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Study examines ‘extreme water stagnation’ in buildings shuttered by pandemic


Researchers at Indiana’s Purdue University have begun a field study to determine how water quality could change in shuttered buildings like schools, sports venues and government offices during the COVID-19 pandemic.

The concern is that water left sitting for long periods of time could contain excessive amounts of heavy metals and pathogens concentrated in pipes. It’s a fear, researchers say, that may be of even greater concern when previously defunct hospital facilities are reopened to meet the growing need of care in the U.S. According to the Centres for Disease Control and Prevention, COVID-19 cases stood at over 828,000 as of April 22, 2020.

“We don’t design buildings to be shut down for months,” said Andrew Whelton, a Purdue associate professor of civil engineering and environmental and ecological engineering, in a press statement. “This study focuses on the consequences and could help building owners make sure that their buildings are safe and operational when occupants return,” he added.

The study, funded by the National Science Foundation’s Rapid Response Research (RAPID) program, states that a team will firstly characterize disinfectant, heavy metal, and bacterial changes during extended building closures, and then second, develop evidence-based plumbing remediation methods to address water quality deterioration.

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Once completed, the study results will help guide building owners and water utilities on how to safely recommission buildings that had low or no occupancy during the pandemic.

Whelton and other researchers across the U.S. have begun drafting recommendations around extended water stagnation in a paper pending publication. Collaborating with Purdue in the effort are experts from leading plumbing safety scientists and engineers from Virginia Tech, Legionella Risk Management Inc., Arizona State University, the University of Memphis, the University of Iowa, Northeastern University, and Polytechnique Montréal in Canada.

While there is still much to learn about stagnation, researchers say that previous closure events, prior to the pandemic, have been associated with outbreaks such as Legionnaires disease.

Whelton’s team has previously conducted studies on school buildings shut down for the summer, finding that water quality changes over time. In 2019, his team was called into California after the Camp Fire and advised health officials and the community on returning their buildings to safe use.

“With normal building use throughout a district, even small amounts of water use would help draw disinfectant residual into a building. In the COVID-19 era, many low-use buildings in one area could affect the disinfectant residual in the water mains,” said Caitlin Proctor, a Lillian Gilbreth Postdoctoral Fellow at Purdue, in a statement. “As we come back to work after social distancing, even complete building flushing might not be successful in drawing in fresh water,” she added.

For this field study, Whelton’s team is collecting samples at sinks and water fountains in three buildings – tracking temperature, oxygen, heavy metals such as lead and copper, and how microbial communities in pipes change over time.

“When you use water, you’re bringing in chlorine, nitrogen, phosphorus and a small amount of carbon,” said Proctor. “Bacteria sitting on the walls of pipes store up those nutrients for later use. But with months-long stagnation, there isn’t going to be any oxygen, new nitrogen or phosphorus,” she added. “So the bacteria that can compete under normal delivery of nutrients might not be able to compete anymore. For example, bacteria that do really well when there’s no oxygen might outcompete those that need oxygen.”

Whelton’s team is also tracking Legionella pneumophila, known to cause a bacterial form of pneumonia. Some hospital buildings already have plans in place to flush out stagnant water that could carry this pathogen, but more studies on stagnant water could inform how frequently and how long they should flush.

In addition to observing water left sitting still in buildings, the team will study how stagnation affects water softeners and water heaters. In the lab, the researchers will let the water sit still for long periods of time, watching for chemical and microbiological changes.


  1. Would appreciate a study on health risks with stagnant water puddles in buildings due to leaks through cracks in concrete or brick foundations, especially in boiler rooms or elevator pits.


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