Objective To investigate the concentration of trichloromethane in drinking water from centralized water supply and evaluate its health risk in Suzhou, China.

Methods From 2018 to 2022, samples of finished water, terminal water, and secondary water were collected to monitor the level of trichloromethane in Suzhou. The health risk of trichloromethane exposure via drinking water for people was assessed according to the model recommended in the Technical Guide for Environmental Health Risk Assessment of Chemical Exposure (WS/T 777-2021).

Results A total of 2 610 water samples were collected, and the concentration of trichloromethane ranged from not detected to 57.00 μg/L, with a median (M) of 8.00 μg/L, and the qualified rate was 100%. During the study period, the trichloromethane concentration in the wet season was significantly higher than that in the dry season (P < 0.01); terminal water had a significantly higher trichloromethane concentration than finished water and secondary water (P < 0.01); the level of trichloromethane was significantly lower in drinking water disinfected with monochloramine than that in drinking water disinfected with liquid chlorine and sodium hypochlorite (P < 0.01); and drinking water from rivers had a significantly higher trichloromethane level than that from lakes (P < 0.01). The carcinogenic risk of exposure to trichloromethane via drinking water was from 0.45×10^-5 to 3.02×10^-5 for male population and from 0.46×10^-5 to 3.03×10^-5 for female population.

Conclusion The concentration of trichloromethane in drinking water from centralized water supply is qualified in Suzhou, with a low health risk via drinking water for people.