Frequently Asked Questions

Below are the answers to frequently asked healthy swimming and recreational water questions on healthy swimming and recreational water topics. This page has information for the public and pool and public health professionals. Topics covered include important information on diarrhea, recreational water illnesses (RWIs), plastic pools, water play areas, and how to disinfect pools, among others.

For the Public

• What’s an "RWI"?
• Can I get diarrhea from swimming?
• What should I do if I have diarrhea?
• Can I get head lice from a swimming pool?
• Can I get pinworm from a swimming pool?
• What is "hot tub rash"?
• What causes stinging eyes, nose irritation and/or breathing difficulty at the pool and what can I do about it?
• Can my child get sick from swimming in an inflatable or plastic pool?
• Do swim diapers/swim pants prevent germs from spreading?

What's an "RWI"?

RWI stands for "recreational water illness," which is an illness caused by germs spread by swallowing, breathing in mists or aerosols of, or having contact with contaminated water in swimming pools, hot tubs, water parks, water play areas, interactive fountains, lakes, rivers, or oceans. RWIs can also be caused by chemicals in the water or chemicals that evaporate from the water and cause indoor air quality problems.

To learn more about RWIs and how you can prevent them, please see the Basics of Recreational Water Illness (RWI) page.

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Can I get diarrhea from swimming?

Yes. You share the water — and the germs in it — with every person who enters the pool. Infectious diarrhea can contain anywhere from hundreds of millions to one billion germs in each bowel movement. This means that a single diarrheal incident from one person could contaminate water throughout a large pool system or waterpark. Swallowing even a small amount of water that has been contaminated with these germs can make you sick. That is why it is so important to stay out of the pool if you are sick with diarrhea, shower before swimming, and avoid swallowing pool water.

At public swimming facilities, continuous filtration and disinfection of water should reduce the risk of spreading illness. However, swimmers may still be exposed to germs during the time it takes for chlorine to kill germs (certain germs take longer to kill than others) or for water to be recycled through filters.

For more information, please see Diarrhea and Swimming and CDC’s Chronic Diarrhea page

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What should I do if I have diarrhea?

To help protect the health and safety of others, do not swim if you have diarrhea or if you have had diarrhea. Microscopic amounts of fecal matter containing germs can contaminate an entire pool or hot tub and make others sick if they swallow the water.

For more information on diarrhea, please see Diarrhea and Swimming and CDC's Chronic Diarrhea page.

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Can I get head lice from a swimming pool?

Head lice are unlikely to be spread through the use of swimming pools. Head lice survive by holding onto hair and, although pool chlorine levels do not kill lice, the lice are not likely to let go when a person's head goes under water.

Head lice can be spread by sharing towels or other items that have been in contact with an infected person's hair. To protect yourself from head lice at the pool, do not share towels, hair brushes, or other items that come into contact with someone else’s hair. If you already have lice, do not swim or wash your hair within 1–2 days of treating it with anti-lice shampoo — these actions will make the treatment less effective.

For more information on head lice, please visit CDC's Lice page.

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Can I get pinworm from a swimming pool?

Pinworm infections are rarely spread through the use of swimming pools. Pinworm infections occur when a person swallows pinworm eggs picked up from contaminated surfaces or fingers. Although chlorine levels found in pools are not high enough to kill pinworm eggs, the presence of a small number of pinworm eggs in thousands of gallons of water (the amount typically found in pools) makes the chance of infection unlikely.

For more information on pinworm, please see the Pinworm and Swimming page and CDC's Pinworm Infection page.

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What is "hot tub rash"?

Dermatitis, also known as "hot tub rash," is an infection of the skin that occurs from extended exposure to contaminated water. Hot tub rash is caused by the germ Pseudomonas, which is common in the environment (water, soil). Symptoms of hot tub rash include:

• Itchy spots on the skin that become a bumpy red rash
• Rash worse in areas previously covered by swimsuit
• Pus-filled blisters around hair follicles

Hot tub rash can occur if disinfectant levels in the hot tub water are low, allowing the Pseudomonas to multiply. To protect yourself from hot tub rash, follow these steps:

1. Ask your pool manager about the disinfectant and pH testing program at your hot tub. Ensuring frequent testing, appropriate disinfectant (usually chlorine or bromine) levels, and pH control are key.
2. Check the disinfection levels with test strips.
3. Remove swimsuits and shower with soap after leaving the hot tub.
4. Clean swimsuits after leaving the hot tub.

For additional information on hot tub rash, please see the Hot Tub Rash page.

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What causes stinging eyes, nose irritation and/or breathing difficulty at the pool and what can I do about it?

Many people experience stinging eyes, nasal irritation, or difficulty breathing after being in the water or breathing in the air at swimming pools, particularly indoor pools. These symptoms are typically caused by a build-up of irritants, known as chloramines, in the water and air. This build-up is usually caused by poor air circulation and lack of fresh air in the pool area.

To avoid this problem at home, you can open doors or windows to increase the amount of fresh air coming through the room. You can also turn on a fan to help boost the air flow over the pool surface. Good hygiene practices, such as showering before entering the pool and using the bathroom regularly (to avoid urinating in the pool), will also help reduce the amount of irritants in the air and water.

