The coronavirus pandemic has shuttered many buildings. As prospects for reopening rise, so too does the need to contend with water systems potentially contaminated during the shutdown.
Stagnant water in pipes or tanks can breed microorganisms like Legionella pneumophila, the bacteria that causes Legionnaires' disease.
Heavy metals like lead and copper also can build up, as can byproducts of chlorination by water utilities.
Kerry Hamilton of Arizona State University's Biodesign Center for Environmental Health Engineering says reopening will require the thorough flushing and maintenance of affected systems, and a good water management plan.
"It's not something where you're just going to open the faucet one time and walk away, and it's solved forever. It's something that we manage over time," Hamilton said.
Hamilton and her team assess the risks of different disease-causing microorganisms in the environment by testing water at taps and showers, especially those connected to hot water lines.
Legionnaires' bacteria thrives in warmer water.
"We're trying to see if there were changes in pathogens before, during or after this COVID-19 shutdown period and trying to see what we can do to prevent people from becoming sick and exposed to these organisms," she said.
Her group is currently surveying a LEED certified building in Arizona. Buildings that meet the Leadership in Energy and Environmental Design sustainability standards prioritize water efficiency, sometimes at a cost.
"That lower water use can also lead to stagnation or increase water age in the pipes, which can then result in increased microbial growth," said Hamilton.
The variety of plumbing materials and layouts in buildings from different eras and locations impede attempts to generalize policies and procedures. But Hamilton says most buildings will benefit from flushing old water through fixtures, cleaning shower heads and faucet aerators, and flushing and servicing water tanks.
Homeowners reopening houses should also replace water filters, clean humidifiers and ice machines, and ensure hot tubs do not have a scale growing on them. Hamilton says they might also consider raising the temperature in their water heaters to 140 degrees Fahrenheit.
Her review of the subject appears in American Water Works Association journal Water Science.