Delivering quality-changed water often contributes to the biological instability of drinking water distribution systems (DWDS). However, the potential effects of quality-changed water on the biostability within DWDS are not well understood, especially after water switching to quality-improved water. The objective of this study was to investigate the effects of quality-improved water on DWDS, focusing on the stability of biofilm. The practical aged-pipe was assembled into pipe reactors to simulate the effect of switching to quality-improve water. The adenosine triphosphate (ATP) concentration of bulk water in the pipe reactors increased from ∼1.2 ng/L to almost above 5 ng/L when fed water switching to TP 2. Biomass quantified by measuring ATP concentration confirmed that the risk of biofilm release through aged cast-iron (CI) pipe surfaces after water source switching. The changes in water characteristics due to quality-improved water source could cause bacteria release in DWDS at the initial period (at the first 7 days). However, the DWDS can establish the new stable phase after 42 days. Over time, biomass in the bulk water of the distribution system decreased significantly (The ATP concentration in the bulk maintains around 3 ng/L) after 42 days, indicating the improvement of water quality. The biofilm was dominated by bacteria related to iron-cycling process, and at the genus level, Desulfovibrio had the highest relative abundance, however, it decreased significantly (from 48% to 9.3%) after water source switching. And there was a slightly increase in the fraction of iron-oxidizing bacteria (IOB) and siderophore-producing bacteria (SPB), but a relatively higher increase in nitrate-reducing bacteria (NRB), nitrobacteria (NOB), and iron-reducing bacteria (IRB) was observed. Taken together, these results and the corrosion morphology, indicate that pipe biofilm and corrosion were chemically and microbially stable after re-stability under water source switching. In addition, the bulk water environment showed a marked decrease in selected bacteria at genus level, including pathogenic species, indicating the improvement of quality in drinking water.

输送质量改变的水通常会导致饮用水分配系统（DWDS）的生物不稳定。但是，人们对变质水对DWDS内生物稳定性的潜在影响还知之甚少，特别是在将水转换为质量提高的水之后。这项研究的目的是研究质量改善的水对DWDS的影响，重点是生物膜的稳定性。将实用的老化管组装到管式反应器中，以模拟切换到质量提高的水的效果。当给水切换至TP 2时，管式反应器中散装水中三磷酸腺苷（ATP）的浓度从约1.2 ng / L增加到几乎超过5 ng / L。通过测量ATP浓度进行量化的生物量证实，在切换水源后，通过老化的铸铁（CI）管表面释放生物膜的风险。由于质量改善的水源而引起的水质变化可能会导致细菌在DWDS的初始阶段（前7天）释放。但是，DWDS可以在42天后建立新的稳定阶段。随着时间的流逝，分配系统的散装水中的生物量在42天后显着下降（散装中的ATP浓度保持在3 n​​g / L附近），表明水质得到改善。生物膜被与铁循环过程有关的细菌所控制，在属上，由于质量改善的水源而引起的水质变化，可能会导致细菌在DWDS初期（前7天）释放。但是，DWDS可以在42天后建立新的稳定阶段。随着时间的流逝，分配系统的散装水中的生物量在42天后显着下降（散装中的ATP浓度保持在3 n​​g / L附近），表明水质得到改善。生物膜被与铁循环过程有关的细菌所控制，在属上，由于质量改善的水源而引起的水质变化可能会导致细菌在DWDS的初始阶段（前7天）释放。但是，DWDS可以在42天后建立新的稳定阶段。随着时间的流逝，分配系统的散装水中的生物量在42天后显着下降（散装中的ATP浓度保持在3 n​​g / L附近），表明水质得到改善。生物膜被与铁循环过程有关的细菌所控制，在属上，脱硫弧菌的相对丰度最高，但是在切换水源后，脱硫弧菌的相对丰度显着降低（从48％降至9.3％）。氧化铁细菌（IOB）和产生铁载体的细菌（SPB）的比例略有增加，但是硝酸盐还原细菌（NRB），硝化细菌（NOB）和还原铁细菌的增加相对较高（IRB）。综上所述，这些结果和腐蚀形态表明，在水源切换后，管道生物膜和腐蚀在重新稳定后在化学和微生物上是稳定的。此外，散装水环境在包括病原体在内的属水平上显示出选定细菌的显着减少，表明饮用水的质量有所提高。