Public Health Corner: Recreational water illness

Recreational water illnesses (RWIs) are caused by the germs found in the water people swim in. Examples of water that can be contaminated include swimming pools, hot tubs, water parks, water play areas, decorative fountains, lakes, rivers, and oceans.

The most common bacteria that causes RWIs is cryptosporidium, often called “Crypto” for short. Additional pathogens include: campylobacter, giardia, shigella, E. coli, norovirus, leptospira, and plesiomonas. Summertime, especially the month of August, is the peak occurrence for RWIs.

RWI infections can occur in the gastrointestinal tract (stomach and intestines), ears, eyes, skin, and central nervous system. Diarrhea is the most common symptom. Additional symptoms can include stomach cramps, nausea, vomiting, fever, and dehydration. It takes only a small amount of water that is contaminated by any of these germs to make an individual sick.

The germs that cause RWIs are typically carried into the water in or on our bodies. These microbes or germs are so small they are undetectable to the human eye and are ingested by mouth. Stool or fecal matter from an infant’s swim diaper or a bowel accident from a toddler can be an obvious culprit, but individuals who have long been toilet trained can also be the cause.

When people are ill with diarrhea, even a speck of their stool can contain millions of germs. Swimming while ill can easily contaminate the water – even if you don’t have an accident. Also, lakes and rivers can be contaminated by animal waste, sewage spills, and water runoff following rainfall. If you swallow water that has been contaminated, you may become sick.

Because of this, any person regardless of their age who has diarrhea should absolutely not go into the water. They are contagious and could likely pass their illness to other swimmers.

Healthy swimmers should always shower before getting into the water. Simply rinsing off in the shower for 1-2 minutes removes a significant amount of dirt and bacteria off the surface of your body.

In an effort to reduce the likelihood of harmful bacteria in public pools and water parks, management is required to regularly check the pH levels, along with the chloride and bromide levels. These two common chemicals are used to treat recreational water in an effort to kill most bacteria after several minutes. It should be noted that both cryptosporidium and giardia have a strong outer shell and can persist in treated water for more than 10 days.

Because of this, swimmers should attempt to limit the amount of water they swallow. Parents of small children should use appropriate swim diapers and monitor them frequently and change as necessary. Swimmers of all ages need to be responsible and not swim if they have been recently ill. To avoid transferring germs to other swimmers, you should always shower before and after entering the water, along with never urinating or defecating while swimming.

Regardless of how fun and inviting the water looks, those with compromised immune systems, the elderly, pregnant women, and children are at a greater risk for contracting a RWI.

Additional information on RWIs can be found on the Minnesota Department of Health’s website: