Drinking water reservoir dynamics: exploring the interface between design and microbial ecology

ABSTRACT The biological stability of treated drinking water within distribution networks is crucial for maintaining microbial quality and ensuring water safety. Although various management strategies exist, the effect of distribution system design and operation, particularly service reservoirs, on microbial quality remains understudied. This study examined the impact of service reservoir design and operation on microbial community composition using 16S V4 amplicon sequencing. Results indicated that microbial communities showed spatially consistent community structure within individual months, despite detectable turnover in low-abundance taxa, suggesting that reservoir design, internal flow patterns, and fill cycles did not significantly influence microbial composition. In contrast, significant month-to-month variation was detected, likely due to seasonal changes in source water quality or treatment processes. Temperature mapping identified potential stagnation zones, but they did not correspond to distinct microbial shifts. A core microbiome of 96 ASVs persisted across all sampling months, comprising approximately 43.5% of total reads. These findings underscore the importance of well-designed and effectively managed reservoirs in maintaining stable conditions that support drinking water biostability, thereby safeguarding public health.