

E. coli, which indicates the presence of fecal matter, was detected in 58 percent of samples taken from pool filters by the U.S. Centers for Disease Control and Prevention, according to data released Thursday by the Atlanta-based agency. Pools frequented mostly by children were more likely to test positive for E. coli, which can cause stomach and respiratory illness.

Municipal pools open to all were worse than public pools requiring membership, the CDC said. Acute gastrointestinal illness related to recreational water sports has substantially increased since 1978, with diarrheal incidents and other poor swimmer hygiene being a major contributor, the CDC said.

"Finding a high percentage of E. coli-positive filters indicates 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," the agency said in a statement.

The CDC tested pool water from filters around the Atlanta area in June through August 2012. It's unlikely that swimmer hygiene differs in other areas, the CDC said.

E. coli was in 70 percent of municipal pools tested and 49 percent of pools that require membership or are at a club. The bacteria was detected in the same percentage of pools whether they were outdoor or indoor, the data show. Pools used primarily by children tested positive 73 percent of the time.


Pseudomonas aeruginosa, a bacteria that can cause rashes and ear infections, was found in 59 percent of the pools sampled, the CDC said. The contamination comes mostly from dirt, either from humans or pool toys, and underscores the need to clean pools and keep chlorine at proper levels, the CDC said.

The CDC recommended swimmers shower with soap before getting in a pool, don't swim when they have diarrhea and wash their hands with soap after using the toilet or changing diapers. Also, don't swallow pool water, the agency said.