May 22, 2017

Diarrheal Outbreaks Frequently Linked to Swimming Pools

Survey finds that one in four adults would swim while sick with diarrhea

Survey links diarrheal outbreaks to swimming pool water

A survey conducted on behalf of the Water Quality and Health Council found that one in four adults (25%) would swim within one hour of having diarrhea, half of adults (52%) seldom or never shower before swimming in a pool, and three in five adults (60%) admit to swallowing pool water while swimming.

These results are concerning to experts from the U.S. Centers for Disease Control and Prevention (CDC), the Water Quality and Health Council, and the National Swimming Pool Foundation (NSPF), given that waterborne outbreaks of diarrheal disease caused by the germ Cryptosporidium (Crypto) remain a challenging health concern.

Crypto is a parasite that can spread when someone swallows water that has been contaminated with the fecal matter of an infected swimmer. Crypto is the most common cause of diarrheal illness and outbreaks linked to swimming pools or water playgrounds. In addition to diarrhea, some people experience lack of appetite, nausea, vomiting, weight loss, stomach cramps or pain and fever.

The CDC advises those infected with Crypto to avoid swimming until two weeks after recovering from diarrhea. Parasites can remain in the small intestine for weeks and cause symptoms to reappear days after the infected person recovers.

"Normal chlorine disinfection of swimming pool water does a great job in destroying most germs, but Crypto presents a special challenge," said Chris Wiant, chair of the Water Quality and Health Council. "An awareness of Crypto helps us remember that a healthy pool depends on swimmers being considerate of one another. Showering before swimming, refraining from peeing in the pool, and not swimming for two weeks after experiencing diarrhea can help keep swimming fun and healthy for everyone from 'water babies' to seniors."

Other key findings of the national Healthy Pools survey include:

  • 72% of adults are unaware that Crypto is a parasite often spread in water; and
  • 84% of adults are unaware that the use of chlorine at CDC-recommended levels will not kill Crypto instantly in swimming pools.

“Crypto is not easily killed by chlorine and can live up to 10 days in well-treated pools,” said Michele Hlavsa, RN, MPH, epidemiologist and chief of the CDC’s Healthy Swimming program. “Just a small number of Crypto germs can make someone sick. That’s why it is important to keep Crypto out of the water in the first place.”

Swimmers and parents of young swimmers can take a few easy steps to prevent Crypto outbreaks:

  • Stay out of recreational water (e.g., pools, lakes, rivers, oceans) if sick with diarrhea and until diarrhea-free for two weeks. Patients typically continue to shed Crypto for up to two weeks after diarrhea stops.
  • Shower before you get in the water. Rinsing off in the shower for just one minute removes most of the dirt or anything else on your body.
  • Don’t swallow the water.
  • Report diarrhea incidents that occur in the water to aquatics staff immediately.

Drowning prevention is also key to maintaining a healthy and safe swimming experience. According to the survey, 60% of parents reported engaging in some type of distracted activity while their children swam in a pool, such as using a phone or tablet, reading a book, drinking alcohol, sleeping or leaving the pool altogether.

“Parents should designate a ‘Water Watcher,’ because supervision can save a life,” said Thomas Lachocki, Ph.D., CEO of NSPF. “Water Watchers are important even if a lifeguard is present. Water Watchers should be at least 16 years old and able to recognize and execute a rescue, provide a floating or reaching object, alert someone nearby to help or call 911, and be able to administer CPR.”

The Water Quality and Health Council is making free pool test kits available this summer through its Healthy Pools awareness initiative. Swimmers can test their backyard pools or community pools to ensure a proper pH and chlorine level. Visit to order a free pool test kit.

The 2017 Healthy Pools survey was conducted online by Sachs Media Group, an independent research firm based in Tallahassee, Fla. Sachs Media Group interviewed 3,114 adults (at least 18 years old), April 28 to 30, 2017. The survey measured perceptions and misconceptions related to swimming pools and public health, with a margin of error of +/- 2.0%.