Healthy Swimming Pool FAQs
- Does swimming cause asthma?
- What about research from Belgium that found swimming in chlorinated pools can cause asthma in children?
- Can I get sick from using a swimming pool?
- How can I recognize a healthy pool?
- How can I protect myself and other swimmers?
- How do pool operators keep a swimming pool healthy?
- Does chlorine prevent all recreational water illnesses?
- Is chlorine safe for swimming pools?
- What causes “chlorine” odor, red eyes and itchy skin?
- What should I be asking my pool operator?
- How can I learn more about swimming pool health and safety?
There is no convincing evidence that swimming in chlorinated pools causes asthma in otherwise healthy people. In fact, physicians often prescribe swimming for their asthmatic patients. They say the benefits of swimming as a healthy form of exercise offsets any potential respiratory risk. Research on swimming pools and asthma center around substances formed in pool water called disinfection byproducts (DBPs), which form when disinfectants, such as chlorine, chemically react with impurities, including perspiration, body oils, urine and lotions introduced into the pool by swimmers. Some DBPs are highly volatile and can lead to noxious odors and irritating conditions, particularly at indoor pools. Properly operated and maintained pools should keep the level of DBPs low, while protecting swimmers from waterborne germs. Swimmers must also do their part by showering before swimming and never peeing in the pool.
In 2009, the Belgian Minister of Public Health became aware of a Belgian study linking children’s attendance at chlorinated pools to asthma development. The Minister instructed the Belgian Superior Health Council to formulate detailed scientific advice on this matter. The Council reviewed the Belgian study and other relevant publications and in February, 2011, produced an official report concluding the available evidence does not support advising children against swimming in chlorinated pools. The report is available in Dutch and French.
Swimming is a fun and healthy activity. However, contaminated water can still spread germs that cause recreational water illnesses (RWIs). RWIs cause a wide variety of symptoms, including skin, ear, respiratory and eye infections. The most commonly reported RWI is diarrhea. The U.S. Centers for Disease Control and Prevention (CDC) report that the number of RWI outbreaks has increased over the past decade. The CDC also warns that children, pregnant women and people with compromised immune systems are particularly at risk of more severe illness if infected.
Pool operators and swimmers can help maintain healthy water conditions with proper treatment and healthy swimming behaviors. Learn how in the answers below.
While you can’t see germs that cause RWIs, you can use your senses to help recognize the difference between a healthy pool and a potentially risky one:
- Sight: Look for water that’s clean, clear and blue – free from algae and unclouded. From the perimeter of the pool, you should be able to clearly see the drain or painted stripes on the pool floor. Also, look for drainage grills at the top of pool walls. Water should be constantly lapping over the grills to be filtered.
- Touch: Check for tiles that feel smooth and clean. Sticky or slippery tiles are caused by algae and other unwanted organisms. A hand full or scoop of water should disperse quickly and not stick to your hands.
- Smell: Chlorine helps keep pools healthy, and will not cause a strong chemical odor in a well-maintained pool. Strong chemical odors, as well as skin, eye or respiratory irritation, are caused by the high levels of chloramines, formed when chlorine combines with contaminants brought into pools by swimmers.
- Sound: Listen for pool cleaning equipment. Properly operating pumps help make sure that clean, chlorinated water reaches all parts of the pool, while filters physically remove debris.
Healthy swimming behaviors help prevent germs from contaminating the water in the first place. To protect yourself, your children and other swimmers from RWIs, follow these six recommendations from the CDC:
- Don’t swim when you have diarrhea. This is especially important for kids in diapers.
- Don’t swallow the pool water. In fact, try to avoid getting it in your mouth at all.
- Take a shower before swimming and wash your hands after using the toilets orchanging diapers.
- Take your kids on bathroom breaks or check diapers often. Waiting to hear “I have to go” may mean that it’s too late.
- Change diapers in a bathroom and not at poolside. Germs can spread to surfaces and objects in and around the pool.
- Wash your child thoroughly (especially the rear end) with soap and water before swimming.
Chlorine and pH are the first defense against germs that can make swimmers sick. Swimming pool operators should vigilantly monitor chlorine levels and pH, and make adjustments accordingly. The chlorine level in a pool should ideally be maintained between 2 and 4 parts per million (ppm), and should never fall below 1 ppm. The pH should be maintained between 7.2 and 7.8. Keeping the pH in the proper range will help maintain chlorine’s germ-killing power while minimizing skin and eye irritation.
Pool operators should also keep pool cleaning equipment running properly. Filters help remove debris, while pumps circulate clean, chlorinated water to all parts of the pool. In addition, periodic replacement of pool water helps reduce contaminants that are not removed in the treatment process.
The pool manager should also educate staff and swimmers about recreational water illnesses and develop policies concerning showering, restroom use and diaper changing that promote healthy swimming behaviors.
Chlorine in swimming pools kills the germs that may make people sick, but it takes time. Chlorine in properly disinfected pools kills most germs that cause RWIs within minutes. However, it takes longer to kill some germs such as Cryptosporidium that can survive for days in even a properly disinfected pool. Also, many things can reduce chlorine levels in pool water. Some examples are sunlight, dirt, debris, and material from swimmer’s bodies. Healthy swimming behaviors and good hygiene are needed to protect you and your family from RWIs and will help stop germs from getting in the pool.
Yes. Chlorine sanitizers are safe when used according to package directions approved by the U.S. Environmental Protection Agency. Chlorine levels within the recommended range for swimming pool water do not pose any known health risks. Chlorine sanitizers have been used safely and successfully as pool and spa disinfectants for over a century. The majority of public pools and 9 out of 10 residential pools are sanitized with chlorine.
These unpleasant conditions indicate that the pool water has not been properly treated. A common cause is high levels of chloramines, formed when chlorine combines with body oils, perspiration, urine and other contaminants brought into pools by swimmers. Contrary to what most people think, a strong chemical smell is not an indication of too much chlorine in the pool. In fact, the pool may actually need additional chlorine treatment to get rid of chloramines and sanitize the water. Good pool management, including proper ventilation of indoor pools, can significantly reduce chloramine levels in water and air. Swimmers can help, too, by showering before entering the pool.
Another important factor for swimmer comfort is the pH of the water. A swimmer’s body has a pH between 7.2 and 7.8. If the pool water isn’t kept in this range then swimmers will start to feel irritation of their eyes and skin.
Skin irritation can also be caused by germs. Skin infections (dermatitis) are commonly caused by the germ Pseudomonas aeruginosa. Infection can cause a bumpy red rash that usually appears within a few days of swimming in contaminated water. Proper pool maintenance is likely to control the spread of dermatitis.
A few basic questions to ask are:
- What specialized training was taken to prepare the operator and staff for running the pool?
- How often are the chlorine and pH levels checked?
- Are these levels checked during the time when the pool is most heavily used?
- Most health departments inspect pools — What was the health inspector’s grade for the pool in its last inspection?
Be proactive with just a few easy steps.
- Learn about recreational water illnesses and make sure your operator knows, too.
- Ask that pool management spread the word about RWIs to the pool staff and to pool users.
- Let your pool operator know that the health and well being of all swimmers is a priority.
Be a good consumer. Report problems to the pool manager, and contact your local health department if problems persist.
Swimmers, pool operators and public health officials can learn a wealth of information geared to their specific interests from:
CDC’s Healthy Swimming web site:
The National Spa and Pool Institute:
For downloadable list of these FAQs, please click here to download a PDF version.