Study On Risk Assessment On Centralized Rural Water Supply Systems In Changping District Of Beijing And The Application Of Water Safety Plan

The study is to identify and assess the existing risk factors in rural centralized water supply systems, identify the critical control points and propose control measures through investigation of the basic information and water quality status quo of rural dinking water supply system in Changping District of Beijing in line with the risk assessment methods recommended by WHO Water Safety Plans (WSPs), so as to ensure the safety and sanitation of rural drinking water.ObjectivesTo have a good command of the current status of drinking water sources, types of water supply and water quality through survey of the basic information about rural drinking water system in Changping; to master the rural centralized water supply facitlities and water quality risk factors in Changping; to conduct risk assessment of rural drinking water and pilot study of WSPs so as to provide solid evidence for rural drinking water management improvement in Changping District.MethodsBased on the mastery of the current status of rural drinking water in Changping,40centralized rural water plants with underground water as source water has been selected randomly for drinking water risk study, and water quality tests have been conducted in these40plants in both dry and rainy seasons, including water from plant outlet and end-users; water testing results are combined with the sanitary inspection results for full analyses and identification of risk factors in rural water supply in Changping district and proposing of corresponding control measures. Based on the whole process above,1water plant is selected for water safety plan pilot and assessment of the control effect.Results1. Current status of drinking water in Changping:the water plants with surface water as the source cover only0.15%of the total population, whereas water plants with underground water as source provide water for99.85%of the population in Changping. Centralized rural water supply provided99.99%of the population for water, among which fully treated, partially treated and untreated water coverage are68.63%,7.79%and23.57%respectively; decentralized water facilities exist only in2villages, providing water for mere42people, and all are manpower pumping.2. Among the40surveyed water plants, the proportion of risk existing is higher in no records of disinfection, no sanitation permit, no water plant design data. The rate of not rinsing pipelines after maintenance, water well less than100meters deep, households using water storage tanks, having water tanks or towers, disinfection facilities not in use, complete cleanout once over one year, no water staff operation guideline and other factors happening is about50%.3. A total of160samples of drinking water have been collected the whole year during the study, the rate of water quality meeting the standards value is47.50%. The samples of water from water plant outlet are80, with40each for dry and rainy seasons and50%meeting water quality standard value. The samples from end-users are80as well, with40each for dry and rainy seasons, yet only36samples tested with the results meeting the standard value, taking only45%. Apart from the parameters such as total coliform, E coli, turbidity, total hardness, mercury, fluoride, nitrate nitrogen, iron and zinc exceeding the standard value, other parameters are all qualified.1to4parameters of turbidity, total harness, fluoride, nitrate nitrogen, iron and zinc value exceeding the standards. In5water plants with disinfection facilities, the disinfectant residual does not meet the criteria in the guidelines.4. The impact of different factors on water quality:Out of the water source factors, the depth of well is of significant impact one water quality from plant outlet,(x2=11.667, P=0.001); whether there are storage tanks/towers has no significant impact on water quality (χ2=0.808, P=0.5); Whether there are disinfection facilities has significant impact on water quality, and for the water plants with disinfection equipment, the rate of water meeting the standard value is higher than those without disinfection facilities.(χ2=8.811, P=0.012); The rate of water meeting the standard value for both outlet and end-users have showed no significant different in dry and rainy seasons.5. The Yangfang Water Plant has been selected for WSP pilot implementation. The pilot study has found3risk factors having significant impact on water quality, and counter measures have been developed targeting the3factors. By increasing the checking frequency, water source pollution risks are reduced; enhancing the testing of disinfectant and it residuals has ensure the sufficient doses of residual in water; rules on clean water rinsing and pipeline checking has been put down; and pre-plans have been developed aiming at drinking water emergencies. One year before the implementation of WSP in the plant,965samples have been tested, with942samples meeting the standards, accounting for98.0%; after the pilot,464samples are tested, with all464samples meeting standard value, accounting for100%.ConclusionThrough the assessment, I have understand the risk factors of centralized water supply with underground water as the source water in rural areas in Changping; based on this, the application of WSP has improved the rate of ensuring the water quality.