4 Health Risks of Over-Chlorinated Pools (and 7 Safety Tips)

Chlorine keeps pool water safe from bacteria and algae, but too much creates other health hazards

Here’s the irony: chlorine keeps pool water safe from bacteria and algae, but too much chlorine creates other health hazards.

“That ‘chlorine’ smell at the pool isn’t actually chlorine,” noted Chris Wiant, Chair of the Water Quality and Health Council, in a 2015 statement. “What you smell are chemicals that form when chlorine mixes with pee, sweat and dirt from swimmers’ bodies.” Personal care products can also interact with chlorine to form these secondary compounds. A 2010 study found more than 100 of them in indoor pools!

These volatile chemicals remain in the water, where they can be absorbed through the skin or swallowed, or hover in the air closest to the water, where swimmers breathe. Published research has found several health risks:

1. Bladder cancer has been linked to the effects of chlorine. Researchers found changes in key biomarkers (DNA damage that leads to cancer) after a 40-minute swim. “These are only biomarkers, not cancer itself,” noted the study’s lead author, an epidemiologist; “but in principle you don’t want to have things messing up your DNA.”

2. Asthma and allergy rates in children increase significantly with exposure to chlorinated pools. The Belgian researchers who conducted this study noted that kids who swam in pools with copper/silver purification suffered fewer instances of respiratory ailments.

3. Tooth decay can be notably worse among the most frequent indoor-pool swimmers, one study found. Chlorine increases the acidity of pool water, and if measures aren’t taken to balance the pH, it can damage tooth enamel. Symptoms included transparent or yellow teeth and pain when chewing.

4. Digestive ailments present a different sort of problem at public pools. Recent outbreaks of cryptosporidiosis, the main symptom of which is diarrhea, sent many people to the hospital. The parasite that causes it is now chlorine-resistant, so the remedy – excessive chlorination – raises the risk for the other chlorine-related problems.

Researchers in this field agree: the health benefits of regular swimming outweigh the risks. You can help to protect yourself (and others) with these Safety Tips:

1. Shower (and urinate) before getting into any pool.

2. Pool water should be clear, with little to no disinfectant odor, and the pool walls shouldn’t be slimy or sticky to the touch. If not, notify the management.

3. For asthmatics, watch to see if symptoms worsen in the hours after swimming; it may be an indicator that chlorination is a personal trigger.

4. Do not swim in a public/shared pool if you’ve had diarrhea in the last two weeks.

5. Seek out pools that use low-chlorine water quality systems. The Endless Pools® brand of swim-in-place pools utilizes copper/silver purifiers and UV systems to keep pool water safe with less chlorine than drinking water!

6. For pools that use traditional chlorination systems, favor outdoor pools when possible; the fresh air disperses toxic gases. Chlorine and its related compounds accumulate more in and around indoor pools.

7. If it’s within your means, consider a private home pool. With more compact models, such as Endless Pools, you’ll have an easier time maintaining water quality.