Disinfection by-products in Canadian drinking water

Halogenated disinfection by-products were determined in Canadian drinking water supplies where chlorine was used at some stage in the treatment process. The effects of applied disinfectants (chlorine, chloramine and ozone), seasonal variation (winter and summer) and spatial variation (treatment plant and distribution system) were examined. Chloroform, dichloroacetic acid and trichloroacetic acid were the major disinfection by-products found in all treated water samples and total haloacetic acid concentrations often equalled or exceeded total trihalomethane concentrations. Haloacetonitriles, halopropanones, chloral hydrate and chloropicrin were usually detected in treated water samples but at lower concentrations.