Summer fun means water. But be careful.

In a study released Friday, the Centers for Disease Control and Prevention reminded Americans that the bodies of water they play in can sometimes make them sick.

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From 2000 to 2014, the years of the study, voluntary reporting from 35 states and Guam turned up nearly 5,000 reports of sickness — and two deaths — related to bodies of water that had not been treated. The majority of untreated water places were public parks and beaches.

The study also lists outbreaks in treated water.

In Georgia, over the last four years of the study, by far the most sicknesses reported involved a members-only club, in its wading pool. In August 2014, 63 people were sickened there with the parasite Cryptosporidium hominis, a pathogen that can cause dangerous diarrhea.

None were hospitalized, though. In contrast, in August 2013, five people were reported sick and three were hospitalized, with Legionella pneumophila believed to come from a Georgia hotel pool. That's the bacterium that can cause Legionaire's disease.

Others were sickened in community parks or water parks.

But there are things swimmers can do to lessen the risk.

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“Swimmers and parents of young swimmers can take steps to minimize the risk for exposure to pathogens, toxins, and chemicals in untreated recreational water,” the CDC report said, “by heeding posted advisories closing the beach to swimming; not swimming in discolored, smelly, foamy, or scummy water; not swimming while sick with diarrhea; and limiting water entering the nose when swimming in warm freshwater.”

Things to know:

  • Ocean beaches were rarely the source of the problem in the study, but the federal government maintains a resource to check them for closure and scientific detail on the water quality: https://watersgeo.epa.gov/beacon2/

Stay out of the water if

  • The beach is closed or an advisory is posted for high bacterial levels or other conditions, such as sewage spills or harmful algal blooms.
  • A recent heavy rain has occurred.
  • A discharge pipe can be seen on the beach.
  • Fish or other animals in or near the water are dead.
  • Water is discolored, smelly, foamy or scummy.

Other don’ts

  • Don't swim or let children swim if sick with diarrhea.
  • Don't swallow recreational swimming water.
  • Don't swim near or wade in marshy areas where snails are commonly found.
  • Don't put your head under the water in hot springs or other untreated thermal waters.

And if there’s algae

  • Avoid water that contains harmful algal blooms.
  • Rinse off pets, especially dogs, immediately if they swim in discolored, smelly, foamy or scummy water. Do not let them lick the algae off their fur.