Some of the Chemical additives, may only be reduced by Distillation or Revese Osmosis

Chapter 8 Drinking water treatment chemicals Endorsed NHMRC–September 2005, NRMMC- September 2006. Main Page. NHMRC
Drinking Water Guidelines. NHMRC Publications

Chapter 8 Drinking water treatment chemicals
Endorsed NHMRC – September 2005, NRMMC - September 2006.
8.1 Introduction
The production of safe reticulated drinking water is vital for society. In recent decades, there have been numerous examples throughout the world of poor water quality impacting adversely on human health. Such episodes are rare in Australia, but the dire consequences of compromised disinfection and blooms of cyanobacteria serve to remind us of the need for drinking water treatment.
Addition of chemicals to make water safe for consumption is widely practiced by the water industry and has generally been accepted by the community. However, safeguards must be sufficient to ensure that any residual amount of these chemicals, byproducts of their reactivity or minor contaminants in their formulations do not pose an unacceptable health risk.
Treatment chemicals are added to drinking water mainly to reduce or eliminate the incidence of waterborne disease, for other public health measures, and to improve the aesthetic quality of the water. Any chemical used in, on, or near drinking water sources, or used during the treatment of drinking water should:
• be effective for the desired outcome
• not present a public health concern
• not result in the chemical, its by-products or any contaminants exceeding drinking water guideline values.This chapter provides guidance on chemicals used during the storage, treatment, and distribution of drinking water, quality assurance procedures, and the requirements for gaining approval for these chemicals.
8.2 Scope and limit of application of this chapter
Chemicals used near water for purposes other than direct improvement of water quality are not considered as drinking water treatment chemicals. Such chemicals include fertilisers and other agricultural chemicals used in properties adjacent to water storages, herbicides used to reduce vegetation along waterways, and pesticides used to control mosquitoes and other disease vectors in water storages. Use of these chemicals near raw water sources should be carefully considered, and the risks associated with their use should be minimised to ensure that water quality and public health are not jeopardised. Further information on these chemicals is given in Section 6.3.3 and in the Australian & NZ Guide for Fresh & Marine Water Quality (NWQMS 2000).
This chapter does not cover the specialised chemicals used in water treatment for non-potable uses (e.g. chemicals used in industrial boilers and air conditioning cooling towers), nor does it cover the impact on water quality of materials in direct contact with water. Information on these chemicals and impacts is given in Australian Standards AS3666.1:2002 — Air handling and water systems of buildings Microbial control – design, installation and commissioning; AS5667.7:1998 — Water quality – Guidance on sampling of water and steam in boiler plants; and AS4020:2002 — Testing of products for use in contact with drinking water respectively.
Information on occupational exposure to drinking water treatment chemicals resulting from their manufacture, transportation or use should be obtained from the manufacturer and Material Safety Data Sheets (MSDS), or from the appropriate State or Territory Occupational Health and Safety Authority (see Section 8.9).
Chapter 8 Drinking water treatment chemicals
8.3 Overview of chemical treatment processes
In the production of drinking water, a number of different chemicals may be added to the water. The types and quantities of chemicals can vary widely and will depend on a range of factors including raw water quality, treatment processes employed and treated water quality objectives. Chemical treatment processes are used to:
• control algae
• remove turbidity and colour
• remove microorganisms
• remove algal metabolites and synthetic pollutants
• reduce organic matter
• reduce the concentration of iron, manganese and other elements
• reduce pesticides and herbicides
• control taste and odour
• soften buffer or modify the pH
• disinfect
• control corrosion in distribution systems.
Chemical treatments may also be used for other public health measures, including: fluoridation (to prevent dental caries)
The following sections outline common processes employed in water treatment to achieve these objectives.
8.3.1 CONTROL OF ALGAE. Algicides are used to reduce toxic or odorous algal blooms in water reservoirs. The chemical commonly used in the management of algal growth is copper sulfate. Before an algicide is used, the possible effects on aquatic biota, the accumulation of copper in sediments, the potential impacts on downstream treatment processes and final treated water quality should be considered. The use of copper as an algicide is controlled in some States. Information on the use of these chemicals should be obtained from the appropriate State or Territory authority (see Section 8.9).
