Effects of tap water processing on the concentration of disinfection by-products

Aim: This study examined the effects on disinfection by-product (DBP) concentrations of common household methods for processing drinking water. Methods: We investigated the effects of refrigerator storage, jug filtering, boiling in an electric kettle, and supply from an instant boiling water unit, with or without filtering, on four species of trihalomethanes (THMs) and nine species of haloacetic acids (HAAs) in water ready for consumption in Sydney, Australia. Water samples were processed in such a way as to simulate real life conditions for drinking filtered water or hot water drinks prepared from tap water drawn from public water supply systems. Results: There was a large reduction in total THMs in kettle-boiled water, instant boiled water, jug-filtered water and instant boiled-filtered water (reductions of 85.8, 93.5, 92.6 and 87.8% of their concentration in tap water respectively). Refrigerator storage did not appear to have a consequential effect on THMs or HAAs. Jug-filtering and instant boiling and filtering resulted in large decreases (77-94%) in all species of HAAs in tap water. Conclusion: This study suggests that different methods of processing tap water can change DBP concentration to an extent that would have a meaningful impact on exposure assessment in epidemiological studies.