Swimming Pools Prone to Fecal Contamination
A new report by the Centers for Disease Control and Prevention has found that public pools contain unacceptable levels of human fecal contamination, which potentially could cause disease.
Researchers sampled the backwash from pool filters, where bacteria typically accumulate, and are present in greater numbers than in the water alone. From June to August last year, 161 filter samples were collected at metro Atlanta area public pools and tested.
Both indoor and outdoor pools were tested. All but one of the filters were rapid sand filters, which are commonly used in public pools.
The CDC examined the samples for the genetic material (such as DNA) of many types of germs. Results showed that 58 percent of the samples contained E. coli, bacteria which are normally found in the human intestinal tract and feces. When E. coli shows up in a test of pool filters, it is a sign there is fecal contamination.
E. Coli Means ‘Fecal Incident’ Occurred
When a high percentage of E. coli is found in the filters, it indicates that swimmers are having a “fecal incident” in the water, or that feces enters the water from their bodies because they do not take a shower before entering the pool, according to CDC.
None of the samples contained a type of E. coli called “O157:H7,” which produces a toxin when ingested and can cause serious illness.
Another bacteria called “Pseudomonas aeruginosa,” which can cause skin rashes and ear infections, was found in 59 percent of samples. Finding this particular bacteria indicates it was shed in the water by swimmers, although Pseudomonas is also found in dirt and could have come from objects in the water such as kickboards.
Both Pseudomonas and E. coli were detected in 42 percent of samples.
Other Bacteria Found as Well
Two other germs, Cryptosporidium and Giardia, which are spread through feces and cause diarrhea, were found in less than 2 percent of samples.
More bacteria were found in filters used in outdoor instead of indoor pools, possibly because sunlight breaks down chemicals used to treat water, and the water is warmer, which breeds bacteria.
The tests the researchers used only showed if the germs were there — not if they were alive or could cause actual infections.
The study did not include water parks, residential pools, or other types of recreational water.
Based on the results, Michele Hlavsa, chief of CDC’s Healthy Swimming Program, advises pool users to: “be aware of how to prevent infections while swimming.”
“Remember, chlorine and other disinfectants don’t kill germs instantly,” she adds. “That’s why it’s important for swimmers to protect themselves by not swallowing the water they swim in and to protect others by keeping feces and germs out of the pool by taking a pre-swim shower and not swimming when ill with diarrhea.”
The CDC recommends the following to swimmers to prevent infections:
- Do not swim when you have diarrhea (anti-diarrhea products here),
- 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,
- Do not swallow the water you swim in
Maintain the pool properly:
- Check the chlorine level and pH before getting into the water.
- Maintain proper chlorine levels (1-3 mg/L or parts per million [ppm] and pH (7.2-7.8) to maximize germ-killing power (pool test strips are widely available in stores).
Regarding young children, take them on bathroom breaks every 60 minutes or check diapers every 30-60 minutes. Also, change diapers in the bathroom or diaper-changing area and not at the poolside, because germs can rinse into the pool water.
For more information visit CDC’s healthy swimming/recreational water page.