 70

Appendix 4: Recommended turnover times

Ideally, aquatic facility turnover times should be calculated on a site-specific basis, as

turnover interacts with other key aspects of pool operational management including bather

numbers, pool volume, bather hygiene and pool circulation (including location and capacity

of inlets and outlets). Acceptable approaches to calculating site-specific turnover times can

be found in the NSW Department of Health 2013 - Public Swimming Pool and Spa Pool

Advisory Document (Chapter 7) and the UK Pool Water Treatment Advisory Group 2017 -

Swimming pool water – Treatment and quality standards for pools and spas (Chapter 6).

If a site-specific calculation is not used, the following table shows some recommended

turnover times.

Table A4.1 Recommended maximum turnover times for different types of public aquatic

facilities

Maximum

turnover

time

Pool type

20 min Interactive water features and spas

30 min Hydrotherapy pools

1 hour Waterslides, outdoor toddler wading, indoor learn to swim pools

2 hours

Outdoor learn-to-swim, lazy river, program and wave pools,

artificial lagoons with unrestricted access

4 hours

25 m and 50 m leisure and school pools (2 hours if used by

general public)

6 hours

Retirement village pools (not used for organised exercise

activities), residential apartment, gym, resort, holiday park and

motel pools

8 hours Diving pools

Adapted from: Pool Water Treatment Advisory Group 2017 - Swimming pool water – treatment and quality standards for

pools and spas and the Centers for Disease Control and Prevention 2018 - The Model Aquatic Health Code

Water quality guidelines for public aquatic facilities - December 2019 Page 56 of 70

Appendix 5: Langelier Saturation Index

The most common method for determining the balance of water in a public aquatic facility is

the Langelier Saturation Index (LSI).

The LSI should be between –0.5 and 0.5, with an ideal value of 0.

The LSI is calculated using the following equation:

LSI = pH + AF + CF + TF – 12.1

Where:

• pH is the measured pH of the pool water

• AF is a factor related to the total alkalinity of the water

• CF is a factor related to the calcium hardness of the water

• TF is a factor related to the water temperature

• 12.1 is an average correction factor for total dissolved solids (TDS).

The values for each of the factors above can be obtained from Table A5.1.

Table A5. 1 Table of values for Langelier Saturation Index calculation

Measured

value for

total alkalinity

(mg/L)

Value to use

for the AF

Measured value

for calcium

hardness

(mg/L)

Value to use

for the CF

Measured

value for

temperature

(°C)

Value to use

for the TF

5 0.7 5 0.3

Plunge pools are typically > 10°C

25 1.4 25 1

50 1.7 50 1.3 8 0.2

75 1.9 75 1.5 12 0.3

100 2.0 100 1.6 16 0.4

150 2.2 150 1.8 19 0.5

200 2.3 200 1.9 24 0.6

300 2.5 300 2.1 29 0.7

400 2.6 400 2.2 34 0.8

800 2.9 800 2.5 40 0.9

1,000 3.0 1,000 2.6

40°C is the maximum allowable

spa temperature

Bold text indicates ideal operational ranges. Where the LSI is negative, the water is corrosive and may damage pool

fixtures and fittings. Where the LSI is positive, scale can form and interfere with normal operation.

Water quality guidelines for public aquatic facilities - December 2019 Page 57 of 70

Example calculation

Consider a pool with a pH of 7.4, total alkalinity of 100 mg/L, calcium hardness of 250 mg/L,

at 29°C.

Reading from the table, the alkalinity factor is 2.0, the calcium hardness factor is 2.0, and the

temperature factor is 0.7.

LSI = pH + AF + CF + TF – 12.1

LSI = 7.4 + 2.0 + 2.0 + 0.7 – 12.1

LSI = 0

This pool water is ideally balanced.

If the calcium hardness of the same pool was 1,000 mg/L, then the calcium hardness factor

would increase to 2.6. In this case, the LSI would be +0.6 and scale is likely to form. If scale

forms on heater elements and filter components, the pool will not operate efficiently.

Corrections to the Langelier Saturation Index

The LSI described above is applicable to most aquatic facilities. However, there are

exceptions related to facilities with high TDS water and for operators of outdoor pools using

cyanuric acid. These exceptions are discussed in detail in the American National Standard

for Water Quality in Public Pools and Spas (American National Standards Institutes, 2019). If

the TDS of the water in an aquatic facility is greater than 1,500 mg/L, the factors in the

American Standard should be used. Where outdoor aquatic facilities use cyanuric acid to

stabilise chlorine, this will affect the alkalinity, and the correction factors stated in that

document should be applied.

