Formation and evolution of haloacetic acids in drinking water of Beijing City.

The formation and evolution of haloacetic acids (HAAs) in drinking water were examined in five water treatment plants in Beijing City, China. It was found that HAAs in water increased due to prechlorination and postchlorination. The conventional treatment processes removed the HAAs in less than 20%. By comparison, activated carbon bed removed 49-86% of HAAs and was considered to be an effective treatment unit for HAAs removal. The HAAs concentration in distribution system was associated with water sources, especially the total organic carbon in raw water, while its fluctuation appeared small.