Pre‐ and post‐flushing of three schools in Arizona due to COVID ‐19 shutdown

A one‐day water sampling and flushing study was conducted for three schools in Maricopa County that experienced prolonged building inactivity due to the COVID‐19 pandemic: an elementary school, middle school, and high school. Grab samples were taken at hand washing sinks, water fountains, and hose bibbs before and after flushing. Samples were analyzed for free chlorine, UVA254, copper, lead, total trihalomethanes, pH, conductivity, temperature, and Legionella species. All three schools experienced an increase in free chlorine post‐flush. Copper concentrations were higher for first draw samples than post‐flush samples for all schools. Conductivity, temperature, and pH did not see a major change after flushing. UVA254 values decreased after flushing. Bromoform species saw a 20% increase after flushing at the elementary school. Legionella spp. did not decrease post‐flush at the elementary school. Overall, flushing changed the water quality at the schools. However, equipment flushing may be necessary to fully remediate Legionella spp. Article Impact Statement Prolonged closure of buildings causes water quality issues such as lack of disinfectant and Legionella. Flushing can restore water quality.