Eawag, Swiss Federal Institute for Aquatic Science and Technology, Überlandstrasse 133, CH-8600 Dübendorf, Switzerland.
Water Res. 2010 Sep;44(17):4868-77. doi: 10.1016/j.watres.2010.07.032. Epub 2010 Aug 7.
Drinking water quality is routinely monitored in the distribution network but not inside households at the point of consumption. Fluctuating temperatures, residence times (stagnation), pipe materials and decreasing pipe diameters can promote bacterial growth in buildings. To test the influence of stagnation in households on the bacterial cell concentrations and composition, water was sampled from 10 separate households after overnight stagnation and after flushing the taps. Cell concentrations, measured by flow cytometry, increased (2-3-fold) in all water samples after stagnation. This increase was also observed in adenosine tri-phosphate (ATP) concentrations (2-18-fold) and heterotrophic plate counts (4-580-fold). An observed increase in cell biovolume and ATP-per-cell concentrations furthermore suggests that the increase in cell concentrations was due to microbial growth. After 5 min flushing of the taps, cell concentrations and water temperature decreased to the level generally found in the drinking water network. Denaturing gradient gel electrophoresis also showed a change in the microbial composition after stagnation. This study showed that water stagnation in household pipes results in considerable microbial changes. While hygienic risk was not directly assessed, it emphasizes the need for the development of good material validation methods, recommendations and spot tests for in-house water installations. However, a simple mitigation strategy would be a short flushing of taps prior to use.
饮用水质量在分配网络中通常会进行监测，但在家庭用户的用水点不会进行监测。温度波动、停留时间（停滞）、管道材料和不断减小的管道直径会促进建筑物内的细菌生长。为了测试家庭用户中的停滞对细菌细胞浓度和组成的影响，在隔夜停滞和打开水龙头放水冲洗后，从 10 个独立家庭中采集水样。通过流式细胞术测量，所有水样在停滞后细胞浓度增加（增加 2-3 倍）。三磷酸腺苷（ATP）浓度（增加 2-18 倍）和异养平板计数（增加 4-580 倍）也观察到了这种增加。细胞生物量和每细胞 ATP 浓度的增加进一步表明，细胞浓度的增加是由于微生物生长所致。打开水龙头放水冲洗 5 分钟后，细胞浓度和水温降低至饮用水管网中通常发现的水平。变性梯度凝胶电泳也显示停滞后微生物组成发生了变化。这项研究表明，家庭管道中的水停滞会导致显著的微生物变化。虽然没有直接评估卫生风险，但它强调需要开发良好的材料验证方法、推荐和现场测试方法，以用于家庭内部水安装。然而，一个简单的缓解策略是在使用前短暂地冲洗水龙头。
