Objective To evaluate the human health risk of chloroform and carbon tetrachloride in municipal water supply in Hebei province, China.

Methods The monitoring data of chloroform and carbon tetrachloride in municipal water supply of Hebei province from 2017 to 2021 were collected. An environmental health risk assessment model was applied to evaluate the carcinogenic risk and chronic non-carcinogenic risk of the two substances at mean concentrations. Stratified analyses were carried out for different water seasons, sample types, water sources, and regions. The result of different years were tested for trend.

Results The mean concentrations of chloroform and carbon tetrachloride in 12 578 water samples were 6.14×10^-3 and 1.07×10^-4 mg/L, respectively, and the carcinogenic risk was 3.75×10^-6 for chloroform and 1.48×10^-7 for carbon tetrachloride. The chronic non-carcinogenic risks of both chemicals were less than 1. For chloroform, the health risk was higher in wet season than in dry season, higher in surface water than in underground water, and higher in terminal water and secondary water than in finished water. For carbon tetrachloride, the health risk was higher in underground water than in surface water, and higher in finished water than in terminal water and secondary water. The health risk of chloroform increased year by year, while that of carbon tetrachloride showed a downward trend. The health risks differed between regions.

Conclusion In municipal water supply of Hebei province from 2017 to 2021, the carcinogenic risk was acceptable for chloroform and low for carbon tetrachloride, and the chronic non-carcinogenic risk was acceptable for both chemicals.