ICEH Resources Information Sheet

WATER SUPPLY

Introduction

The objective of water supply is to provide adequate water that is suitable and safe for a variety of uses in the community. Water supply may be a complex system in a larger town or city or a simple rainwater tank attached to a house on a remote property. In terms of public health the common need for satisfactory water supply includes a source of water that is:

•  adequate to meet the demands for drinking water and personal and domestic hygiene needs
•  of a good quality that will not impact health.

The design, development and management aspects of water supplies are large subject areas. Many aspects of engineering and public health protection are involved. The following is an introduction to core concepts and factors related to water safety and quality in terms of public health protection.

Healthy water - healthy people

Water is one of the few things that we cannot live without. Adequate and safe drinking water is essential for achieving and maintaining good health. Worldwide experience shows that protecting and maintaining the water supply source and distribution systems will reduce the chance of a range of diseases for the users of water.

Water is used for many non-drinking uses in our homes and communities. It can be critical in keeping our living environment cool – through evaporative cooling, and it can be used for dust control. Many homes and communities use water to grow shade trees and provide landscaping around their homes or to grow crops that may otherwise be difficult to obtain. Consumption of poor quality drinking water is not the only way water may affect health. Diseases may also be contracted whilst preparing food or bathing using contaminated or poor quality water. Our health and the health of our community, particularly in dry environments where water may be limited, is closely related to access to adequate and safe water.

Australia is one of the driest countries in the world. As a result many remote communities have significant challenges in acquiring and providing adequate and safe water supplies. Communities in high rainfall areas may not have challenges in providing an adequate supply (in terms of quantity) but they may have challenges in providing safe water. This is because many other factors affect the safety of a supply including the types of land use in the catchment; access and maintenance of infrastructure; and access to finances for capturing, storing, treating (including disinfection where necessary) and distributing water to users.

Indigenous significance

All communities need to be active to ensure adequate and safe water supply. Many Indigenous communities, especially those in remote localities, face additional challenges in maintaining adequate and safe water supply. Factors affecting this include access to personnel and physical resources needed to maintain and manage a water supply. In many parts of Australia, meeting total demand for a range of uses can be an issue. Innovative approaches include integrated water management, that is, the use of clean fresh water for drinking and bathing plus reuse and/ or recycling of waste-water for secondary purposes such as landscape watering or dust control. These may be an option for maximising the benefit of what water is available.

Water sources vary significantly across Australia and corresponding to this, quality varies as well. Current sources of supply to Indigenous communities have been identified by ATSIC (2002) as:

•  bore water (62%)
•  town supply (15%)
•  rain water tank (9%)
•  river or reservoir (7%)
•  well or spring (5%)
•  other (2%).

Water is one component of the critical health-hardware that has been shown to be so important to improving functioning of housing in many communities across Australia. Adequate and safe water supply integrates with health-hardware and through this the work of Environmental Health Workers and Officers with their communities.

Sources of supply

There are many uses for water in our community. Not all of them require high quality water as is required for drinking water supplies. In most cases, drinking water is but one of the uses required of a water supply. Unless it is economic to develop a dual water supply, that is two supply lines with one being for raw water and the other for drinking water, a supply will need to be designed to treat and distribute all water to a drinking water standard. Determining intended uses and the needs for consumers in your community is important when deciding on the type of supply system to be used. Typical amounts of water used per house for health related uses in a remote arid community have been described by Pholeros (1997) as in the following table.

Possible sources of water for a community will be dependent on regional characteristics. In most cases only one of these types of sources will be available or cost effective for a community. If available, use of two or more sources could assist a community meet its total water demand.

Surface Water (Lakes, rivers)
If in largely undeveloped catchments, that is there is little or no urban, industrial or agricultural development, lakes and rivers can generally provide high-quality water. A weir is often used in rivers to increase available volume for supply. If used for drinking water supply, disinfection will be required.

