Health & Fitness

How to avoid waterborne illnesses

Summertime for many people means heading out to their favorite lake or swimming hole to cool off. However, thousands of Americans every year get sick from those recreational waters.

Germs spread through contaminated water in swimming pools, water parks, hot tubs, oceans, lakes and rivers. Illnesses from swimming or playing in water can range from skin, ear or eye infections to gastrointestinal illness. The most commonly reported recreational water illness is diarrhea, which can be caused by germs such as Cryptosporidium, Giardia, Shigella, norovirus and E. coli.

Swimmers share the water – and the germs in it – with every person who enters the swim area. If someone is ill with vomiting or diarrhea, even a tiny amount of their vomit or stool can contain millions of germs. This means that just one sick person can easily contaminate the water in a pool or swim area.

Natural bodies of waters, such as lakes and rivers, are exposed to even more contaminates. They can be contaminated with animal waste, stormwater or sewage from failing septic systems.

Most public swimming pools are chlorinated to provide disinfection, but the amount of chlorine can easily be overwhelmed when there are many people. Natural bodies of water are not disinfected, even when the water looks clean. To keep from spreading illness or becoming ill from recreational water, follow these simple steps.

Do not swim when you have vomiting or diarrhea. Stay out of pools and swim areas for at least two weeks after the illness and/or treatment stop. Studies show you may still spread disease even though you feel better and have no symptoms.

Do not swim if you have a skin infection.

Avoid large crowds of bathers. The more swimmers present, the higher the risk of catching an illness.

Try not to swallow pool or lake water or get it in your mouth.

Shower before and after swimming. Children too!

Always wash your hands before eating.

Take children on bathroom breaks frequently or change diapers often. Change children’s diapers in a bathroom, not at poolside or on the beach. Germs can spread from a diaper changed on a lounge chair or table. Wash your hands after using the toilet or changing diapers.

People with fragile immune systems should reconsider water recreation in public pools or natural waters.

If you experience illness two to 10 days after swimming and know of others who are also ill after the same exposure, you may be part of a waterborne disease outbreak. Check with your health care provider; laboratory tests may be needed.

To report an outbreak of illness after swimming, call Thurston County Surface Water Program at 360-867-2626. For more information, go to Look for the link “Swimming in Thurston County” toward the bottom of the page.

Dr. Diana T. Yu is the health officer for Thurston and Mason counties. She can be reached at 360-867-2501 or