Biofilm detachment contributes to water quality deterioration. However, the contributions of biofilm detachment from different pipes have not been quantified or compared. Following the introduction of partial reverse osmosis (RO) in drinking water production, this study analyzed particles at customers’ ends and tracked their origins to water distribution mains and service lines. For doing so, filter bags were installed in front of water meters to capture upstream detached particles, while biofilm from water main and service line were sampled by cutting pipe specimens. The results showed that elemental concentrations of the biofilm in mains were higher than those of service lines (54.3–268.5 vs. 27.1–44.4 μg/cm²), both dominated by Ca. Differently, filter bags were dominated by Fe/Mn (77.5–98.1%). After introducing RO, Ca significantly decreased in biofilms of mains but not service lines, but the released Fe/Mn rather than Ca arrived at customers’ ends. The ATP concentrations of service lines were higher than mains, which decreased on mains but increased in service lines after introducing RO. For the core ASVs, 13/24 were shared by service lines (17), mains (21), and filter bags (17), which were assigned mainly to Nitrospira spp., Methylomagnum spp., Methylocytis spp., and IheB2–23 spp. According to source tracking results, service lines contributed more than mains to the particulate material collected by filter bags (57.6 ± 13.2% vs. 13.0 ± 11.6%). To the best of our knowledge, the present study provides the first evidence of service lines’ direct and quantitative contributions to potential water quality deterioration at customers’ ends. This highlights the need for the appropriate management of long-neglected service line pipes, e.g., regarding material selection, length optimization, and proper regulation.

生物膜脱落导致水质恶化。然而，不同管道生物膜脱落的贡献尚未量化或比较。继在饮用水生产中引入部分反渗透 (RO) 后，本研究分析了客户端的颗粒物并追踪其在配水干线和服务管线中的来源。为此，在水表前面安装了过滤袋，以捕获上游分离的颗粒，同时通过切割管道样本对主水管和供水管线中的生物膜进行取样。结果表明，干管中生物膜的元素浓度高于供水管中的生物膜元素浓度（54.3–268.5 vs. 27.1–44.4 μg/cm ²），两者均以 Ca 为主。不同的是，滤袋主要由铁/锰 (77.5–98.1%) 组成。引入RO后，干线生物膜中Ca显着下降，但服务线生物膜中Ca显着下降，但释放的Fe/Mn而不是Ca到达用户端。服务线ATP浓度高于干线，引入RO后干线ATP浓度下降，服务线ATP浓度上升。对于核心 ASV，13/24 由服务线 (17)、干线 (21) 和过滤袋 (17) 共享，主要分配给硝化螺旋菌属、甲基巨藻属、甲基细胞属属和IheB2-23种。根据源跟踪结果，供水管道对过滤袋收集的颗粒物质的贡献大于管道（57.6 ± 13.2% vs. 13.0 ± 11.6%）。据我们所知，本研究首次提供了服务线路对客户端潜在水质恶化的直接和定量贡献的证据。这凸显了对长期被忽视的服务管线管道进行适当管理的必要性，例如，在材料选择、长度优化和适当调节方面。