Local Rainwater Storage (Rainwater tanks)
On-site water storage in small tanks supplied by diversion of downpipes from a roof or roofs functions as the catchment and collection system for a rainwater tank. Water can be of good quality but also can be affected in terms of quantity and quality by climatic seasonal factors and vegetation surrounding the site. Maintenance of roofs and gutters is important to ensure quality and efficiency in collection and to prevent a breeding ground for mosquitoes which can cause public health issues. Disinfection is important if used for drinking water supplies. Rainwater tanks are increasingly used in providing additional capacity alongside town supplies; for example, being used for non-drinking purposes including flushing toilets, yard cleaning and watering gardens.

Groundwater supplies (Bore-water, wells, springs)
Aquifers act as underground reservoirs for water that may have fallen as rain and then submerged many hundreds or thousands of kilometres away. These supplies are very important in arid areas and they need to be managed well, as overuse can quickly reduce the capacity for sustaining water quality and quantity of supply. Bore water is the most common source for supply in remote communities and generally water quality is adequate for use as drinking water with some treatment and disinfection.

Elements in a water supply

Common to all systems, whether large community supplies or single site supplies, are the following elements:

• a storage to hold water and to meet the fluctuating demands of users of the system. Typically this may be a weir or dam or a constructed reservoir or it may be an in-ground or above-ground tank in the instance of a small community or settlement. A rainwater tank fulfils this function when used for a single house.
• a treatment facility where water may be physically and or chemically treated to improve water characteristics and to make it suitable and safe for use. At its most basic, treatment should include disinfection to reduce risk from micro-organisms that may otherwise cause disease. A storage tank for treated water is usually required as part of the treatment facility.
• a distribution system to transport treated and or disinfected water from the source and or storage to the user. Typically this will be a network of pipes suitable to delivery of drinking water to users but it may include water-carting trucks.

Water quality and safety

The aim of any water supply is for it to be safe for users; that is, it should be of good quality with no contamination with any physical matter, chemical or organism capable of causing disease.

Good quality water is generally considered to be water free from contamination from the following:

Biological contaminants: Physical contaminants: Organic contaminants: Inorganic contaminants:	water borne diseases, pathogens and harmful organisms solids, dissolved solids, odour, hardness, turbidity pesticides, herbicides and weedicides salts, heavy metals, radioactive material

Typical sources of pollution
Drinking water sources or recreational water are most likely to be contaminated with human, animal, agricultural and industrial wastes. The hazards associated with human and animal wastes are mainly microbiological while those associated with industrial wastes are generally chemical. Agricultural wastes can be microbiological (of animal origin) or chemical (fertilisers, pesticides).

In addition pollution can provide the right nutrients and/or conditions for increased growth of naturally occurring organisms that may affect water supply treatment or quality. Blue-green algae (cyanobacteria) blooms and Naegleria fowleri (amoeba) are examples common to a number of localities in Australia. These naturally occurring organisms have particular and significant health effects and though naturally occurring, can be exacerbated by pollution from human or animal wastes. Each of these also has major implications in regard to suitability and management of water supplies if they are present in the locality.

Further information on Blue Green Algae can be found at the following:
Blue-Green Algae Information Sheet (PDF file 4pg) - Queensland Dept Natural Resources & Mines
Blue-Green Algae: A Guide (PDF file 4pg) - CRC for Water Quality & Treatment
BGA Information - Australian Academy of Science

Information on Naegleria fowleri can be found at the following:
Amoebic Meningitis (PDF file 6pg) - Western Australia Department of Health
Amoebic Meningitis - The Meningitis Centre

Water quality guidelines
The Australian Drinking Water Guidelines (ADWG) produced by the National Health and Medical Research Council has been adopted by most jurisdictions across Australia. The ADWG provides a series of guidelines (PDF file 209 KB) and fact-sheets on acceptable health and/ or aesthetic criteria for drinking water in terms of physical, chemical, radiological and microbiological parameters. The ADWG also provide a framework for how drinking water supplies should be maintained to ensure water remains safe for consumption.

