Rising Waters, Hidden Threats: Exploring the Unseen Risks of Basement Flooding in Pittsburgh


May 2, 2024

A flooded basement with a wet vacuum, photo by youngvet/Getty Images

Photo by youngvet/Getty Images

By Linnea Warren May, Daniel J. Bain, Alyssa Lyon, Sarah-Jane Haig, Tamara Dubowitz, Walter Lewis, Pierrce Holmes

This commentary originally appeared on Pittsburgh Post-Gazette on May 2, 2024.

Last month's record-breaking rainfall in Pittsburgh flooded roads, caused barges to float unguided under our bridges, and saw first responders rescuing citizens from their houses by boat. There's a hidden cost to this flooding, one that harms the structural integrity of many Pittsburgh homes and the health of many Pittsburghers.

While our riverfronts—particularly riverfront parks, trails, and parking lots—are, to some degree, “designed to flood,” and can hold water for extended periods without causing significant damage, our basements are very much not.

How Basements Flood

We know from work done in other cities that flooding harms houses and health, but we don't know how much it affects Pittsburgh's historically disinvested neighborhoods. Finding out is a goal of a research-community partnership, Health and High Water, which is currently studying the problem in Homewood and the Hill District. The partnership includes the nonprofit research organization RAND, Homewood Children's Village, the University of Pittsburgh, and the Black Environmental Collective.

Even weeks after the sudden downpours, residents may be wielding shop vacs, continuously running dehumidifiers, or dealing with breathing problems and headaches due to damp or wet conditions in their basements.

Water can enter basements all kinds of ways: through cracks in the foundation or overflowing sewer backups, via poorly designed or clogged drainage systems, or simply from surface runoff during especially heavy rainfall. These closed-off and poorly ventilated spaces can retain moisture for weeks to months after a flood.

Big storms increase the risk of combined sewer systems becoming overwhelmed, leading to basement sewer backups and flooding.

Share on Twitter

Pittsburgh is not the only urban area experiencing more frequent and intense storms, just as it is not the only city with a combined sewer system—one that collects both rain and wastewater in a single set of pipes—facing increasing strain. Big storms increase the risk of combined sewer systems becoming overwhelmed, leading to basement sewer backups and flooding.

Often dismissed as “nuisance flooding,” recurrent basement flooding is much more than a nuisance. It costs homeowners, many financially vulnerable, a lot to clean up and poses significant threats to public health and safety.

Long-Term Effects

Recurrent flooding not only damages property stored in basements, but lingering moisture affects a building's structural integrity and creates an ideal environment for mold growth and radon-gas infiltration, both known health hazards.

A 2021 study of homes in Detroit showed that homes that experienced recurrent flooding were 50 percent more likely to experience visible mold growth in basements than those that didn't. In the homes that flooded, people were 42 percent more likely to experience breathing problems like asthma.

Similar research has not been done in Pittsburgh. However, anecdotal evidence and recent reporting suggest that recurring residential flooding is also a problem here. Our communities have long struggled with higher rates of asthma than the national average, due to legacy industry and regulatory inefficiencies that create poor regional air quality. And basement mold from flooding might also be to blame.

Due to failing sewer systems and their locations, some of Pittsburgh's most historically disinvested neighborhoods—including Homewood and Larimer in the Negley Run Watershed—have experienced significant street flooding in the past 15 years. This includes a particularly dramatic incident of flooding on Washington Boulevard in 2011 that led to four deaths.

Those problems combined with aging housing stock make these neighborhoods more likely to have wet basements. That of course exacerbates household health challenges.

Property owners can take steps to prevent or at least mitigate flooding in basements, including ensuring proper grading around foundations, installing sump pumps, maintaining gutters and downspouts, and sealing cracks in the foundation walls. But these are expensive solutions, and there is a lack of guidance from local agencies around helping residents understand how to take these steps, and why they should.

Worse still, roughly half of Pittsburgh residents are renters who cannot implement such flood-mitigation measures where they live.

Some of Pittsburgh's most historically disinvested neighborhoods have experienced significant street flooding in the past 15 years.

Share on Twitter

Floods and Health

However, the City of Pittsburgh, the Pittsburgh Water and Sewer Authority, the Urban Redevelopment Authority, and community-based organizations have implemented neighborhood-level flood prevention efforts. These include green infrastructure solutions such as rain gardens, permeable pavement, and bioswales to collect and manage stormwater where it falls and reduce the risk of basement flooding. (Bioswales are ditches filled with vegetation that collect, filter, and move stormwater.)

But that's just not enough to address the scale of the problem. It is time to stop thinking about wet basements as simply a nuisance, and understand the role of flooded basements in some of the critical health issues facing our community.

Linnea Warren May is an associate policy researcher at RAND. Daniel J. Bain is an associate professor of geology and environmental science at the University of Pittsburgh. Alyssa Lyon is director of the Black Environmental Collective, part of UrbanKind Institute. Sarah-Jane Haig is an assistant professor of civil and environmental engineering and environmental and occupational health at the University of Pittsburgh. Tamara Dubowitz is a professor and chair of the Department of Epidemiology at the University of Pittsburgh School of Public Health and an adjunct policy researcher at RAND. Walter Lewis is president and CEO of Homewood Children's Village. Pierrce Holmes is a policy analyst at RAND. The authors are members of a multi-institution research-community partnership called Health and High Water.

More About This Commentary

Commentary gives RAND researchers a platform to convey insights based on their professional expertise and often on their peer-reviewed research and analysis.