Water quality guidelines for public aquatic facilities - December 2019 Page 58 of 70

Appendix 6: Incident response

Diarrhoeal incident – public aquatic facilities that use

chlorine without cyanuric acid

(Remedial steps for spas - see page 61)

Diarrhoeal incidents pose a particularly high risk to the health of bathers. Immediately

closing the affected water body(ies) and undertaking appropriate remediation is the only

way to prevent the spread of disease.

Recommended remedial steps

1. Immediately close the affected water body and any other connected water body(ies) within the

aquatic facility and ensure staff involved in the response have appropriate personal protective

equipment.

2. Remove as much of the faecal material as possible using a bucket, scoop or another container

that can be discarded or easily cleaned and disinfected. Dispose of the faecal material to the

sewer. Do not use aquatic vacuum cleaners for removing faecal material unless the vacuum waste

can be discharged directly to the sewer and the vacuum equipment can be adequately cleaned and

disinfected.

3. Adjust the pH to 7.5 or lower.

4. Hyperchlorinate the affected water body(ies) by dosing the water to achieve a free chlorine

contact time (CT) inactivation value of 15,300 mg.min/L (for example, free chlorine of 20 mg/L for 13

hours or 10 mg/L for 26 hours, or via alternative combinations of chlorine concentration and time

that achieve the required CT).

5. Ensure filtration and any secondary disinfection systems operate for the entire

decontamination process.

6. If the filtration system incorporates a coagulation step, ensure coagulant concentration is

correct to enhance the filtration process.

7. After the required CT has been achieved, reduce total chlorine to below 10 mg/L. Sodium

thiosulphate can be added to neutralise excess chlorine.

8. Backwash filter media or replace the filter element as appropriate. Precoat filter media should

be replaced.

9. Ensure the water is balanced.

10. Hygienically clean, disinfect or dispose of materials, tools, equipment or surfaces that have

come into contact with contaminated water.

11. Record the incident and remedial action taken.

12. Reopen the water body(ies).

Cryptosporidium and/or general suspected illness or possible outbreak

here a state or local government environmental health officer suspects or confirms a public

aquatic facility has been linked to illness, or an outbreak of illness (including Cryptosporidium), all

water bodies in the facility should be disinfected as per the recommended remedial steps above.

This requirement may not apply if a facility has a system that is validated to treat Cryptosporidium

risk and it can be demonstrated to have been operating within the validated parameters during

and since the contamination event. Note that Cryptosporidium has been singled out since it is the

most common reported source of illness or outbreak associated with aquatic facilities in Australia.

Water quality guidelines for public aquatic facilities - December 2019 Page 59 of 70

Diarrhoeal incident – public aquatic facilities that use

chlorine with cyanuric acid

(Remedial steps for spas - see page 61)

Diarrhoeal incidents pose a particularly high risk to the health of pool bathers. Immediately

closing the affected water body(ies) and undertaking appropriate remediation is the only

way to prevent the spread of disease. Chlorine stabiliser (cyanuric acid) significantly slows

the rate at which free chlorine inactivates or kills contaminants such as Cryptosporidium. It

is therefore necessary to achieve a much higher free chlorine contact time (CT) than is

necessary in water bodies that do not use cyanuric acid.

Recommended remedial steps

1. Immediately close the affected water body and any other connected water body(ies) in the

aquatic facility and ensure staff involved in the response have appropriate personal protective

equipment.

2. Remove as much of the faecal material as possible using a bucket, scoop or another

container that can be discarded or easily cleaned and disinfected. Dispose of the faecal

material to the sewer. Do not use aquatic vacuum cleaners for removing faecal material unless

the vacuum waste can be discharged directly to the sewer and the vacuum equipment can be

adequately cleaned and disinfected.

3. Adjust the pH to 7.5 or lower.

4. Ensure cyanuric acid concentration is 15 mg/L or less (this can be achieved by partially

draining and adding fresh water without chlorine stabiliser to the affected water body).

5. Once the cyanuric acid concentration is 15 mg/L or less, use unstabilised chlorine to

hyperchlorinate the affected water body(ies) by dosing the water to achieve a free chlorine CT

inactivation value of 31,500 mg.min/L (for example, free chlorine of 20 mg/L for 28 hours or via

alternative combinations of chlorine concentration and t

ime that achieve the required CT).

6. Ensure filtration and any secondary disinfection systems operate for the entire

decontamination process.

7. If the filtration system incorporates a coagulation step, ensure coagulant concentration is

correct to enhance the filtration process.

8. After the required CT has been achieved, reduce total chlorine to below 10 mg/L

. Sodium

thiosulphate can be added to neutralise excess chlorine.

9. Backwash filter media or replace the filter element as appropriate. Precoat filter media

should be replaced.

10. Ensure the water is balanced.

11. Hygienically clean, disinfect or dispose of materials, tools, equipment or surfaces that have

come into contact with contaminated water.

12. Record the incident and remedial action taken.

13. Reopen the water body(ies).