| Objective:The objectives of this study were to know the water quality of secondary water supply, the situation of the health management and the condition of the facilities of water supply in Chongming County. In addition, we also want to know the factors correlate with the quality of secondary water supply. Beside these, we also want to compare the water quality of secondary water supply system and the municipal water supply system.Methods:The study was conducted between June and October of2012. Convenience sampling was used to select60residential areas in Chongming County. In order to know the water quality, the water related health management and the facilities of water supply, questionnaire based face-to-face interviews were conducted. Also, the methods for compare secondary water supply system and municipal water supply system were established. The interviews were conducted at both baseline and the follow-up period. Also, water samples were collected and tested for both secondary water supply system and municipal water supply system at each selected residential areas. Data were double-entered using EpiData3.0. Logic checking was used to clean the data. After the re-assignment and generate of new variables, SPSS13.0was used to do the data analysis.Results:A total of120water samples (60for secondary water supply system and60for municipal water supply system) were collected and tested for the60residential areas. The study found that there are128set of secondary water supply residential area, with1217secondary water supply tank and48secondary water supply impounding reservoir in Chongming. The qualification rate of secondary water supply is significant lower than the rate of municipal system (75.00%VS.93.33%, P<0.05). Besides this, the total coliforms, total number of colonies, the pH, aluminum, zinc and total hardness of secondary water supply system were also significant higher than the municipal system (P<0.05). However, compared to the water of municipal system, the secondary water supply system has significant lower level of chlorine dioxide (P <0.05). Our study also found that six indicators of water qualities (total number of colonies, turbidity, smell and taste, iron and chlorine dioxide) were unqualified in Chongming county. The secondary water supply system has significant higher unqualified rate of total coliforms and chlorine dioxide than the municipal water supply system (6.67%VS0.00%, P<0.05). The multivariate logistic regression shown that the levels of source of water supply and frequency of regularly tank cleaning were significantly correlated with the water quality of secondary water supply system (P<0.05),(OR for the levels of source of water supply was0.075, with95%CI:0.010-0.571, OR for regularly tank cleaning was0.015, with95%CI:0.001-0.184).Conclusion:The water quality, its related health management and the condition of the facilities of water supply in Chongming county is far away from the requirements of the laws, regulations and standards requirements. Compare to the municipal water supply system, the secondary water supply system has higher unqualified rate. The microbiological indicators, turbidity, and disinfectants margin (chlorine dioxide) were the main unqualified indexes. Beside these, the levels of source of water supply and the frequency of regularly tank cleaning were two factors that significantly correlated with the water qualify of Chongming. Combined these together, the risk of emergency events for water contamination may increasing in Chongming. All of these illustrated that we should cooperate with the other departments to improve the water quality of secondary water supply system, and to reduce the events of water contamination. |
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