Hygienic quality of drinking water in Zhouqu county:an investigation after the flood and the mud-rock flow disaster

Objective To evaluate the quality and the safety of drinking water in Zhouqu county after the flood and mud-rock flow disaster.Methods Fifteen drinking water sources were tested in Zhouqu county.The drinking water samples were collected and determined.Disinfection was performed for the water sources which failed to meet the safety standards.Results The qualification rate of the drinking water sources was 80.0%.Higher ammonia-nitrogen and nitrite-nitrogen concentrations(0.5 g/L and 0.03 g/L,respectively) were observed in 6.7%(1/15) of the water sources.Visible substances were found in 13.3%(2/15)of the water sources.The concentrations of residual chlorine and free residual concentration were 0.75 mg/L(0.60-1.00 mg/L) and 0.53 mg/L(0.40-0.70 mg/L) respectively after the disinfection.Conclusion Protection and disinfection of the drinking water source can guarantee the drinking safety of the residents in the disaster area.