8.3.2 COAGULATION AND FLOCCULATION.The primary use of coagulant and flocculant chemicals is in the removal of suspended and colloidal solids such as clays. Coagulation is particularly important in the treatment of surface waters. Removal of the solids is achieved by aggregating fine suspended matter into larger flocs. Coagulant and flocculant chemicals will also remove some natural organic matter, colour and microorganisms (e.g. bacteria, viruses and algae). The size and strength of the floc can be controlled and modified, depending on the treatment process in use, and the floc can be removed by sedimentation and filtration.
8.3.3 ADSORPTION. Adsorption is primarily used to improve water quality through the accumulation of substances at the interface between two phases, such as a liquid and a solid, due to chemical and physicochemical interactions. The solid on which adsorption occurs is called the adsorbent. Activated carbon is an excellent adsorbent.
Adsorption is commonly used to remove organic contaminants such as herbicides, pesticides, algal toxins and metabolites; it is also used to remove compounds which may impact on the taste and odour of water.
8.3.4 SOFTENING.Softening is undertaken as part of water treatment to remove calcium and magnesium salts, particularly carbonates and bicarbonates, which cause water hardness. Hard water can cause scale build-up on water heating elements and can cause problems with the use of soaps and detergents. Softening very hard waters can also lead to high concentrations of sodium in water. While this may possibly give the water a salty taste, it is unlikely to present a health concern. Water that is too soft can be corrosive, which may occur when reverse osmosis is being used for water treatment, in which case it may be necessary to restore some hardness to prevent corrosion.
8.3.5 OXIDATION.Various oxidants may be added to water to oxidise problem compounds. For example, chlorine or potassium permanganate may be added to control iron and manganese. The oxidised forms of iron and manganese are readily removed by coagulation, flocculation and filtration. Oxidants may also be used to oxidise compounds which impact on the taste and odour of water, and organic contaminants such as pesticides. Ozone, and possibly hydrogen peroxide, may be added to oxidise organic compounds, and thus reduce the amount of coagulant required. Adding these chemicals also helps to reduce the length of long-chain organic molecules, which are then more effectively removed by granular activated carbon.
8.3.6 DISINFECTION. Disinfection of water is generally used either alone or as the final step in water treatment, after clarification or filtration. Disinfection is widely used to prevent the passage of bacteria, viruses and some protozoa into the distribution system. Typical chemicals used for disinfection of drinking water supplies are strong oxidants, such as chlorine (and its derivatives, chlorine dioxide and chloramine), ozone and hydrogen peroxide. The efficiency of disinfection depends greatly on the quality of the source or treated water, and can also be strongly affected by conditions such as chemical contact time, the pH and turbidity of the water, and organic content of the water. The aim of treatment processes used before disinfection should be to produce water with the lowest possible turbidity and organic content. Excessive particulate matter in the water can protect microorganisms from the action of disinfection chemicals. Also, excess organic matter and other oxidisable compounds in water can react with disinfection chemicals intended to inactivate microorganisms and can result in an increase in the formation of disinfection byproducts (see Section 6.3.2 for general information on disinfection byproducts, and the fact sheets in Section V for information on specific byproducts). Best practice operation of a conventional water treatment plant should be able to produce treated water with a turbidity of less than 0.1 nephelometric turbidity units (NTU).
8.3.7 ADJUSTMENT OF PH. Adjustment of pH is important in drinking water treatment processes such as coagulation (particularly for the removal of natural organic matter), corrosion control and softening. Control of pH is also important for effective disinfection and for minimising the formation of disinfection byproducts. The efficiency of certain disinfectants is strongly dependent on pH.
8.3.8 ADDITION OF BUFFERING CAPACITY. Soft waters can be subject to pH change as they travel through the distribution system. The rate of change depends on a number of factors including the water hardness, pipe materials used (e.g. cement lined pipe), the contact time, temperature. Increasing the buffering capacity of the water can help control the rate of change of pH through the distribution system.
