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;

• underdosing 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 data available 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.