CDC Study Finds E. Coli in Public Swimming Pools

A study of public swimming pools performed during last summer’s swim season found that feces are frequently introduced into pool water by swimmers. 

Through the study, released last week by the Centers for Disease Control and Prevention, researchers found 58 percent of the pool filter water samples collected in public pools tested positive for E. coli, bacteria normally found in human feces. The E. coli is a marker for fecal contamination, the CDC said.

The CDC reports that a high percentage of E. coli-positive filters indicates that swimmers frequently contaminate pool water when they have a fecal incident in the water or when feces rinse off of their bodies because they do not shower thoroughly before getting into the water.

“People, when they swim, obviously their whole body goes in the water, so anything that is on their bodies is likely to end up in the water,” Dr. Ronald Voorhees, the acting director of the Allegheny County Health Department, told KDKA-TV.

Of the samples, Pseudomonas aeruginosa, which can cause skin rashes and ear infections, was detected in 59 percent of samples. Finding Pseudomonas aeruginosa in the water indicates natural environmental contamination or contamination introduced by swimmers.  

Germs that are spread through feces and cause diarrhea, Cryptosporidium and Giardia, were found in less than 2 percent of samples.

Indoor and outdoor public pools in Atlanta were sampled. None of the samples tested positive for E. coli O157:H7, a toxin-producing E. coli strain that causes illness, according to the CDC.

The study did not address water parks, residential pools or other types of recreational water.

However, the report said it is unlikely that swimmer-introduced contamination, or swimmer hygiene practices, differ between pools in the study and those in the rest of the country.

Chlorine, the primary pool disinfectant, should handle most microbes. But some E.coli, which can cause serious gastrointestinal illness, can be stubborn if chlorine levels are not adequate.

“So anybody that’s had diarrhea recently, until they are over it, they should not use a pool,” Dr. Voorhees told KDKA.

The study was presented in recognition of Recreational Water Illness and Injury Prevention Week, which runs May 20 to May 26. The goal of prevention week is to raise awareness about healthy swimming, including ways to prevent recreational water illnesses (RWIs). 

CDC recommends that all swimmers take the following steps to prevent infections while swimming:

CDC recommends that parents of young children also take the following steps:

• Keep feces and other contaminants out of the water.
  • Do not swim when you have diarrhea.
  • Shower with soap before you start swimming.
    • Take a rinse shower before you get back into the water.
  • Take bathroom breaks every 60 minutes.
  • Wash your hands with soap after using the toilet or changing diapers.
• Check the chlorine level and pH before getting into the water.
  • Pools: Proper chlorine (1–3 mg/L or parts per million [ppm]) and pH (7.2–7.8) levels maximize germ-killing power.
  • Most superstores, hardware stores, and pool-supply stores sell pool test strips.
• Do not swallow the water you swim in.

CDC recommends that parents of young children also take the following steps:

• Take children on bathroom breaks every 60 minutes or check diapers every 30–60 minutes.
  • Change diapers in the bathroom or diaper-changing area and not at poolside where germs can rinse into the water.