8.3.9 CORROSION INHIBITION. The mechanisms of corrosion in a water distribution system are complex, and involve an interrelated combination of physical, chemical and biological processes. These depend greatly on the materials used within the distribution system and the chemical properties of the water, particularly its buffering capacity. Water corrosivity can be minimised by adjustment of pH and increasing calcium carbonate hardness (resulting in a positive Langelier index). Corrosion can also be reduced by maintaining disinfection residual throughout the distribution system.
Corrosion inhibition chemicals (such as sequestering agents) are used to reduce corrosion of pipes and household services. They also control the build-up of scale deposits from the dissolved mineral content of drinking water. This is achieved through the addition of chemicals that form a protective film on the surface of pipes. While corrosion inhibitors reduce corrosion, limit metal solubility or convert one form of corrosion to another (e.g. alleviating tuberculation and replacing it with more uniform corrosion), they do not totally prevent corrosion.
8.4 Public Health Measures
8.4.1. FLUORIDATION.Fluoridation of drinking water is not a water treatment process, but has been and continues to be effective in reducing the incidence of dental caries. It has many advantages over alternative methods for fluoridation, due to its cost effectiveness, consistency of exposure, equal distribution to all socioeconomic groups, and safety. In some areas, fluoride can occur naturally in drinking water. In areas where the drinking water supply is artificially fluoridated (at the instigation of the relevant State or Territory health authorities), the process is generally undertaken after clarification and chlorination of the water, because fluoride ions may adsorb onto the surface of suspended matter in the water and be subsequently removed through these processes. Fluoridation is generally achieved by adding either a slurry of sodium fluorosilicate, a solution of hydrofluorosilicic acid or (less commonly) a saturated solution of sodium fluoride, added as a metered dose for a given rate of water flow. Correction of pH may need to be carried out after fluoride addition. Use of fluoride is controlled by State and Territory legislation and regulations, and local regulations. Some of these are outlined in Table 8.1 (see also Section 8.9).
Table 8.1 State and Territory fluoride legislation and regulations
Australian Capital Territory Electricity and Water (amendment) Act (no 2) 1989. No 13 of 1989—Section 13 New South Wales
Fluoridation of Public Water Supplies Regulation 2002. NSW Fluoridation of Public Water Supplies Act 1957
Northern Territory Dental Act Schedule 3 1999 NT
Queensland
Fluoridation of Public Water Supplies Regulation 1998. Reprinted as in force on 4 January 1999
Fluoridation of Public Water Supplies Act 1963. Reprinted as in force on 21 December 1998
South Australia
There is no fluoride legislation in South Australia
Tasmania
Fluoridation Act 1968
Victoria
Health (Fluoridation) Act 1973
Western Australia
Fluoridation of Public Water Supplies Act 1966
8.5 Assessment of chemicals acceptable for use in drinking water treatment
8.5.1 CHEMICALS PREVIOUSLY ASSESSED. The NHMRC has examined a wide range of chemicals for treating water in Australia. To be acceptable, the chemical must have a practical application (e.g. clarify dirty water, or destroy or inactivate harmful microorganisms). The chemical must achieve its purpose and must not be toxic when ingested at concentrations present in treated water.
A drinking water treatment chemical is considered suitable for use when used in accordance with standard operating procedures. This does not relieve a water authority from having risk control measures in place to ensure the effectiveness of a particular chemical in a water treatment process. For example controls need to be in place to prevent over- or under-dosing. Water treatment systems also need to be designed to ensure that residuals and contaminants from multiple treatment chemicals added will not exceed recommended guideline values at the consumer’s tap.
The potential for a chemical to interact with any other added chemical or other compounds present in the water also needs to be considered.
The chemicals listed in Table 8.2 are considered by the NHMRC to be suitable for use in the treatment of drinking water.
If a chemical not listed in this chapter is to be used in the treatment of drinking water, it is the responsibility of the water authority to seek advice from the appropriate state/territory health regulatory agency, and take into consideration health, environmental, and occupational health and safety issues.
The fact sheets in Section V provide detailed information on chemicals used in the treatment of drinking water.
Table 8.2 Chemicals recommended for use in the treatment of drinking water

