Is Swimming in Chlorine Safe?

Chlorine is added to swimming pools to kill bacteria in the water, control organic debris, and prevent algae growth. However, swimmers who regularly swim in chlorinated pools are familiar with the side effects of chlorine. Red, itchy eyes, dry skin and hair, and a distinct lingering smell are all common. So is swimming in chlorine safe? The answer is complicated. Ultimately, it comes down to balancing the risks of chlorine versus the benefits (or the risks of not using it). For most swimmers, the danger should be minimal, but there are ways to minimize the possible side effects of swimming in chlorine.

Is Swimming in Chlorine Safe [infographic]

The Benefits of Chlorine

Chemicals such as chlorine and bromine are added to pools to keep the water clean. The biggest benefit of chlorine is that it kills germs that may be present in the water. If a pool were left unchlorinated it would become a petri dish full of all sorts of harmful bacteria. For that reason, all public pools and most private pools are treated with some amount of chlorine. Swimming in an unchlorinated pool would expose a swimmer to a whole host of potentially harmful bacteria, so the benefits of chlorine definitely seem to outweigh the risks.

How Much Chlorine is Safe

Undiluted chlorine would be poisonous if ingested. But in small amounts diluted in water, chlorine poses little risk. In fact, chlorine is added to drinking water to kill bacteria and make it safe to drink. The EPA regulates the amount of chlorine in drinking water. This ensures that there is enough to keep water safe from germs but not enough to be harmful when consumed. The EPA requires that there be some measurable level of chlorine in water to protect against water borne illness. It caps the permissible amount of chlorine at 4.0 ppm, which is low enough for safe consumption plus a wide margin of safety.

A well maintained pool should have levels of chlorine even lower than drinking water. The suggested amount of chlorine in a pool is 1.0 to 3.0 ppm. So in a well managed pool, the risk of chlorine exposure is minimal.

After adding chlorine to a pool, it is recommended to wait 4 hours or so before swimming. In any case, the best way to tell if a pool is ready to swim in is to test the chlorine level. Once the chlorine level has dropped below 5.0 ppm it should be safe to swim in. That’s barely more chlorine than the tap water we use for bathing, cooking, and drinking. However, the regularly maintained level of chlorine should be even lower.

The Risks of Unknown Compounds

The risk to swimmers from chlorine directly is very, very low. However, most chlorinated pools are full of all kinds of chemicals that were never intentionally added to the pool. Swimmers bring all sorts of compounds into the pool on their bodies. Sweat and urine introduce ammonia. Shampoos, conditioners, and body lotions all introduce a wide array of chemicals. When the chlorine in treated pool water reacts with these new chemicals, it can form volatile organic compounds. Some of these compounds are known to irritate the eyes and respiratory system. But the wide array of chemicals swimmers bring to the pool means that there are hundreds or even thousands of molecules and compounds that scientists don’t know about or haven’t studied.

Because many of these mystery compounds have not been studied, we don’t know if they are dangerous. There is anecdotal evidence of swimmers who have experienced reactions to pool water. This is especially true of indoor pools. In outdoor pools, many of these compounds dissipate into the air. But if an indoor pool is not properly ventilated, these compounds can accumulate.

HAA in Pool Water

Haleoactic acids (HAAs) are known to be dangerous at high enough concentrations. The EPA regulates their levels in drinking water. However, some studies have shown that these chemicals are present in pool water. Their presence is due to the reaction of chlorine with other chemicals introduced accidentally. One study found that 20 to 30 minutes after swimming swimmers had measurable levels of HAA in their urine. However, within three hours that HAA was eliminated from the body.

So what is the danger from HAA? The answer is that we don’t know. While HAA is one example of the many chemical compounds formed in chlorinated pools, we don’t know much about it. It is unclear what, if any, health effects it may have at these levels. This is typical of the compounds created when chlorine reacts with chemicals unintentionally introduced into the water.

How to Minimize the Risk from Chlorinated Pool Water

Although swimming in chlorinated pools is generally considered safe, there are ways to make it even safer. Limiting exposure is the easiest way to stay safe. One way to do this is just to swim less. But for some, this is not a great solution. Competitive swimmers, or even just people who love swimming, often spend many hours day after day in chlorinated pools. For some swimmers, smelling like chlorine can be a badge of honor.

If you plan to spend a lot of time swimming, another way to minimize exposure is to swim outdoors. Many of the harmful compounds formed from reactions with chlorine become gases. In an outdoor pool, these gases are simply blown away or dissipate into the air. If you are swimming in an indoor pool, make sure that there is adequate ventilation. If you walk into an indoor pool space and smell the pool strongly, that indicates inadequate ventilation. What you are smelling is likely not the chlorine. Instead, you are smelling the mixed odor of a whole host of compounds that we know little about.

Chlorine itself can enter the body through the skin. Mucous membranes, eyes, and areas of thin skin such as around the anus allow more chlorine to penetrate. However, 90% of the chemical exposure likely comes from swallowing water. Something as simple as keeping your mouth closed while swimming can drastically reduce chemical exposure. Goggles can reduce chemicals that enter the body through the eyes. If you really wanted to limit exposure you could wear a wetsuit, though there is little evidence that such a drastic move is necessary.

Keeping Pool Water Safe

A few simple rules can help keep pool water safer. Most of the potentially harmful compounds are caused by reactions with chlorine. So reducing the amount of unintentional chemicals introduced into the pool water can help keep the water safer for everyone.

The first rule is to shower immediately before and after swimming. Showering before swimming can help wash off much of the ammonia carried in sweat. It also washes off the lotions, shampoos, conditioners, and other chemicals we carry on our bodies and in our hair. Showering immediately after swimming washes off most of the compounds found in the pool water. Both when showering before and after pool use, it is important to use a good natural soap. Soap helps dislodge chemicals from the hair and skin. Using a simple, chemical free natural soap before swimming limits the chemicals that will enter the water with the swimmer. In any case, make sure the rinse off well when showering before and after swimming.

Finally, the age old wisdom of swimmers everywhere remains true. Do not pee in the pool. Although the pool water is chlorinated, or even because pool water is chlorinated, peeing in the pool can cause an accumulation of harmful chemical compounds.

Manage Your Pool Water

The most important way to keep your pool water safe is to manage the chemical levels of your pool water. Keeping your water balanced will minimize the risk from high or low pH, overexposure to chlorine, and other issues arising from pool water exposure. Of course, keeping pool water balanced is a lot of work. If you feel you don’t have the time or expertise to balance your pool water regularly, The Pool Butler can help. With our white glove service we can come to your pool on a regular basis to monitor and maintain chemical levels. So if you are ready for crystal clear, safe, clean pool water, give us a call. You can contact us online or call us at 770-439-2644. We look forward to hearing from you!

Posted in

The Pool Butler