In a public setting, ask your pool operator to open any doors or windows and suggest that they use a fan to increase air flow. You can also suggest that pool operators visit our Irritants (Chloramines) & Indoor Pool Air Quality page for more information.

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Can my child get sick from swimming in an inflatable or plastic pool?

Yes. Small inflatable pools, hard plastic pools, and other small water-play equipment (for example, inflatable slides where water collects at the bottom) have been associated with the spread of germs. Germs can be spread by swallowing or having contact with water that has been contaminated with infected feces.

Adding germ-killing chemicals (such as chlorine bleach) to the water in these small pools is not recommended because it is difficult to determine the proper amount that should go in the pool.

Because disinfection is not a safe or feasible option, using these pools increases the risk of spreading germs brought in to the water by swimmers with diarrhea. Therefore, CDC does not recommend the use of small inflatable and hard plastic pools in child care programs (large or small) or schools.

Any household deciding to use these types of small pools should become familiar with the steps necessary to reduce the risk of spreading germs in the water. For these steps and additional information on small pool safety, please see the Inflatable and Plastic Pools page and CDC's Water-related Injuries Facts page.

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Do swim diapers/swim pants prevent germs from spreading?

The use of swim diapers and swim pants might give users, parents, and pool staff a false sense of security regarding water contamination caused by feces (poop) and germs.

Even though swim diapers and swim pants might hold in some solid feces, they are not leak proof. Swim diapers and swim pants can delay diarrhea-causing germs, like Cryptosporidium, from leaking into the water for a few minutes, but swim diapers do not keep these germs from contaminating the water. It is unlikely that swim diapers are able to keep diarrhea, the most serious water contaminant, from leaking into the pool.

All swimmers should stay out of the water when they are ill with diarrhea, even if they are wearing swim diapers or swim pants. They risk contaminating the pool with feces and germs, which can make others sick.

Swim diapers and swim pants are not a substitute for frequent bathroom breaks and diaper changing. It is recommended that swim diapers and swim pants are checked frequently (approximately every 30 to 60 minutes) and changed away from the poolside.

For more information on swim diapers/swim pants, please see the Swim Diapers and Swim Pants page.

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For Pool Operators and Public Health Professionals

• How long does it take for chlorine to kill germs in a pool?
• Why is it important to clean surfaces around the pool area?
• What do I need to know about water play areas and interactive fountains?

How long does it take for chlorine to kill germs in a pool?

Free chlorine kills most bacteria such as E. coli 0157:H7 in less than a minute if it is maintained at proper disinfection levels (1–3 parts per million [ppm] free chlorine) and under ideal water conditions (pH at 7.5 or less; temperature at 77° F [25° C] or more) throughout the pool. However, a few germs are moderately (Giardia, Hepatitis A) to highly (Cryptosporidium) chlorine-tolerant.

For more information on how long it takes to kill common illness-causing germs, please see the Chlorine Disinfection Timetable.

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Why is it important to clean surfaces around the pool area?

Germs can be spread by contact with contaminated surfaces. To prevent the spread of germs, it is crucial that pool operators keep the surfaces in or around swimming pools clean. Many times, poolside lounge tables and chairs are used for diaper-changing and microscopic amounts of fecal matter can remain on their surfaces when the changing is over. The germs in this fecal matter can be easily spread to the next person using the pool furniture.

Play structures in and around the pool that are not properly cleaned can also become covered in germs from unwashed hands. In some instances, a slime layer will develop, which can protect germs from disinfection.

To reduce the spread of germs, follow these steps:

• Provide clean and convenient diaper changing areas (such as restrooms) so that parents are less likely to change diapers at poolside.
• Explain to patrons why it is important to change diapers in designated diaper-changing areas.
• Clean poolside structures with chlorinated water.
• Scrub in-pool structures to remove the build-up of slime (biofilm)

For more detailed information on cleaning pool surfaces, please see the Cleaning Up Body Fluid Spills on Pool Surfaces page.

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What do I need to know about water play areas / interactive fountains?

A more recent addition to the recreational water scene is the water play area (may also be called an interactive fountain, wet deck, splash pad, spray pad, or spray park). People may not realize that although there is no standing water in these attractions, the spray water will rinse any contaminants (for example, diarrhea, vomit, and dirt) down into the water holding area and be sprayed again. In other words, the water is recycled through the system. As a result, it is possible for the water to become contaminated and cause outbreaks of illness.

Because water play areas are relatively new, health departments may not have specific requirements for how this water is treated. It pays to be proactive by building water play areas or interactive fountains like any other water attraction is built. They should include adequate disinfection and filtration systems even if this is not currently required by the local or state pool code. The addition of secondary disinfection, like ultraviolet light or ozone, should be considered and is now required in New York State. Health departments should also ensure that pool codes are updated to include water features that do not have standing water.

For more information on water play areas and interactive fountains, please see the Water Play Areas & Interactive Fountains page.

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