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Diarrheal Illness

Diarrhea and swimming don’t mix! Diarrhea is the most common recreational water illness (RWI). Swimmers who are sick with diarrhea—or who have been sick in the last two weeks—risk contaminating pool water with germs.

Diarrheal illnesses are caused by germs such as Crypto (short for Cryptosporidium), Giardia, Shigella, norovirus and E. coli O157:H7. These germs can live from minutes to days in pools, even if the pool is well-maintained. Some germs are very tolerant to chlorine and were not known to cause human disease until recently. Once the pool has been contaminated, all it takes is for someone to swallow a small amount of pool water to become infected.

Crypto has become the leading cause of swimming pool-related outbreaks of diarrheal illness. It can stay alive for days even in well-maintained pools and can cause prolonged diarrhea (for 2-3 weeks). For more information about Crypto and healthy swimming, see the fact sheet below and visit CDC’s Crypto website.

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	Crypto Fact Sheet

Facts About Crypto and Swimming Pools

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Giardia is another germ that often causes swimming pool-related outbreaks of diarrheal illness. It has a tough outer shell that allows it to survive for up to 45 minutes even in properly chlorinated pools. For more information about Giardia and healthy swimming, see the fact sheet below and visit CDC’s Giardia website.

Print-and-Go Fact Sheet

	Giardia fact sheet

Facts About Giardia and Swimming Pools

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How is diarrhea spread at recreational water venues?

Infectious diarrhea can contain anywhere from hundreds of millions to one billion germs per bowel movement. Swallowing even a small amount of water that has been contaminated with these germs can make you sick. Tiny amounts of fecal matter are rinsed off all swimmers' bottoms as they swim through the water. That is why it is so important to stay out of the pool if you are sick with diarrhea, shower before swimming, and avoid swallowing pool water.

At public swimming facilities, continuous filtration and disinfection of water should reduce the risk of spreading germs. However, swimmers may still be exposed to germs during the time it takes for chlorine to kill germs (certain germs take longer to kill than others) or for water to be recycled through filters. Many pool facilities use one filtration system for several pools. This causes water from various pools to mix and potentially spreads germs throughout connected pools in a very short amount of time. This means that a single diarrheal incident from one person could contaminate water throughout a large pool system or waterpark.

What should I do if I have diarrhea?

To help protect the health of others, do not swim when you have diarrhea. Microscopic amounts of infected fecal matter can contaminate an entire pool or hot tub and make others sick if they swallow the water.

If you have diarrhea, the most important thing you can do is to drink plenty of fluids to prevent dehydration. This is especially important for young children, pregnant women, and persons with weakened immune systems (such as those living with HIV/AIDS, those who have received an organ transplant, or those receiving certain types of chemotherapy).

Seek medical care immediately if you experience any of the following symptoms:

  • your diarrhea is bloody
  • your diarrhea does not resolve in 5 days
  • your diarrhea is accompanied by fever or chills
  • you are dehydrated (Signs of dehydration include: dry or "cottony" mouth, cracked lips, dry flushed skin, headache, irritability, not urinating at least four times a day, no tears when crying, not sweating, or confusion)

A health care provider may prescribe medicine to help replace the fluids your body has lost because of the diarrhea. In some cases, over-the-counter medications can slow the diarrhea.

How do I protect myself and my family?

Take action! We all share the water we swim in, so each of us plays an essential role in helping to protect ourselves, our families, and our friends from germs that can cause RWIs.

All swimmers should take the following easy and effective healthy swimming steps:

Keep the pee, poop, sweat, and dirt out of the water!

  • Stay out of the water if you have diarrhea.
  • Shower before you get in the water.
  • Don’t pee or poop in the water.
  • Don’t swallow the water.

Every hour—everyone out!

  • Take kids on bathroom breaks.
  • Check diapers, and change them in a bathroom or diaper-changing area–not poolside–to keep germs away from the pool.
  • Reapply sunscreen.
  • Drink plenty of fluids.

For more information on how to protect yourself and your family from RWIs, follow all the steps of healthy swimming.

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