Chlorination by-product levels in hot tap water: Significance and variability.

People are exposed to chlorinated by-products (CBPs) through the consumption of cold tap water (CTW) (ingestion, inhalation, dermal contact) but also through the use of hot tap water (HTW) in such activities as showering and bathing (inhalation, dermal contact). This study focuses on the impact of residential water heating on CBP levels in tap water. Trihalomethane (THM) and haloacetic acid (HAA) levels were measured in the CTW and HTW of 50 residences located in two distribution systems supplied by chlorinated surface water during summer and winter.