After water has been treated to protect public health, improve aesthetics by removing colour and taste and odour as required, it is ready to be delivered to consumers. The system of mains and pipes used to deliver the water is known as the distribution, or reticulation, system.
Treated water may be held at a treatment plant or immediately discharged into the system of mains and pipes that will transport it to consumers’ taps. On the way it may be held in short-term storages, usually known as service reservoirs, which are located as close as possible to where the water will be used.
Sufficient water is required in a local area to supply periods of high demand, as on a hot summer day. From a design perspective, the needs of fire services usually determines the capacity of the system.
An important characteristic of a drinking water distribution system is that it is closed, to prevent contamination by birds, animals or people. In contrast, irrigation water is usually delivered in open channels or aqueducts.
A significant part of the water supply system lies buried underground. Out of the public eye, such infrastructure can be overlooked. It is easy to forget how valuable and essential water distribution systems are to the community. In terms of money spent on supplying water in Australia, most of it has been invested in the mains and pipes buried under the streets of towns and suburbs across the country.
Most distribution systems have developed and expanded as urban areas have grown. A map of a water distribution system would show a complex mixture of tree-like and looped pipe networks, together with valves and pumps.
Distribution systems require regular cleaning (flushing and scouring), maintenance and a program to replace pipes and other equipment as they near the end of their useful lives. Water mains can be expected to have a useful life of 40 to 100 years. Many of the pipes under the older parts of our cities may be towards the upper end of this range.
In future, it is possible that many Australian communities will be supplied with water of two qualities: one of drinking water quality and the other of a quality that is not safe for drinking but which is suitable for other purposes such as toilet flushing and outdoor use.
Such dual systems have been used in other parts of the world and in recent years have been trialed in Australia. For example, in Sydney, New South Wales, a new housing development at Rouse Hill has been built with a dual pipe system. More recently, housing developments at Newhaven and Mawson Lakes in Adelaide, South Australia have also featured duel pipe systems.
This system has the advantage of using less high quality water where lower quality water will do, but it is difficult and expensive to dig up existing suburbs and install dual pipe systems. In addition, there are public health risks if cross-connections occur between the two systems.
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Cross-connections If a connection is accidentally made between a pipe carrying high quality drinking water and water of low quality, the drinking water can be contaminated. Most cross-connections occur when a backflow of contaminated water mixes with the water in a supply pipe. This usually happens when the drinking water supply is at a lower pressure than the contaminated source. A range of devices has been developed to limit the potential for backflow and cross-connections. Standards Australia has several Australian/NZ standards to manage backflow/cross-connections. Another possible source of contamination is a fall in distribution system pressure, which allows contaminated groundwater to enter the system through the gap in a joint or other similar route.
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Most Australians live in cities where large investments have been made to ensure an adequate supply of water, even in time of drought. Approximately seventy per cent of Australians live in cities containing more than 100,000 people. These cities represent less than one per cent of the area of Australia. The other ninety-nine per cent of this large land contains the other thirty per cent of Australians. Many of those people live in smaller cities and towns and also have an adequate mains water supply. However, some do not.
For communities not connected to mains water supply, some provision for the supply of water is essential. This could be, for example, groundwater, stored rainwater or a combination of both.
The safe use of a private water supply is discussed under Urban Water Systems
However for many small communities in remote parts of Australia, the provision of an adequate supply of water is a major challenge. Many of these communities are Aboriginal and Torres Strait Islander communities.
Many of these communities still have inadequate water supplies and some do not have a reticulated water supply at all. The provision of water services to small remote communities is particularly difficult. The remoteness makes it slow and expensive to get materials delivered. It also makes it difficult to get maintenance teams and support services on site.
For the communities themselves, on-going maintenance and repairs to water supply systems is difficult because community members generally lack access to the required technical training and to the specialised services that might be needed.
Water provision in Aboriginal and Torres Strait Islander communities was the subject of a Human Rights and Equal Opportunity Commission Report in 1994. The Report recognised the practical difficulties associated with the provision of adequate water services to remote communities and acknowledged that government departments and agencies had made efforts to improve water supplies in remote Indigenous communities. However, it concluded that no significant improvement in Aboriginal living conditions would occur without a number of other developments. These included:
In the Report, the Federal Race Discrimination Commissioner stated:
"If equality is assessed on outcomes (not inputs or the stages leading to the outcome), useful options are created for the consideration of the water supply. It is now possible to ask whether the desirable outcome is going to be a reticulated water supply which delivers water that meets NHMRC Guidelines or whether it is that people have free and unimpeded access to water supply which they can afford and over which they can exercise control to the extent of adjusting the system to suit their changing circumstances"
The Report argued that it was important to ensure that water was safe to drink but that it was also important that Aboriginal and Torres Strait Islander people were able to make their own decisions about how it was provided and maintained.
Progress made in the light of the recommendations contained in the Commission's 1994 report was reviewed on behalf of the Federal Government in 2001. That review is available at
www.hreoc.gov.au/racial_discrimination/report/water_report/index.html
The CRC for Water Quality and Treatment has an active involvement with a number of remote Indigenous communities, providing scientific and technical advice in support of their efforts to achieve improvements with their water supply. In these activities the CRC works closely with many other organisations and in particular with the Centre for Appropriate Technology in Alice Springs
Further information on the Centre for Appropriate Technology is available at
Consumer's Guide to Drinking Water - May 2006 [an error occurred while processing this directive]