Hot tubs are very, very cozy
Swimming in any body of water exposes you to skin cells, urine, and other contaminants. Pools have a large amount of water to disperse them, but hot tubs hold less water. “You’re bathing in close quarters with however many of your friends are with you,” says Kelly Reynolds, PhD, microbiologist and associate professor in the public health college of the University of Arizona. With less water to dilute any contaminants, the concentration is higher in a hot tub.
It’s hard to keep chlorine levels up to snuff
Those tight quarters also make it tough to keep up with a hot tub’s chlorine demands. Chlorine sticks to skin cells, sunscreen, and body oils, meaning you’re taking some out with you when you’re done soaking. Every time you hop in and out, you mess with the levels even more. “When you get out of a hot tub or swimming pool and smell chlorine on your skin, you’ve taken some of that chlorine with you,” says Dr. Reynolds. “You’re just increasing the chlorine demand by going in and out and bringing debris into the hot tub.” Public hot tubs usually get checked multiple times per day, but you probably aren’t as diligent with your private one. Dr. Reynolds recommends testing the levels more often, and showering before hopping in the hot tub to rinse off any oils. Find out the healthiest shower temperature.