Monitoring Results Analysis for Drinking Water Quality in Mianyang, Sichuan Province, China, 2019

Objective To analyze the hygienic status of domestic drinking water in Mianyang, Sichuan province, China, in 2019, to investigate the key indicators affecting the water hygiene, and to identify the unqualified indicators to ensure the safety of drinking water.

Methods A total of 1 346 samples of drinking water were examined in terms of microbes, toxicological indicators, sensory properties, and general chemical indicators, etc., according to the Standard Examination Method for Drinking Water (GB/T 5750-2006).The result were evaluated according to the Standards for Drinking Water Quality (GB 5749-2006).

Results The main source of the monitored water samples was river water, and the main water treatment method was complete treatment.The equipment and the standard operation for disinfection facilities in urban areas were better than those in rural areas. The qualified rate of the 1 346 water samples was 70.36%(947/1 346).The qualified rate was 96.19% (202/210) in urban areas and 65.58%(745/1 136) in rural areas, with a significant difference between them(χ²=79.62, P < 0.05). The qualified rates of water samples treated completely, treated by sedimentation filtration alone, disinfected alone, and untreated were 73.02%(552/756), 0%(0/36), 62.37%(184/295), and 18.37%(9/49), respectively, with a significant difference among different treatment method (χ²=136.84, P < 0.05).The qualified rates of water samples from large and small rural centralized water supply projects were 81.27%(217/267) and 60.76%(528/869), respectively, with a significant difference between them(χ²=38.08, P < 0.05).The qualified rates in terms of total coliform, Escherichia coli, free chlorine, and chlorine dioxide were relatively low in rural drinking water.

Conclusion The qualified rate of drinking water in urban areas is significantly higher than that in rural areas in Mianyang. Microbes and disinfection indices were the key indicators of drinking water monitoring. Strengthening water source protection and disinfection management is an important measure to improve the qualified rate of water quality.