Halogenated DBP concentrations in a distribution system

Abstract

With increasing residence time, concentrations of THMs increased, but concentrations of HANs, HKs, CP, and HAAs decreased. Increases in the concentration of disinfection by‐products (DBPs) with increasing residence time in distribution systems have been predicted from laboratory studies but not conclusively demonstrated in the field. DBP concentrations were measured in a central New Jersey water distribution system during one year at four locations with nominal water residence times of zero, one, two, and at least three days. The water was disinfected with chloramine so that finished water left the plant with a free chlorine residual of 0.5 mg/L. Concentrations of trihalomethanes (THMs) increased with increasing residence time in the distribution system, but the concentrations of haloacetonitriles, haloketones, chloropicrin, and haloacetic acids decreased with increasing residence time. Concentrations changed more rapidly during warm months than cold months; temperature and chlorine residual were the most important parameters controlling DBP concentrations.