DBPS IN CHLORINATED NORTH-CAROLINA DRINKING WATERS

The proposed Disinfectants/Disinfection By-products (D/DBP) Rule establishes a maximum contaminant level (MCL) for haloacetic acids (HAAs) of 60 mu g/L and revises the MCL for trihalomethanes (THMs) to 80 mu g/L. In anticipation of the proposed rule, researchers obtained finished drinking water from six North Carolina utilities and analyzed for THMs, HAAs, and total organic halides. Samples from representative locations within the distribution system were collected three times over 12 months to discern seasonal patterns in DBP formation. Relationships among the different by-products were explored, as was their relationship to raw water quality. The results suggest that HAA concentrations can be as much as 50 percent greater than THM concentrations and that the occurrence of HAAs in finished drinking water may be much higher than was anticipated when the D/DBP Rule was proposed.