Objective To learn the change on concentrations and the health risks of some non-carcinogenic contaminants in municipal terminal piped water after the implementation of a South-to-North Water Diversion Project in a district of a city.
Methods Terminal piped water samples were collected from 21 monitoring points distributed in 15 sub-districts of the city in each month of 2014 and 2015; and the concentrations of volatile phenol, cyanide, fluoride, ammonia-nitrogen, nitrate, iron, manganese, lead, mercury, copper, zinc and selenium in tap water were monitored. The change of non-carcinogenic contaminants before and after the implementation of South-to-North Water Diversion Project was disussed.The change of the health risks of non-carcinogenic contaminants in municipal teminal piped water was evaluated by a health risk assessment model.
Results Fluoride and nitrate were decreased while iron was increased significantly after the implementation of South-to-North Water Diversion Project (P<0.05).Therefore the health risk of fluoride and nitrate were decreased while the health risk of iron was increased (P<0.05). Before and after the implementation of South-to-North Water Diversion Project, the total annual health risk of non-carcinogenic contaminants was 4.068×10-9 and 3.326×10-9 respectively (P<0.05).
Conclusion The health risk of municipal pipe water decreased significantly after South-to-North Water Diversion Project being implemented, which was much lower than the maximum acceptable level of risk recommended by USEPA and ICRP.The sanitary condition of municipal water got improved after the project being implemented.
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