If water is supplied to users to meet the ADWG for drinking water, the water will also be suitable in terms of public health for other household uses including bathing and cooking. Water meeting the ADWG will also be generally suitable for other community uses. However if a particular need has to be met as part of a community supply e.g. special irrigation purposes, then other guidelines may need to be met. Contact should be made within the relevant environmental protection agency in your State or Territory.

Water supply protection and management principles

The multiple barrier approach is recognised as the best-practice method for reducing contamination and health risks associated with water supply.

The provision of barriers to the transmission of pathogens and contaminants is important in reducing health risks associated with water. The multiple barrier approach is promoted in the ADWG and relies on using more than one type of protection or treatment and undertaking numerous actions from the water catchment through to a user’s tap. Examples include the following:

• Protection of source water from contamination with active catchment protection programmes
• Long detention times (weeks or months if possible) within off-line storages e.g. tanks/ reservoirs
• Water treatment e.g. coagulation, settling, and filtrations
• Disinfection of treated water
• Maintenance of residual chlorine throughout the distribution system.

Monitoring the microbiological status of water supply should be regarded as a check that the barriers are working.

The multiple barrier approach applies to all types of water supply, from small to large. The scope of the activities at different scales of systems will, however, need to increase in complexity as the scale of a system increases. An example of how this would work is shown in the following table.

Sanitary surveys
Sanitary surveys are an important tool for Environmental Health Workers when planning and making assessments of water supplies.

A sanitary survey involves inspections to check for any direct or potential sources of contamination of a water supply. They are particularly important where treatment of the water source is minimal or when there are concerns with water quality raised by the community or if there has been illness in the community that was likely to have been water-borne.

WHO (1996). Fact Sheets on Environmental Sanitation. WHO/EOS/96.4 World Health Organisation. Geneva

The frequency of sanitary inspections of a catchment will depend on the characteristics of the locality, the type of source of raw water (e.g. river, rainwater or bore), the time the water remains in storage (the longer the better as this would allow natural die-off of pathogens to occur), and the subsequent treatment that is provided. As well as regular inspections in the immediate vicinity of the off-take site, every catchment where habitation or public access exists should be thoroughly inspected at least once a year for potential sources of pollution.

Resources to assist EHWs design their own sanitary inspection are provided in the Tools section at the end of this document.

Disinfection of water

Disinfecting drinking water is of paramount importance to protect public health. Without disinfection an unacceptable risk would exist from exposure to harmful organisms that could cause widespread illness in the community.

Chlorination using chlorine gas or hypochlorite is the most common method of disinfection used worldwide. Effective chlorination is achieved by adding chlorine at an amount that ensures some remains as ‘free’ chlorine. The level at which free 'chlorine residual is held within any water supply will vary depending upon location-specific factors, but in major Australian water supplies typical ranges are held at between 0.1 mg/L to 4 mg/L. A recognised target value for reticulated supplies is 0.5mg/L of residual chlorine throughout the system.

Water may also be disinfected by physical (boiling) or other chemical (ozone, iodine) means. By far the most popular disinfection however is chlorination. Chlorination is popular as it is relatively easy and safe (with some worker safety protections) to use and dose into supplies and because the ability to provide a residual amount of chlorine in the water after its addition (dosing) provides an ongoing level of protection that other types of disinfectants can not.

The residual disinfectant is important as it can minimise bacterial re-growth and the effects of recontamination that may occur during distribution of water to the user from the storage or treatment plant.

Source: Technical Cards on Environmental Sanitation (WHO, 1997)

Disinfection with chlorine is most efficient in clean water. Highly turbid or muddy water will be hard to disinfect using chlorine. For this reason chlorine is best added after primary treatment or at least after settling and basic filtration.

