Waegenaar F, Pluym T, Vermeulen E, De Gusseme B, Boon N. 2025. Appl Environ Microbiol 91:e00686-25.
Highlights:
- This study used a pilot-scale drinking water distribution system with three identical polyvinyl chloride(PVC) loops to assess the impact of flushing with and without chlorination.
- Loop 1 was flushed with tap water and sodium hypochlorite, followed by two non-chlorinated flushes
- Loop 2 was unflushed
- Loop 3 underwent three flushes
- The water had a 7-day residence time.
- Results showed that chlorinated flushing promoted microbial regrowth for all loops.
- Biofilm cell densities remained stable across conditions.
- Bacterial indicators declined over time, with decay rates highest in chlorinated loops, likely due to increased microbial competition.
- This study provides critical insights into how traditional flushing, both with and without chlorination, influences microbial regrowth.
- Findings reveal that chlorinated flushing promotes the regrowth of resident drinking water bacteria while accelerating the decay of introduced unwanted bacterial indicators, emphasizing the complex trade-off between microbial control and system stability.
- Understanding these dynamics is essential for optimizing flushing procedures, minimizing unintended consequences, and improving distribution system resilience.
