Drinking Water Quality as a Function of Stagnation in Controlled Pilot-Scale Systems

This study examines the impact of varying stagnation regimes - daily, weekly, biweekly, and monthly - on the chemical and microbial dynamics in controlled, large-scale plumbing systems designed to reflect real-world conditions. The findings reveal that biweekly and monthly stagnation often had similar results and that weekly stagnation, based on weekly flushing protocols, was insufficient to prevent the growth of bacteria such as sulfate-reducing bacteria (SRBs) and drinking water pathogens, specifically Mycobacterium spp. These results highlight concerns about the effectiveness of current water management practices during low occupancy. Extended stagnation was associated with increased scale formation and particulate settling in tanks with increased concentrations of particulate iron in copper pipes. While daily use controlled microbial growth, elevated copper levels were exhibited in the pipes potentially attributed to a lack of scale formation in the newly constructed plumbing system. These results underscore the need for revised water management strategies to ensure safe drinking water, particularly in light of the public health risks posed by inadequate flushing protocols during building closures or low occupancy periods.