The use of traditional drinking water microbial quality monitoring methods, including heterotrophic plate counts (HPCs) and total coliform counts, are not only laborious and time-consuming but also do not readily allow identification of risk areas in the network. Furthermore, if areas of concern are identified, and mitigation measures are taken, it takes days before the effectiveness of these measures is known. This study identified flow cytometry (FCM) as an online sensor technology for bacterial water quality monitoring in the distribution network. We monitored the total bacterial cell numbers and biodiversity in a drinking water distribution system (DWDS) using an online FCM. Two parallel online FCM monitoring systems were installed on two different locations at a drinking water treatment plant (DWTP; Saudi Arabia) supplying chlorinated water to the distribution and in the network 3.6 km away from the DWTP. The FCMs were operated at the same time in parallel to assess the biological stability in DWDSs. The flow cytometric data was compared with the conventional water quality detection methods (HPC and total coliforms). HPC and total coliforms were constantly below the detection limits, while the FCM provided detectable total cell count data and enabled the quantification of changes in the drinking water both with time and during distribution. Results demonstrate the value of FCM as a tool for compliance monitoring and risk assessment of DWDSs.

传统饮用水微生物质量监测方法的使用，包括异养菌板数（HPC）和大肠菌群总数，不仅费时费力，而且不易识别网络中的危险区域。此外，如果确定了关注的领域并采取了缓解措施，则需要几天的时间才能知道这些措施的有效性。这项研究确定流式细胞仪（FCM）作为在线传感器技术，用于监控分配网络中的细菌水质量。我们使用在线FCM监控了饮用水分配系统（DWDS）中的细菌总数和生物多样性。两个并行的在线FCM监控系统安装在饮用水处理厂（DWTP; 沙特阿拉伯）向配电网和距离DWTP 3.6公里的网络供应氯化水。FCM同时运行，以评估DWDS中的生物稳定性。将流式细胞仪数据与常规水质检测方法（HPC和总大肠菌群）进行了比较。HPC和总大肠菌群始终低于检测极限，而FCM提供可检测的总细胞计数数据，并能够定量分析饮用水随时间和分布的变化。结果表明，FCM作为DWDS遵从性监控和风险评估工具的价值。将流式细胞仪数据与常规水质检测方法（HPC和大肠菌群）进行了比较。HPC和总大肠菌群始终低于检测极限，而FCM提供可检测的总细胞计数数据，并能够定量分析饮用水随时间和分布的变化。结果表明，FCM作为DWDS的合规性监视和风险评估工具的价值。将流式细胞仪数据与常规水质检测方法（HPC和总大肠菌群）进行了比较。HPC和总大肠菌群始终低于检测极限，而FCM提供可检测的总细胞计数数据，并能够定量分析饮用水随时间和分布的变化。结果表明，FCM作为DWDS的合规性监视和风险评估工具的价值。