Salt water versus chlorinated pools: What's the difference?


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Ever wonder what the difference is between chlorinated and salt water pools? And why do some fitness facilities choose one over the other? Between cheaper maintenance costs and more health-conscious clients, it’s no wonder salt water pools are trending nationwide. However, keep in mind that both systems use chlorine on some level.

The case for chlorine

If you’ve read the headlines lately, you may seriously be considering a switch from a gym that has chlorinated swimming pools to one with salt water. The ultimate reason: pee.

Not only is it gross and unsanitary when someone tinkles anywhere other than a toilet, new research published in Environmental Science & Technology shows that when mixed, urine and chlorine can form substances that can cause potential health problems. Two popular compounds found in pools are trichloramine (NCl3), which is associated with lung problems, and cyanogen chloride (CNCl), which can also affect the lungs, as well as the heart and central nervous system.

While chlorine kills harmful bacteria in swimming pools and in our drinking water, byproducts like haloacetic acids (HAAs) — a potentially dangerous chlorine byproduct — occur when chlorine reacts with impurities in the water, according to WebMD.

In addition, a study published in 2011 showed that HAAs appeared in the urine of swimmers 20 to 30 minutes after exposure and were eliminated from the body within three hours. Normal exposure to a chlorinated pool shouldn’t’ be enough to do much harm, but it’s disturbing that high levels of HAA are banned in drinking water by the EPA because high amounts may be linked to birth defects and cancer. Why would we want any in our pools?

"Well-managed pools should have concentrations that are less than what is found in drinking water," said Mary Ostrowski, director of chlorine issues for the American Chemistry Council in Washington, D.C., on WedMD. "In a properly maintained pool, any risk is likely to be very small."

Salt water surprise

Salt water pools are becoming more popular in the United States. They are less harmful to the body and although they cost more upfront, they are cheaper to maintain in the long run. Working out in a salt water pool is gentler on your eyes, won't dry out your skin, and won't bleach your hair and bathing suit like a chlorinated pool can.

So how do they create a salt water pool. They don't just dump table salt in and call it a day. Saline — the same stuff you use to clear your sinuses with a neti pot — is added, making the water less salty than your tears and softer with hardly any salty taste. According to Style at Home, salt concentration in the pool tops out at about 2,800 to 4,000 parts per million, compared with 50,000 parts per million in ocean water.

Don’t be fooled: Salt water pools do have a low concentration of chlorine as a disinfectant. Salt is pumped into an electrolytic cell where it's converted into chlorinated water and pumped back into the pool. At the same time, explains Style at Home, the chlorine created is constantly recombining with the sodium, becoming good old salt again. It's a closed, continuously regenerating process.

Wow, science.