"Most Athletes Urinate"…Swimming Pools, the Dirtiest Secret of the Olympics

WSJ "All Swimmers Pee in the Pool"
Long Time Needed to Put on Racing Swimsuits Again
"Rule Is Not to Pee Near Other Swimmers"

'Absolutely no urinating or nose blowing in the swimming pool' is a basic guideline posted in many swimming pools, but reports have emerged that most athletes competing in Olympic swimming events actually urinate in the pool during competitions. On the 26th (local time), the U.S. Wall Street Journal (WSJ) reported, "Every swimmer competing in the Olympics urinates in the pool at the Paris La D?fense Arena where the events take place," calling it "the dirtiest secret of the Olympic Games."

This behavior is presumed to be due to the swimsuits the athletes wear. Swimmers competing in events wear tight, muscle-compressing racing swimsuits. These help reduce water resistance but are so tight that putting them on and taking them off is not easy. The problem is that they need to stay well hydrated right up until the competition.

They want to drink water and urinate, but putting the swimsuit back on can take up to 20 minutes. Ultimately, they have no choice but to urinate in the pool. However, it is said to be an unspoken rule not to urinate when others are nearby. Lilly King, who competed in three Olympics as part of the U.S. team, told WSJ, "I peed in every pool I ever swam in."

Jack Harting, who represented the U.S. at the 2020 Tokyo Olympics, also shared a similar experience from his high school championship days. He said, "Right before a swim race, I suddenly needed to use the bathroom, but taking off the tight swimsuit was even harder. As a result, I urinated in the water while still wearing the suit, and later found it convenient and repeated it."

The reason this is possible is thanks to the large amount of chlorine added to the pools. Brian Spear, who managed water quality at the U.S. Olympic trials pool, explained, "During the nine-day trials with 1,000 athletes competing, we constantly adjusted the pH and chlorine levels to keep the water clean."

It is also common for public pool users to urinate in the water. A 2017 study by the University of Alberta in Canada found that public pools contain an average of 75 liters of urine. The researchers measured the concentration of acesulfame potassium (ACE), an artificial sweetener commonly used in processed foods like sodas and baked goods, to estimate how much urine was present in the pools.

The results showed that a 500,000-liter pool (approximately 25m long, 6 lanes, 1.4m deep) contained an average of 32 liters of urine, while a 1,000,000-liter pool (about half the size of an Olympic pool) contained nearly 90 liters. In terms of concentration, these correspond to 0.0064% and 0.009%, respectively.