Guidance on use of rainwater tanks

11. Community-based supplies

Page last updated: March 2011

Community-based drinking water supplies need a higher level of management than those to individual dwellings.

Operators/managers of community-based supplies need to implement more formal documented management plans to assure quality. In addition, in Australia, drinking water is regarded as a food and may be subject to either general food legislation or specific drinking water legislation. Operators of community supplies should contact relevant health authorities to determine requirements under state/territory legislation.

If rainwater is supplied for purposes other than drinking and food preparation, this must be clearly indicated on all taps.

The principles discussed in Section 3 are relevant to community-based supplies, but compared to the management of rainwater tanks used in individual dwellings, a greater surety is required due to the potential exposure of larger numbers of people. The need for surety is further increased if rainwater tanks are used in facilities such as nursing homes, hospitals or in food premises. Use of continuous disinfection, for example, through installation of a monitored ultraviolet light system could be required to provide assurance of water quality.

Documented management plans for community supplies should include a flow diagram of the system (catchment area, storage tanks, pipework, tap locations) together with a description of preventive measures, monitoring and corrective actions, as well as evidence that these requirements have been met. In addition, while preventive management and maintenance procedures should always remain the primary focus for assuring water quality there is a need for some verification that the overall plan works effectively.

A traditional approach to verification is regular testing for the faecal indicator, E. coli. The frequency of testing (for example, weekly or monthly) will depend on the size of the population serviced by the supply, whether water supplied from tanks is treated, the costs and logistics involved in getting samples to a testing laboratory, and the risk management procedures that are in place. For example, installation of a monitored ultraviolet light disinfection system could lessen the required frequency of testing. If E. coli is detected, remedial action will be required. This could include chlorination of the rainwater tank. The presence of E. coli in a disinfected supply indicates inadequate treatment and the need for improved performance.

If a community-based supply is in an area subject to industrial emissions or high levels of urban traffic, chemical testing could also be warranted.

Further information on requirements for management of water quality is available in the ADWG.