8–6 Australian Drinking Water Guidelines
Table 8.2 Chemicals recommended for use in the treatment of drinking water (continued)
Treatment chemical Formula Original date of approval by NHMRC Uses

8.5.2 ASSESSMENT OF NEW WATER TREATMENT CHEMICALS
The procedure to gain approval by NHMRC for new drinking water treatment chemicals for use in Australia is undertaken on a case-by-case basis. Sponsors of a new water treatment chemical seeking inclusion of the chemical into the NHMRC Australian Drinking Water Guidelines should, in the first instance, contact the NHMRC. A comprehensive assessment of toxicological information will be required as part of the approval process.
National procedures established by the National Industrial Chemicals Notification NICNAS and Assessment Scheme (NICNAS)1 are followed when assessing existing chemicals, assessing a new use for an existing chemical or assessing new drinking water treatment chemicals for use in Australia. NICNAS reviews of toxicological data, undertaken through a cost-recovery arrangement with the sponsor of the chemical, are required prior to final consideration by the NHMRC.
The Australian Pesticides and Veterinary Medicines Authority APVMA (APVMA) are responsible for safety and efficacy assessment and registration of pesticides and veterinary medicines (including algicides).
8.6 Quality assurance for drinking water treatment chemicals
8.6.1 RISKS ASSOCIATED WITH DRINKING WATER CHEMICALS
A cornerstone of the management of drinking water quality (see chapters 2 and 3) is the analysis of hazards and the management of risk. The intentional addition of chemicals to water intended for drinking purposes carries with it a potential risk. This may result from any of the following:
• the toxicological properties of the chemical itself
• under dosing or overdosing of the chemical
• contaminants in the chemical arising from the manufacturing process or the raw materials used
• contaminants in the chemical arising during transport, storage and use on site
• by-products formed through the use of the chemical.
Contamination of chemicals can be minimised by the use of good manufacturing practice, which uses quality control and quality assurance programs to maximise product purity. The purity of chemicals used in Australia for the treatment of drinking water supplies will vary depending on the manufacturing process. Contaminants that may occur in specific treatment chemicals are outlined in the fact sheets (see Section V). The information in the fact sheets is based on the best available data at the time of publication. However, research and industry experience may lead to changes in manufacturing processes or better understanding of the properties of the chemicals, which in turn may lead to changes in procedures for how water treatment chemicals should be handled, stored and used.
8.6.2 MANAGING RISKS. A complete water quality management program needs to recognise any potential risks from use of drinking water treatment chemicals and include strategies to manage them appropriately. These risks should be minimised by the implementation of a quality assurance system for the management of production, supply, delivery and use of water treatment chemicals.
The first step in managing the risk associated with the use of drinking water treatment chemicals is
to ensure that the chemicals supplied meet a minimum standard, as established by the relevant State or Territory regulatory agency. For example, water authorities may formally specify the strength of active ingredient and acceptable contaminant levels in each drinking water treatment chemical (see Section 8.6.3). However, this in itself will not adequately control the risk. The contractual requirement should be supported by batch-testing data provided by the supplier from an independent NATA (National Association of Testing Authorities) accredited laboratory, and random testing carried out by the water authority itself. Chemicals should not be accepted for delivery unless a batch analysis certificate has been obtained and checked by the water authority.
Formal accreditation of the manufacturing facility by an independent accreditation agency (e.g. the International Organization for Standardization ISOor NSF International NSF provides a further level of risk management. Such accreditation should include random site visits to the manufacturing facilities by the relevant regulatory agency and, if warranted, the water authority.
Chemical suppliers should be evaluated and selected on their ability to supply products in accordance with required specifications. Documented procedures for the control of chemicals, including purchasing, verification, handling, storage and maintenance should be established to assure the quality of the chemical at the point of application (see Section 3.10.1). Responsibilities for testing and quality assurance of chemicals (supplier, purchaser or both) should be clearly defined in purchase contracts.
An important step in a quality assurance system for chemical addition to drinking water is to ensure that the required chemical is of the specified quality, and specified strength, and is delivered into the correct storage vessel, at the correct site at the correct time. This is necessary to:
• ensure that the correct chemical at the required concentration is used in drinking water treatment
• ensure that cross contamination of storages does not occur
• ensure inappropriate and unsafe mixing of chemicals does not occur
• help to ensure the health and well being of staff and contractors during the delivery and dosing process.
Broadly, the objective of the water treatment chemical quality assurance system is to manage all the factors associated with the specification, contract management, supply, storage, use and handling of water treatment chemicals that could adversely impact upon the health and wellbeing of staff, contractors and consumers. Box 8.1 outlines the components that make up an effective quality assurance system for drinking water treatment chemicals. http://www.nicnas.gov.au/

