Department of Civil Engineering, Polytechnique Montréal, Montréal, QC, Canada.
INRS-Institut Armand-Frappier, Laval, QC, Canada.
PLoS One. 2018 Jun 21;13(6):e0199429. doi: 10.1371/journal.pone.0199429. eCollection 2018.
Microbial drinking water quality can be altered in large buildings, especially after stagnation. In this study, bacterial profiles were generated according to the stagnation time and the volume of water collected at the tap. Successive volumes of cold and hot water were sampled after controlled stagnation periods. Bacterial profiles revealed an important decline (> 2 log) in culturable cells in the first 500 mL sampled from the hot and cold water systems, with a steep decline in the first 15 mL. The strong exponential correlation (R2 ≥ 0.97) between the culturable cell counts in water and the pipe surface-to-volume ratio suggests the biofilm as the main contributor to the rapid increase in suspended culturable cells measured after a short stagnation of one-hour. Results evidence the contribution of the high surface-to-volume ratio at the point of use and the impact of short stagnation times on the increased bacterial load observed. Simple faucets with minimal internal surface area should be preferred to minimize surface area. Sampling protocol, including sampling volume and prior stagnation, was also shown to impact the resulting culturable cell concentration by more than 1000-fold. Sampling a smaller volume on first draw after stagnation will help maximize recovery of bacteria.
微生物饮用水水质在大型建筑物中可能会发生变化，尤其是在停滞之后。在这项研究中，根据停滞时间和从龙头收集的水量来生成细菌图谱。在经过控制的停滞期后，连续采集冷热水的样本。细菌图谱显示，在从冷热水系统中采集的前 500 毫升水样中，可培养细胞数量显著下降（>2 对数），在前 15 毫升中急剧下降。水和管道表面积与体积比之间的可培养细胞计数的强指数相关性（R2≥0.97）表明，在短时间（一小时）的停滞之后，生物膜是悬浮可培养细胞快速增加的主要原因。结果表明，在使用点处高表面积与体积比以及短停滞时间对观察到的细菌负荷增加的贡献。应优先选择内部表面积最小的简单水龙头，以尽量减少表面积。采样方案，包括采样体积和先前的停滞，也被证明会使最终可培养细胞浓度增加超过 1000 倍。在停滞后第一次抽取时采集较小的体积，将有助于最大限度地回收细菌。
