Abstract
Managing building water systems is complicated by the need to maintain hot water temperatures high enough to control the growth of Legionella spp. while minimizing the risk of scalding. This study assessed water quality management practices in large buildings in the United States. Surveys conducted with building water quality managers found that more than 85% of buildings have hot water temperatures that are consistent with scald risk mitigation guidelines (i.e., <122 °F/50 °C). However, nearly two thirds and three quarters of buildings do not comply with the common temperature guidance for opportunistic pathogen control, i.e., water heater setpoint > 140 °F (60 °C) and recirculation loop > 122 °F (50 °C), respectively; median values for both setpoint and recirculation loop temperatures are 10 °F (6 °C) or more below temperatures recommended for opportunistic pathogen control. These observations suggest that many buildings are prone to Legionella spp. risk. The study also found that 27% of buildings do not comply with guidelines for time to equilibrium hot water temperature, over 33% fail to monitor temperature in the recirculation loop, more than 70% fail to replace or disinfect showerheads, more than 40% lack a written management plan, and only a minority conduct any monitoring of residual disinfectant levels or microbiological quality. Given the rise in Legionellosis infections in recent years, coupled with highlighted water quality concerns because of prolonged water stagnation in plumbing, such as in buildings closed due to COVID-19, current management practices, which appear to be focused on scald risk, may need to be broadened to include greater attention to control of opportunistic pathogens. To accomplish this, there is a need for formal training and resources for facility managers.
Highlights
We focus on existing water quality management practices in the United States through semi-structured and structured surveys of those managing building water systems
Many participants (88%) were responsible either only for operations or both the design and operations of the building plumbing systems, while only 7% of the participants were responsible for design but not operations
The results show that greater than 80% of the buildings were monitored for water heater setpoint temperature, temperature at faucet, and time to tap
Summary
Building plumbing systems often have the appropriate temperature, moisture, and nutrient conditions conducive to the growth of opportunistic premise plumbing pathogens (OPPPs), Legionella spp. OPPPs cause significant human health risks, for the elderly and immunocompromised [2]. Disease, caused by premise plumbing pathogens in the genus Legionella spp., accounts for approximately 2–15% of cases of community-acquired pneumonia worldwide [3]. In the United States, the Legionnaires’ disease cases have increased 5.5-fold in recent years, from 0.42 per 100,000 population in 2000 to 2.29 per 100,000 population in 2017, and the number of outbreaks nearly quadrupled during the period from 2009 to 2017 [4]. A more glaring example of building plumbing system failure is the public health crisis in
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