3.2 Assessment of the drinking water supply system (element 2)

Components:

• Water supply system analysis

• Assessment of water quality data

• Hazard identification and risk assessment

Assessment of the drinking water supply system is an essential prerequisite for subsequent steps in which effective strategies for prevention and control of hazards are planned and implemented. This includes understanding the characteristics of the drinking water system, what hazards may arise, how these hazards create risks, and the processes and practices that affect drinking water quality.

The drinking water supply system is defined as everything from the point of collection of water to the consumer and can include:

• catchments, including groundwater systems

• source waters

• storage reservoirs and intakes

• treatment systems

• service reservoirs and distribution systems

• consumers.

Water quality can be affected at each of these points and because they are all interrelated, integrated management is essential. Generally, a drinking water supplier is only responsible for delivery of water to the consumer’s meter. However, although it is not possible to control consumers’ actions, suppliers should consider how drinking water quality may be affected in private plumbing systems and provide appropriate information to consumers.

The assessment should include the vulnerability classification of the catchment, the microbial band allocation, the required treatment required to achieve microbial safety and whether the total log reductions claimed meet those required to meet health-based targets (see Chapter 5).

Additional guidance on this element is provided in Appendix 3.