Many large buildings–schools, childcare facilities, hotels, and others–have shut their doors or reduced occupancy as the nation comes together to slow the spread of COVID-19. The Center for Disease Control and other environmental health experts are raising concerns about how this period of disuse may impact drinking water quality in these facilities. We summarize the key issues, resources, and recommendations on this topic to support building managers as they develop plans to re-open buildings to the public in the coming weeks and months. We also discussed some of these issues in a recent episode of the Buildings Podcast.

The Impact of Stagnant Water on Water Quality

Stagnant or standing water in building plumbing systems can negatively influence water quality in the following key ways:

More bacterial growth and build-up of disinfection by-products

US water systems disinfect drinking water during the treatment process through the addition of chlorine and other practices, but disinfectant residuals can be depleted as water sits in building plumbing. Those residuals prevent the growth of organisms bacteria like Legionella, which can lead to a pneumonia-like illness called Legionnaire’s disease. Longer stagnation periods may also increase the production of harmful disinfection by-products, which form as organic matter in drinking water interacts with disinfectants. 

More lead and copper may be released 

As our school and childcare facility clients know, any facility built before 2014 may have leaded plumbing products and outlets in their buildings. The most common sources of lead in large facilities are likely leaded brass, soldered lines/products, and galvanized steel. Stagnant water can compromise the protective scaling that forms on pipes and cause lead to release or dissolve more readily into drinking water. 

Equipment maintenance may have been missed 

Annual backflow preventer tests and standard maintenance of water cooling towers, boilers, and pumps are an essential part of reducing bacterial growth and pathogens in drinking water systems. 

Steps building managers can take before your community returns: 

Clean aerators/outlets & flush the system

If you have staff in the building, flushing now may help to prevent water quality from deteriorating and ultimately reduce the potential for some of the negative outcomes we have discussed. Here is a helpful resource from the Environmental Policy & Research Institute on flushing protocols. Manual flushing is not a cure-all but an advisable preventative measure in this case. Provide flushing teams with Personal Protective Equipment as some organisms can be passed through inhalation and/or dermal exposure. 

Make sure all equipment is functioning properly 

Now might be a great time to check in and perform any necessary maintenance on equipment that may be malfunctioning to ensure that everything is operating correctly. It’s especially important to check backflow preventers, pumps, cooling towers, boilers, and filtration devices.

Monitor water quality 

If your facility serves elderly populations, you may want to test for Legionella or increase monitoring for temperature and chlorine residuals if you already have a Water Management Plan in place. If your facility treats its own water, discuss the potential need for a higher dose of disinfectant. 

Steps building managers can take when your community returns: 

Continue to flush the system on a weekly basis 

Upon reopening, ongoing flushing can continue to re-stabilize protective lining on pipes and may thoroughly wash lead particulates from the plumbing system. The AWWA recommends an industry standard of about 12 weeks on flushing related to lead.

Monitor water quality 

Lead sampling is generally advisable for facilities older than 2014, especially those that serve young children, and sampling after operations resume may help guide your flushing and/or maintenance decisions. Maintain increased monitoring of chlorine residuals and temperature. Call in plumbers or water treatment advisors if you need additional guidance.

Communicate these risks & the actions you are taking to prevent poor water quality with your community 

It’s essential to establish trust with the communities your facility serves – make sure they know what steps you’ve taken to monitor and provide clean water so that they can have peace of mind as they consume your facility’s water.

Helpful Resources

• Flushing Guidance from The Environmental Policy, Science & Research Institute 
• Purdue Center for Plumbing Safety School Flushing Plans 
• CDC Guidance for Building Water Systems 
• Guidance from the National Sanitation Foundation 

Erica Walker

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Erica Walker