Lehtola Markku J, Miettinen Ilkka T, Hirvonen Arja, Vartiainen Terttu, Martikainen Pertti J
Laboratory of Environmental Microbiology, National Public Health Institute, Department of Environmental Health, P.O. Box 95, FI-70701, Kuopio, Finland.
Laboratory of Environmental Microbiology, National Public Health Institute, Department of Environmental Health, P.O. Box 95, FI-70701, Kuopio, Finland.
Int J Hyg Environ Health. 2007 Dec;210(6):725-732. doi: 10.1016/j.ijheh.2006.11.011. Epub 2007 Jan 16.
The numbers of bacteria generally increase in distributed water. Often household pipelines or water fittings (e.g., taps) represent the most critical location for microbial growth in water distribution systems. According to the European Union drinking water directive, there should not be abnormal changes in the colony counts in water. We used a pilot distribution system to study the effects of water stagnation on drinking water microbial quality, concentration of copper and formation of biofilms with two commonly used pipeline materials in households; copper and plastic (polyethylene). Water stagnation for more than 4h significantly increased both the copper concentration and the number of bacteria in water. Heterotrophic plate counts were six times higher in PE pipes and ten times higher in copper pipes after 16 h of stagnation than after only 40 min stagnation. The increase in the heterotrophic plate counts was linear with time in both copper and plastic pipelines. In the distribution system, bacteria originated mainly from biofilms, because in laboratory tests with water, there was only minor growth of bacteria after 16 h stagnation. Our study indicates that water stagnation in the distribution system clearly affects microbial numbers and the concentration of copper in water, and should be considered when planning the sampling strategy for drinking water quality control in distribution systems.
配水管网中的细菌数量通常会增加。家庭管道或水配件（如水龙头）往往是供水系统中微生物生长的最关键位置。根据欧盟饮用水指令，水中菌落数不应有异常变化。我们使用了一个中试配水系统，研究了水停滞对饮用水微生物质量、铜浓度以及家庭中两种常用管道材料（铜和塑料（聚乙烯））生物膜形成的影响。水停滞超过4小时会显著增加水中的铜浓度和细菌数量。停滞16小时后，聚乙烯管中的异养平板计数比仅停滞40分钟后高六倍，铜管中则高十倍。在铜质和塑料管道中，异养平板计数的增加与时间呈线性关系。在配水系统中，细菌主要源自生物膜，因为在水的实验室测试中，停滞16小时后细菌仅有少量生长。我们的研究表明，配水系统中的水停滞明显影响水中的微生物数量和铜浓度，在规划配水系统饮用水质量控制的采样策略时应予以考虑。
