Water quality monitoring on rural centralized water supplies in Guangxi,2008-2012

Objective To understand the quality of water in centralized water supplies in Guangxi rural areas, and provide data for the government to manage drinking water safety. Methods Data on water quality in rural areas of Guangxi in 2008-2012 were exported from The National Disease Control Information System. Data on centralized water supply factories were collected from literature review or onsite surveys. Water samples were collected, tested and evaluated according to GB/T5750-2006 and GB 5749-2006. Results Centralized water supply factories in Guangxi rural areas were mostly small-scale with the capacity of daily water supply less than 1000 m3.The small-scale water supply factories accounted for over 91% of the centralized water supply. The main type of water source was river/stream water, which accounted for over 64.17% of all water sources for the centralized water supply systems. The proportions of the water supply factories with complete treatment or simple disinfection increased year by year, although in some factories the disinfection equipments were occasionally run or do not run at all. the quality of centralized supplied water increased year by year(χ2= 1 727.414, P 0.01), and the qualified rate of water rose form 22.98% in 2008 to 49.26% in 2012. The qualified rate of water directly sampled from factories was higher than that from tap water, and the qualified rate of water sampled in dry season was statistically higher than that in flooding season. In comparison with the other factors microbial contamination made more water samples unqualified. Conclusions Most of centralized water supply factories in Guangxi rural areas are small-scale, and poor treatment. The major cause for the unqualified water is microbial contamination.