Swimming-related Illnesses

Image of a young boy with goggles in the pool

Swimming-related illnesses are diseases that people can get from the water in which they swim and play—like swimming pools, hot tubs/spas, splash pads, or oceans, lakes, and rivers—if the water is contaminated with germs.

What are the most common symptoms?

The most common symptoms caused by swimming-related illnesses are diarrhea, skin rashes, ear pain, cough or congestion, and eye pain.

How are swimming-related illnesses spread?

You can get swimming-related illnesses if you swallow, have contact with, or breathe in mists or aerosols from water contaminated with germs. You can also get them by having contact with chemicals that are in the water or that evaporate from the water and turn into gas in the air.

Diarrhea is the most common swimming-related illness. People who are already sick with diarrhea can spread it to others when they get in recreational water. People typically have about 0.14 grams of poop (similar to a few grains of sand) on their bodies at any given time. When a person who is sick with diarrhea gets in the water, that tiny amount of poop on their body can wash into the water around them and contaminate it with germs. If someone else swallows the contaminated water, they can become infected.

Other swimming-related illnesses—such as skin, ear, respiratory, eye, and other infections—can be caused by germs that naturally live in the water and soil. If the chemicals used to kill germs (chlorine or bromine) in pools, hot tubs, and water playgrounds are not kept at the right level, these germs can multiply and make swimmers sick.

Who is most at risk?

Children, pregnant women, and people who have health problems or take medicines that lower their body’s ability to fight germs and sickness—such as people whose immune systems are weakened because of cancer, an organ transplant, or HIV—are most at risk for swimming-related illnesses.

People with weakened immune systems should be aware that recreational water might be contaminated with Cryptosporidium (or Crypto for short). Crypto can cause life-threatening symptoms in people with weakened immune systems.

People with weakened immune systems should consult their healthcare provider before participating in recreational water activities, such as swimming.

How can swimmers protect themselves and others from swimming-related illnesses?

The best way to prevent swimming-related illnesses from spreading is to keep germs out of the water in the first place. This means that if you or your child has been sick with diarrhea in the past two weeks, you should stay out of the water.

To protect yourself from the most common swimming-related illnesses:

  • Keep water out of your mouth when you swim
  • Dry your ears after you swim

Why is disinfection important to help stop the spread of swimming-related illnesses?

Disinfection with chlorine or bromine and pH is the first defense against the germs that cause swimming-related illnesses in pools, hot tubs/spas, and water playgrounds. At the recommended levels, chlorine or bromine can kill most germs in the water within minutes (some germs, such as Crypto, can live in properly treated water for days).

Image of two girls swimming in pool

Learn all of the ways to protect yourself and your loved ones from swimming-related illnesses by following CDC’s steps for healthy swimming.

However, one CDC study found that more than 10% of routine inspections of public pools, hot tubs/spas, and water playgrounds (for example, at hotels/motels and waterparks) led to immediate closure because of serious violations, such as improper chlorine or bromine levels. Swimmers can check for adequate free chlorine (1–3 parts per million or ppm in pools/water playgrounds and 3–10 ppm in hot tubs/spas) or bromine (3–8 ppm in pools/water playgrounds and 4–8 ppm in hot tubs/spas) and pH (7.2–7.8 in all types of water) levels using test strips. 

What germs most commonly cause swimming-related illness outbreaks?

From 2015 to 2019, 208 treated recreational water swimming-related illness outbreaks were reported to CDC. The most commonly reported illnesses were:

  • Acute gastrointestinal illness (such as diarrhea or vomiting)
  • Skin illnesses (such as rash)
  • Acute respiratory illness (such as cough or congestion)

Ranking

Ranking

Ranking

Germ/Cause

Germ/Cause

Germ/Cause

Predominant Illness

Predominant Illness

Predominant Illness

1

Ranking

1

AGI (acute gastrointestinal illness)

Predominant Illness

AGI (acute gastrointestinal illness)

2

Ranking

2

Germ/Cause

ARI (acute respiratory illness)

Predominant Illness

ARI (acute respiratory illness)

3

Ranking

3

Germ/Cause

AGI

Predominant Illness

AGI

4

Ranking

4

AGI

Predominant Illness

AGI

5 (tied)

Ranking

5 (tied)

Germ/Cause

AGI

Predominant Illness

AGI

5 (tied)

Ranking

5 (tied)

ARI

Predominant Illness

ARI

*Treated recreational water is water in a pool, hot tub, splash pad or other artificially constructed structure that is intended for recreational or therapeutic purposes. This table ranks pathogens by the total number of cases of illness that they caused.

Page last reviewed: July 1, 2022