IF YOU LIKE to splash in public swimming pools, you’ll want to read this. Think a chlorinated pool is a safe, sterile place? A study suggests the average pool may contain a great deal of urine.

Researchers set out to determine the extent of pee contamination in swimming pools. To do this, they tested water from pools and hot tubs for acesulfame potassium (Ace-K), a widely consumed artificial sweetener found in supermarket staples like frozen meals, packaged cookies, and diet sodas.

The amount of Ace-K in a pool is a helpful measure of the amount of urine present, since the ingredient is not metabolized by the body, is excreted exclusively through urine, and doesn’t get broken down by chlorine.

When researchers compared the levels of the sweetener in pool water and tap water, they found that the former contained up to 570 times more Ace-K. Based on those concentrations, they concluded that a 220,000-gallon commercial-size swimming pool likely contains almost 20 gallons of urine. A residential pool probably holds about two gallons.

The presence of pee in your pool isn’t just disgusting; it also raises real health questions, the researchers say. They point to recent studies that have shown bodily fluids like urine and sweat can react with disinfectants in the water to form disinfection by-products (or DBPs), compounds that may cause uncomfortable symptoms like eye irritation and respiratory problems.

What can you do about the pee problem? For one, don’t ‘go’ in the pool. Also make sure you rinse off before you jump in. A one-minute shower can remove much of the sweat that might react with disinfectants to form those health-compromising by-products.

One of the top causes of post-swim illness is a parasite called cryptosporidium (crypto for short), which leads to diarrhea, stomach pain and nausea. According to the new CDC report, of the 69 outbreaks associated with treated water, more than half were caused by crypto. Symptoms can last for up to two weeks. The parasite ends up in the water if feces (even trace amounts from someone who didn’t shower first) of an infected person gets in the pool. The bug is resistant to chlorine and survives outside the body for long periods.

Crypto spreads when you accidentally swallow contaminated pool water or you touch your mouth before washing your hands. Don’t touch your face until you’ve had your post-swim shower, with soap and hot water.

Burning eyes, excessive tearing and redness can occur because of an allergic reaction to chlorine, or an infection if the pool isn’t chlorinated enough. It can also happen if people aren’t showering before swimming or are peeing in the pool. Urine, as well as cosmetics and other chemicals that can wash off people’s skin, can irritate your eyes.

You can shield your eyes from all of this by wearing a pair of well-fitting goggles every time you go for a swim. By Manny Palomar, PhD (EV Mail Feb. 27-March 5, 2023 issue)