Chapter 8 Drinking water treatment chemicals
Box 8.1 Desirable components of a quality assurance system
The desirable components of a quality assurance system for chemicals used in the production of drinking water may include:
• Selection of chemical suppliers based on capability to meet specified requirements for supply and delivery, monitoring and analytical testing of contaminants.
• Selection of suppliers with a quality management system that is certified by an independent accreditation agency. An appropriate monitoring program to ensure compliance of chemicals with specifications. An audit process for the supplier’s manufacturing, storage and delivery processes. A formal checklist for the dispatch and delivery process.
• A delivery driver induction system for each site, with each driver inducted onto each site and appropriate record keeping procedures.
• The provision of details of the delivery site (site photographs may be useful).
• An identity check directly linking the delivery driver to the chemical company.
• The clear identification and labelling of chemical storage vessels, filling points and delivery pipe work at all sites (locks on filling points are desirable).
• A requirement that chemicals should only be delivered when an appropriate water authority staff member is present to check documentation including batch analysis certification and ensure unloading to the correct storage vessel.
• A standard operating procedure for the delivery and receipt of chemicals at each delivery site including a documented acceptance criteria system to assist site operations staff in assessing whether to accept or reject the delivery of a chemical.
• A gross visual check of the chemical and, where appropriate, simple physical testing by the water authority representative at the delivery site before unloading.
• A check by both parties that the delivery vessel is being connected to the correct storage vessel.
• A check that appropriate personal protective equipment is being worn, and that relevant health and safety requirements are being addressed.
• Appropriate recording and storage of relevant documentation.
• A system to ensure that any spillage associated with the delivery process is contained and does not escape to the environment. An emergency procedure in the event of possible systems failure or human error.

Association of Testing Authorities) accredited laboratory, and random testing carried out by the water authority itself. Chemicals should not be accepted for delivery unless a batch analysis certificate has been obtained and checked by the water authority.
Formal accreditation of the manufacturing facility by an independent accreditation agency (e.g. the International Organization for Standardization (ISO) or NSF International) provides a further level of risk management. Such accreditation should include random site visits to the manufacturing facilities by the relevant regulatory agency and, if warranted, the water authority.
Chemical suppliers should be evaluated and selected on their ability to supply products in accordance with required specifications. Documented procedures for the control of chemicals, including purchasing, verification, handling, storage and maintenance should be established to assure the quality of the chemical at the point of application (see Section 3.10.1). Responsibilities for testing and quality assurance of chemicals (supplier, purchaser or both) should be clearly defined in purchase contracts.
An important step in a quality assurance system for chemical addition to drinking water is to ensure that the required chemical is of the specified quality, and specified strength, and is delivered into the correct storage vessel, at the correct site at the correct time. This is necessary to:
ensure that the correct chemical at the required concentration is used in drinking water treatment
ensure that cross contamination of storages does not occur
ensure inappropriate and unsafe mixing of chemicals does not occur
help to ensure the health and well being of staff and contractors during the delivery and dosing process.
Broadly, the objective of the water treatment chemical quality assurance system is to manage all the factors associated with the specification, contract management, supply, storage, use and handling of water treatment chemicals that could adversely impact upon the health and wellbeing of staff, contractors and consumers. Box 8.1 outlines the components that make up an effective quality assurance system for drinking water treatment chemicals.

8–8 Australian Drinking Water Guidelines
Australian Drinking Water Guidelines 8–9
The combination of a chemical quality assurance system and a delivery and storage quality assurance system such as those outlined in Box 8.1 can significantly reduce risks to all stakeholders. The combined system should include formal quality audits (see Section 3.11).
8.6.3 SPECIFICATIONS FOR THE SUPPLY OF DRINKING WATER TREATMENT CHEMICALS
The preparation of specifications for a chemical supply contract can be a time consuming and difficult task. Documents should be prepared in conjunction with a risk assessment and controls recommended in Sections 8.5.1 and 8.5.2.
To simplify the process for water authority staff preparing their own specifications, an example specification for the supply and delivery of liquid aluminium sulfate (Al2SO4) to a water authority is provided in Box 8.2.
The specification includes details on the required content of aluminium which is often, but not always, expressed as equivalent aluminium oxide (Al2O3), product clarity, solids content and pH as well as specific impurity limits. The specification also details some delivery and acceptance criteria. Product strengths and basic characteristics of the chemicals can be obtained from the Drinking Water Chemical Fact Sheets in Section V. The water authority may customise these specifications to suit their particular situations and risks.
The Specification should also clearly define the arrangements and responsibilities for ensuring the treatment chemical is not contaminated during transport or storage prior to transport.

