No Poo in the Pool! Tips for Safe Enjoyment of the Water

First published August 2016
Updated August 2026

Nothing says summer like a day at the pool, waterpark, lake, or beach. Swimming is a great way to stay active and cool off, but even the cleanest-looking water can contain germs that make people sick. Fortunately, preventing most recreational water illnesses is simple.

One of the most common causes of diarrhea linked to swimming is Cryptosporidium, or Crypto. This microscopic parasite spreads when people accidentally swallow contaminated water. Crypto is the leading cause of outbreaks associated with treated recreational water in the United States. Unlike most germs, it is highly resistant to chlorine and can survive in a properly maintained swimming pool for more than seven days. That's why even clean, well-maintained pools can become contaminated if someone with diarrhea gets into the water.

Keep the Water Clean

Most pool contamination comes from tiny amounts of fecal matter (poop) left on swimmers' bodies. Even microscopic amounts can contain millions of germs.

Help protect everyone by following these simple steps:

• Shower with soap before swimming.
• Don't swallow pool or lake water.
• Take young children on bathroom breaks every hour.
• Check swim diapers every 30–60 minutes and change them in a restroom—not poolside
• Wash hands thoroughly after using the bathroom or changing diapers.

Chlorine Helps—But It Isn't Instant

Chlorine kills many germs quickly, but not all of them. This is why keeping sick swimmers out of the water is the best way to prevent outbreaks.

Sick? Sit It Out

If you or your child has diarrhea, don't swim. This single step is one of the most effective ways to protect other swimmers.

If your child is diagnosed with Cryptosporidium, the Centers for Disease Control and Prevention (CDC) recommends staying out of pools, splash pads, waterparks, lakes, and other recreational water for at least two weeks after diarrhea has completely stopped, because the parasite can continue to be shed even after symptoms improve.

Lakes and Waterparks Have Their Own Risks

Pools aren't the only places where germs spread. Waterparks often have multiple attractions connected by shared filtration systems, allowing germs to circulate quickly. Lakes, rivers, and streams are not disinfected and can become contaminated with sewage or animal waste, especially after heavy rainfall. Before swimming in natural water, check for local health advisories or beach closures.

Different Germs, Similar Symptoms

Many bacteria, viruses, and parasites acquired from recreational water cause similar symptoms, including diarrhea, stomach cramps, vomiting, and fever. Because treatment differs depending on the cause, rapid diagnosis is important, particularly for young children who can become dehydrated quickly.

At Nationwide Children's Hospital, physicians can order a highly specialized molecular test that detects 20 of the most common gastrointestinal pathogens, including Cryptosporidium, from a single stool sample. Once the specimen reaches the laboratory, results are typically available in about two hours, helping doctors identify the cause of illness and begin the most appropriate treatment as quickly as possible.

When Should You Call Your Doctor?

 If your child has worsening or bloody diarrhea, a fever higher than 101˚F, or vomiting that doesn’t improve within 24 hours – and you’ve been in a public water space within the last few days – it’s time to go to the doctor or urgent care.