Maintaining disinfection is an important tool for protection of public health. Chlorinating (disinfecting) a water supply is a relatively simple and cheap method for reducing risk of exposure to pathogens in the community. The Tools section below provides a series of extracts about low-technology methods for disinfection. These are sourced from the World Health Organization. Environmental Health Workers and community people can easily employ these methods in managing water supply hardware, e.g. community supply storages and rainwater tanks.

Rainwater Tanks

The enHealth monograph Guidance on the use of rainwater tanks (PDF 29pg) provides comprehensive information on rainwater tank uses, including the following:

• Water quality
• Construction
• Sizing of tanks
• Installation, maintenance and repairs
• Disinfection and mosquito control
• Use of supplementary water (from bores dams, rivers, creeks etc) with rainwater tanks

Tools for Working on Public Health and Water Supply

1. WHO (1997). Technical cards on environmental sanitation. (PDF file 46pg) World Health Organisation.
   - Collecting water samples - (PDF file 130 KB) methods - methods for taking samples to test for chlorine
   - Testing for chlorine (PDF file 82 KB) includes methods to determine chlorine levels and amounts required for effective disinfection
   - Disinfection of storage tanks, tanker trucks and pipelines (PDF file 94 KB) includes information on making disinfectant solutions
2. Sanitary Inspections - (PDF file 551KB) provides overview of role and activities in sanitary inspection
3. Sanitary Inspection Resources - (PDF file 487 KB) provides model forms and inspection sheets that can be used when doing sanitary inspections
4. Emergency disinfection of water supply guidelines - US EPA website outlining what to do to provide emergency disinfection
5. Chlorination Kit / Test Kit - Palintest commercial website

References

ATSIC (2002). Atlas of Health Related Infrastructure in Discrete Indigenous Communities. Aboriginal and Torres Strait Islander Commission. National Housing and Infrastructure Centre. Melbourne.

HealthHabitat. (1993). Housing for Health: Towards a Healthy Living Environment for Aboriginal. Australia. PO Box 495 Newport Beach NSW 2106. Phone: (02) 9973 1316.

NEHF. (1998). Guidance on Use of Rainwater Tanks. (PDF file 46pg)National Environmental Health Forum Monographs. Water Series No. 3. South Australian Health Commission. Adelaide.

NHMRC (1991) Australian Drinking Water Guidelines.

Pholeros, P (1997)." Energy and water required for health in housing on the AP lands" reported in Environmental Health Handbook: A Practical Manual for Remote Communities (PDF file 230pg), G. Harris (ed), Menzies School of Health Research. Northern Territory.

Territory Health Services, Public Health Strategy Unit. (1999) The Public Health Bush Book. (html for Table of Contents) Facts and approaches to three key public health issues. Department of Health and Community Services. Darwin.

WHO (1997). Guidelines for drinking-water quality. Surveillance and control of community supplies. 2nd Edition. Vol. 3. World Health Organization. Geneva.

WHO (1997). Technical cards on environmental sanitation. (PDF file 46pg) World Health Organization. Geneva.

Links for Water and Government Departments

Northern Territory	Land and Water Advisory Service Dept. of Infrastructure, Planning and Environment Environmental Health Programme Dept. Health & Community Services
South Australia	Department for Water Resources Dept. Water, Land and Biodiversity Conservation Public Health SA, Dept. Human Services
New South Wales	Natural Resource Management NSW, Dept. Infrastructure, Planning & Natural Resource Management Water Unit - Environmental Health Branch, NSW Health Dept.
Victoria	Victorian Water Resources Data Warehouse Public Health Group, Dept. Human Services
Queensland	Department of Narural Resources and Mines Queensland Health, Indigenous Environmental Health
Tasmania	Department of Primary Industries, Water and Environment Public and Environmental Health Service, Department of Health and Human Services
Western Australia	Water & Rivers Commission, West Australian Government Population Health Division, Health Department of WA

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Created October 2003
by Paul Williamson