During normal operation treatment plants remove waste and grit from water. Chlorination kills bacteria before treated water gets discharged into rivers, creeks or estuaries.

But major storms and hurricanes can send huge volumes of water into these plants forcing discharge of untreated or only partially treated water. Stormwater can also infiltrate the ground and enter deteriorated or poorly constructed pipes called laterals that connect homeowners’ pipes to sewer systems. That’s what happened to Lilly Hawkins of Wilmington, N.C.

Last year, her downstairs bathroom flooded after she drained her upstairs tub. A plumber told her that wastewater in the pipes had regurgitated into her bathroom because the lateral in the sewer had a clog. Hawkins and her family tried to clean it themselves.

“We wore dishwashing gloves and rain boots,” she said. “I didn’t feel clean for a solid two weeks.”

Eventually, Hawkins’ mother called professionals who arrived in hazmat suits to take care of the problem.

Dire consequences of contaminated water

 Rachel Noble, a professor of marine science at the University of North Carolina at Chapel Hill, said contaminated water can have dire consequences.

“The water is going to flow through the treatment plant far too fast, and it’s actually not getting treated properly,” she said. “What actually is happening is that you have [water] coming out that’s not fully treated.”

Untreated water contains bacteria from people’s fecal matter that is harmful to human health. Besides drinking contaminated water, people can encounter untreated water by swimming in contaminated lakes, streams or estuaries.

A 2020 study published in Science of the Total Environment analyzed water quality before and after flooding in Beaufort, N.C. The researchers sampled water from two locations that discharged into Taylor’s Creek, home to two recreational areas.

The researchers found “compelling evidence” that much of the fecal bacteria found in the water after flooding came from human waste. They concluded that there was a statistically significant correlation between storm conditions and fecal bacteria discharge, meaning the fecal matter’s presence was likely a result of flooding.

Lack of notification of contaminates

Emily Sutton works for the Haw River Assembly, a public interest group that monitors the Haw River as it passes through more than 100 miles of the North Carolina Piedmont before discharging into Jordan Lake. Sutton said governments need to notify communities about contaminates released into the river.

“Once it’s in the [water], you can’t clean it out,” she said. “That’s a huge risk for human health, and people aren’t getting those notifications.”

Contaminated water can also enter the human food chain through the consumption of shellfish and other organisms. North Carolina prohibits people from harvesting shellfish from areas near water treatment plants, but UNC marine scientist Noble said flooding increases the threat of dangerous discharges.

“When [contaminated water] comes out into the estuary, it’s going to move,” she said. “And so what happens is that that material can be transported and can get into the food chain by getting into oysters and clams.”

In a 2010 study published in Water Research, researchers sampled storm water from the New River Estuary in Onslow County, N.C., to look for fecal bacteria. They found that water flowing downstream to shellfishing areas exceeded the state standard for fecal bacteria by more than 4.5 times.

Human feces are more dangerous to human health than animal feces because exposure can transmit highly host-specific viruses, according to a 2007 study published in Water Research. Viruses and bacteria in the water can cause gastrointestinal infections leading to diarrhea, nausea and vomiting. Noble said fecal contamination carries other risks including heart and upper-respiratory problems. Bacterial infections, such as salmonella and E.coli, can also cause vomiting and diarrhea.

Scientists say that climate change is leading to more intense storms and worsening flooding on the North Carolina coast. Noble said governments can pursue solutions, such as pumping out groundwater and capturing stormwater on a large scale to prevent water overflow from treatment plants. Governments may also close recreational waters and restrict the sale of shellfish after a sewage overflow.

As climate change worsens flooding in North Carolina, wastewater treatment plants lose the capacity to clean our water. Those on the coast like Lily Hawkins can take precautions to protect their health when treatment plants don’st have the capacity to do so.