Objective Through monitoring the quality of drinking water in 2009-2016 to understand the present situation and the trend of water security and water quality in Nantong.

Methods The finished water from rural waterworks and tap water in dry season and wet season in 2009-2016 were collected and analyzed according to the requirement of the Standard examination methods for drinking water (GB/T 5750-2006). Conventional indicators for drinking water and ammonia nitrogen in water were tested.

Results The qualified rate of drinking water for each year from 2009 to 2016 in dry season were 67.56%, 69.5%, 75.4%, 81.5%, 79.9%, 97.64%, 98.43% and 99.79%, and those in wet season were 55.34%, 66.9%, 73.9%, 78.6%, 95.3%, 95.27%, 97.07% and 99.38% respectively; the qualified rate was in a rising trend (χ²=339.42, P < 0.05 and χ²=468.3, P < 0.05). The passing rate of surface water for each year from 2009 to 2016 were 73.00%, 87.07%, 92.36%, 97.22%, 100%, 97.22%, 97.72% and 97.22%, and the passing rate of groundwater water were 58.73%, 63.10%, 68.30%, 66.80%, 71.80%, 75.00%, 100% and 100%, respectively, and the passing rate were also in a rising trend (χ²=163.20, P < 0.05 and χ²=27.343, P < 0.05). The proportion of population suffered from unsafe drinking water in 2009-2016 were 58.52%, 32.52%, 20.16%, 10.49%, 0.81%, 0.72%, 1.85% and 0.36%. The coverage of unsafe water was declined year by year (χ²=70.921, P < 0.05).

Conclusions Rural drinking water quality was increased year by year, and the coverage of unsafe drinking water was reduced year by year. The main unqualified indexes were the total number of colony and disinfectants.