Reviewed by Brunilda Nazario, MD on July 17, 2019
From the WebMD Archives

July 17, 2019 -- When you go to the beach, you probably worry about things like sunburn or drowning. But there’s something else to consider: bacteria in the water.

Recent cases of flesh-eating bacterial infections have made headlines, yet you’re far more likely to wind up with nausea, diarrhea, or a respiratory infection after a trip to the beach. Researchers estimate bacteria in the waterways cause more than 90 million cases of stomach, respiratory, ear, eye, and skin-related illnesses every year in the U.S., while fewer than 1,500 cases of necrotizing fasciitis (aka flesh-eating bacteria) happen here annually, from any cause.

“Fecal matter, like from sewage discharge, is responsible for a lot of the pollution,” says Mark Mattson, president of Swim Drink Fish, an organization that promotes safe water. “After it rains, urban beaches are often contaminated from the runoff. And in rural areas, it’s agricultural pollution.”

So how can you know if it’s safe to swim? Across the United States, local, state, territorial, and tribal health agencies monitor the water quality at coastal and Great Lakes beaches. They all do their own testing, and not every beach is tested daily. Typically, testing checks for E. coli bacteria in freshwater and enterococcus bacteria -- which indicate fecal contamination -- in ocean water. If levels go beyond a federally established limit, the beach should be closed to swimming.

There is no national requirement to post signs on beaches when the water is contaminated. Those notices are handled at the state and local levels. But to find out if your favorite beach is safe, you don’t necessarily have to track down the local testing organization. Instead, you can find it all in one place:

  • The Environmental Protection Agency offers a clickable map of U.S. beaches -- you can see which beaches are monitored and if they’re open for swimming. Be aware: Because this database relies on individual agencies reporting the status, it may not be up to date.
  • The Swim Guide, a website and free app run by Swim Drink Fish, collects real-time data from affiliates monitoring thousands of swimming spots around the world. You can drill down to see how recently the water was tested and how it’s been rated historically.

If you don’t have access to that information ahead of time, watch for clues when you’re at the beach:

  • Are there a lot of people in the water? “That’s usually a sign of a community that honors and respects clean water,” Mattson says. On the other hand, if you don’t see anyone in the water, that’s a good sign to stay out of it.
  • Do you see discharge pipes? Pollutants may be flushed into the water nearby.
  • Did it rain recently? Urban beaches will be prone to pollution.

Even if the beach is open for swimming, you can help protect your health:

  • Always wash your hands with soap and water before eating -- even if you’ve just been digging in the sand. It can be contaminated, too.
  • Try not to swallow the water you’re swimming in.
  • Got an open wound? Don’t go in the water at all.
  • And once you get home, wash your whole body.

Mattson says if you have no symptoms, you don’t need to worry. But if you’re not feeling well or are generally weak after swimming in water that might be contaminated, get yourself to a doctor -- don’t wait for alarming symptoms to emerge. While rare, necrotizing fasciitis can be fatal or have other serious effects on your health if an infection is not treated with antibiotics right away, according to the CDC.

The good news, according to Mattson: “Bacteria doesn’t live long in the water. So when you have a problem, it’s because there’s been recent discharge. If we can keep those pollutants out of the water, there should be no problem for future swimming.”

Show Sources

Fox43: “Woman infected with flesh-eating bacteria at Virginia beach.”

CNN: “Flesh-eating bacteria kills a Memphis man who visited Florida waterways.”

Environmental Health: “Estimate of incidence and cost of recreational waterborne illness on United States surface waters.”

CDC: “Vibrio vulnificus Infections and Disasters,” “Necrotizing Fasciitis: All You Need to Know.”

Environmental Protection Agency: “2012 Recreational Water Quality Criteria,” “LEARN: What Affects Human Health at the Beach.”

Woods Hole Oceanographic Institution: “Beach Closures.”

CDC: “Necrotizing Fasciitis: All You Need to Know.”

© 2019 WebMD, LLC. All rights reserved. View privacy policy and trust info