Objective To investigate bacterial contamination and related impact factors of treated water from household water purify system in Shanghai.
Methods A total of 320 households were selected in Shanghai and tap water treated by purify system were multiple sampled for seasonal microbial contamination determination including total bacterial count, coliform, and bacterial spectrum. The information on system life span, system components, daily usage, and maintenance were also collected. Rank sum test, χ2 test, and logistic regression model were used for data analysis.
Results Microbial contamination was common among the investigated water purifiers and varied by season. In summer, the contamination level was higher than that in autumn and winter. In the same season such as summer or autumn, the microbial contamination level of systems with reverse osmosis treatments was higher than that of the other systems; however, there was no significant difference found in winter. The results of bacterial spectrum analysis indicated pathogens or opportunistic pathogens, such as Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus cereus, in treated water samples with total bacterial counts over 20 cfu/mL. The main impact factors affecting bacterial contamination in treated water from water purify system were UV treatment unit, system life span, and filter life span and running frequency.
Conclusion The quality of household water purify system's design, components, and instruction manual, as well as appropriate usage and maintenance, are the key elements of water safety. Quality supervision and promotion of proper usage and maintenance should be strengthened.
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