8.9 Useful contacts
AUSTRALIAN GOVERNMENT

National Health and Medical Research Council
GPO Box 9848 CANBERRA ACT 2601
Tel: (02) 6289 9191
E-mail: Info Internet: NHMRC

Australian Safety and Compensation Council (ASCC)
GPO Box 9879 Canberra ACT 2601
Tel: (02) 6121 6000
E-mail: info Internet: ASCC

National Industrial Chemicals Notification and Assessment Scheme (NICNAS)
GPO Box 58 Sydney NSW 2001
Tel: (02) 8577 8800
E-mail: Info Internet: NICNAS

AUSTRALIAN CAPITAL TERRITORY

Office of Chemical Safety Therapeutic Goods Administration
PO Box 100 Woden ACT 2606
Tel: 1800 020 653 (freecall) or (02) 6232 8444
E-mail: Info Internet: TGA

Health Protection Services ACT Health
Locked Bag 5 Weston Creek ACT 2611
Tel: (02) 6205 1700
E-mail: Info Internet: Health ACT

Environment ACT
PO Box 144 Lyneham ACT 2602
Tel: (02) 6207 9777
E-mail: Info Internet: Environment ACT

ACT Workcover
PO Box 224 CIVIC SQUARE ACT 2608
Tel: (02) 6205 0200
E-mail: Info Internet: ACT Workcover

NEW SOUTH WALES
Water Unit NSW Department of Health
Locked Mail Bag 961 NORTH SYDNEY NSW 2059
Tel: (02) 9816 0589
E-mail: Info Internet: Health NSW

Department of Environment and Conservation
PO Box A290 Sydney South NSW 1232
Tel: (02) 9995 5000
Email: info Internet: Department of Environment and Conservation

Workcover NSW
Locked Bag 2906, LISAROW NSW 2252
Tel: 02 4321 5000
Email:
Internet: Workcover NSW

NORTHERN TERRITORY
Department of Health and Community Services
PO Box 40596 CASUARINA NT 0811
Tel: (08) 8999 2400
Email: Info Internet: Department of Health and Community Services

Department of NT Department of Infrastructure, Planning and Environment
GPO Box 1680 DARWIN NT 0801
Tel: (08) 8999 5511
Internet: Department of Infrastructure

NT Worksafe
GPO Box 4821 DARWIN NT 0801
Tel: (08) 8999 5010
E-mail:Info Internet: NT Worksafe

QUEENSLAND
Environmental Health Unit Queensland Health
GPO Box 48 BRISBANE QLD 4001
Tel: (07) 3234 0938
E-mail: Info Internet: Environmental Health Unit Queensland Health

Environmental Protection Agency
PO Box 15155 CITY EAST QLD 4002
Tel: (07) 3227 8185 - EPA Hotline: 1300 230 372
Email: Info Internet: Environmental Protection Agency

Workplace Health and Safety Department of Industrial Relations
GPO Box 69 BRISBANE QLD 4001
Tel: (07) 3225 2000 WHS Hotline: 1300 369 915
Internet: Workplace Health and Safety Department of Industrial Relations

SOUTH AUSTRALIA
Environmental Health Service Department of Health
PO Box 6 Rundle Mall ADELAIDE SA 5000
Tel: (08) 8226 7100
E-mail: Info Internet: SA Environmental Health

Environment Protection Authority (SA)
GPO Box 2607 ADELAIDE SA 5000
Tel: (08) 8204 2000
E-mail: Info Internet: Environment Protection Authority (SA)

WorkCover Corporation
GPO Box 2668 ADELAIDE SA 5001
Tel: 13 18 55
E-mail: Info Internet: WorkCover Corporation

TASMANIA
Public and Environmental Health Department of Health and Human Services
GPO Box 125 Hobart TAS 7001
Tel: (03) 6222 7737
E-mail: Info Internet: Public and Environmental Health

Department of Primary Industries, Water and Environment
GPO Box 44 HOBART TAS 7001
Tel: 03 6233 2758 or 1300 368 550
E-mail: Info Internet: Department of Primary Industries, Water and Environment