The benefits of flushing for mitigating Legionella spp. in non-chlorinated building plumbing systems

Flushing is a common corrective action recommended by Legionella management guidelines to remove stagnant water and replenish disinfectant. Due age different local regulations, buildings may receive with low or no residual In such situations, the evidence for flushing efficacy often anecdotal, benefits are poorly quantified. Using pilot-scale premise plumbing system, flushed shower outlets were evaluated against non-flushed during simulated periods of both active demand. Water biofilm concentrations total bacteria, spp., Vermamoeba vermiformis quantified using real-time quantitative PCR. Even after all returned demand, continued have lower quantities compared several days, but decrease was little practical benefit (<0.5 log 10 [copies/L]). During prolonged however, there apparent flushing. Total bacteria grew stationary phase within 3 ± 1 while spp. took 12 6 regardless whether pipes had recently been not. hot cold effect on in pipe wall biofilms. (9.6 13.2°C) decreased 0.96 1.00 [copies/L], respectively 1.27 1.74 [copies/L] (49 60°C, respectively) difference between (1.55 both) (1.32 1.88 negligible. This suggests that flushing, even at provides added managing non-chlorinated building systems versus Finally, immediate terms reductions comparable as well rates which those populations recovered post-flush post-shower stagnation.