Pool Water Can Make You Sick: What’s Lurking?

Summer swims risk exposure to persistent parasites and bacteria.

That refreshing dip in the public pool this summer could expose you to more than just sunshine. While chlorine is standard, it doesn’t kill germs instantly, leaving some to thrive for extended periods and potentially cause illness.

The Hidden Contaminants

Every swimmer introduces a cocktail of bodily fluids into the water. The Centers for Disease Control and Prevention (CDC) reports that a single swimmer can leave behind millions of microbes from spit, vast amounts of bacteria from feces, sweat, and urine. These substances react with chlorine to form chloramines, which cause eye irritation and the characteristic pool odor.

Chlorine’s Limits and Stubborn Germs

While effective against some bacteria like E. coli, chlorine’s ability to neutralize other contaminants is limited. Hepatitis A, for instance, can persist in treated water for up to 16 minutes after fecal contamination. Giardia, a parasite spread through accidental defecation or improper rinsing, may require 45 minutes or longer to be eliminated and can cause significant digestive distress.

The “Super Pooper” Parasite

The most concerning culprit is cryptosporidium, a parasite encased in a hardy shell that allows it to survive in chlorinated water for up to ten days. Swallowing even a small amount of water contaminated with this parasite can lead to weeks of debilitating watery diarrhea, cramps, nausea, and vomiting. Between 2009 and 2017, cryptosporidium outbreaks linked to treated pools increased annually, sickening thousands across the United States.

Beyond Parasites: Bacteria, Viruses, and Fungi

Other pathogens like Shigella, norovirus, and adenovirus can also contaminate pool water. Bacterial threats include Legionella, which can cause severe pneumonia, and Pseudomonas, responsible for skin rashes and ear infections. Fungal spores, thriving in damp pool environments like decks and locker rooms, contribute to conditions such as athlete’s foot.

Protecting Yourself: Simple Steps for Safer Swimming

Preventing illness is possible with simple precautions. The CDC advises staying out of the water if experiencing diarrhea and waiting two weeks after symptoms cease. Showering for at least one minute before entering the pool helps remove dirt and germs. Parents should ensure frequent bathroom breaks for children and never change diapers poolside. Avoiding swallowing pool water and thoroughly drying ears after swimming can also mitigate risks.

Public pools face significant challenges with hygiene. In New York City alone last year, hundreds of pool closures occurred due to fecal contamination. A recent national survey revealed that over half of adults admitted to urinating in pools. These practices underscore the importance of individual responsibility in maintaining pool safety.