N-nitrosodiumdimethylamine (NDMA) in drinking water is one of many factors – such as a persons’ genes – that cause cancer. Although NDMA is not a sole cause of cancer, the water industry aims to minimise its contribution to illness and disease. This research measured levels of NDMA in drinking and recycled waters and found the majority well below the Australian Drinking Water Guideline values that are considered safe for public consumption. Different sources of NDMA were identified and water monitoring and treatment strategies to optimise NDMA removal from source waters were recommended.

Components of dissolved organic matter (DOM) and dissolved organic nitrogen (DON) in source waters can react with disinfecting chlorine or chloramine to form nitrogenous disinfection byproducts (n-DBPs) which might be toxic and hazardous to health. In this research, water samples were collected from nine water treatment plants and found to contain 28 n-DBPs. Total n-DBP formation, and particularly brominated n-DBP formation, was affected more by the levels of bromine in raw water than the different forms of nitrogen, and this led to the recommendation that it could be beneficial to monitor raw waters with high bromine concentrations. Although chloramination caused formation of more n-DBPs than chlorination, coagulation treatment decreased total DBP levels. Further research was recommended to characterise the toxicity of n-DBPs and to optimise the removal of DOM, DON and other n-DBP precursors by using GAC Acticarb in the treatment train.

Water is disinfected to remove harmful microbes and pathogens such as cholera and typhoid. The problem is that disinfection of certain types of waters, such as those containing naturally high levels of bromide or iodide, can cause the formation of disinfection by-products (DBPs). Some DBPs have been linked to cancer although this association is relatively weak because many other factors have a much stronger influence on the development of cancer than drinking water. Nevertheless, the water industry aspires to minimise this risk and conducted this research to measure the levels of bromide, iodide and other substances in Australian source waters. A number of treatments with potential to remove bromide were examined, and it was found that chlorination reduced the risk posed by iodo-DPBs.

This project developed analytical methods sensitive enough to detect the very low levels of compounds that leach out of old coal tar enamel-lined pipes, then catalogued the chemicals and the levels they were found at in a problematic pipeline. One of the chemicals leaching out of the old lining is probably acted on by microbes to produce another substance with an earthy, musty flavour. None of these were toxic in tests and they are therefore unlikely to pose a risk to human health.