Effects of Tap Water Processing on the Concentration of Disinfection By-Products in Water People Drink

Abstract

ISEE-0665 Background and Objective: Concentration of disinfection by-products (DBP) in water varies depending on the way water is processed before consumption. The aim of this study was to examine the effects on DBP concentration of a range of common water processing methods used in daily consumption of drinking water from a public water supply system (tap water). Methods: We conducted a cross-sectional survey of DBP concentrations in tap water samples in Sydney, Australia, and 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 DBP concentrations in water ready for consumption. Four species of trihalomethanes (THMs) and nine species of haloacetic acids (HAAs) were analyzed in each sample collected. 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. 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 to 14.2%, 6.5%, 7.4% and 12.2% of tap water respectively). Fridge storage did not show any significant effect on THMs or HAAs. Jug-filtering and instant boil-filtered water resulted in large decreases (reductions to between 6% and 23%) in all species of HAAs. However refrigerator storage showed only a minimal decrease in HAAs (reduced to 90%). Conclusion: This study suggests that filtering tap water can significantly reduce the concentration of all species of DBPs, and that boiling tap water significantly reduces THMs but only some HAAs. Further research in this area using larger sample sizes is warranted to investigate explanatory factors affecting DBP concentration after various water handling strategies.