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

Abstract

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.

Impact of recommissioning flushing on Legionella pneumophila in a large building during the COVID-19 pandemic

“…Although fixture-flushing is expected to reduce Legionella spp. levels (Wang et al, 2012;Hozalski et al, 2020;Richard and Boyer, 2021), it can lead to momentary detrimental effects. One study also demonstrated increases in L. pneumophila levels after flushing, which was associated to building-specific features and deleterious recommissioning flushing practices such as rapid depletion of boiler temperatures with water turnover in the hot distribution system (Rhoads et al, 2022).…”

Legionella pneumophilaoccurrence in reduced-occupancy buildings in 11 cities during the COVID-19 pandemic

“…[1][2][3][4][5] While short periods of reduced water use (e.g., nights, weekends, school breaks) are common in building plumbing, many buildings were closed or at reduced occupancy for several months during the COVID-19 pandemic. [6][7][8][9][10] Reduced water use is associated with decreased disinfectant residual levels, equilibration of hot and cold water temperatures with building temperature, and potential for increased concentrations of contaminants such as disinfection byproducts, metals, and opportunistic pathogens. [11][12][13][14][15][16][17][18][19][20][21] Legionella pneumophila, the causative agent of Legionnaires' disease and Pontiac fever, was of particular concern because its occurrence is widely assumed to be associated with low water use, [22][23][24][25][26] and disease incidence is rising around the world.…”

“…33 Recent investigations into the impact of COVID-19 pandemic building closures have reported that building water quality overall was negatively impacted. 7,[44][45][46][47][48][49] However, studies have reported mixed results with respect to L. pneumophila, including no detection of L. pneumophila, 44,49 no change in occurrence as water use returned to normal levels, 45 a small increase (2x) in Legionella spp. relative abundance after two months of reduced water use, 47 and widespread detection of L. pneumophila that increased during closure.…”

Studying the impacts of non-routine extended schools' closure on heavy metal release into tap water

“…However, the target fixtures in that study did not suffer from the lead problem, and the median lead concentration in the water samples collected during stagnation was low (1.7 μg L −1 ). 29 Our recent research demonstrated that extended water stagnation within plumbing of ten large buildings at a university campus during the COVID-19 pandemic resulted in significant loss of disinfectant residuals and elevated heavy metals in tap water. 13 However, the duration of water stagnation in plumbing of those buildings was less than two months, and building recommissioning has improved the water quality effectively.…”