There isn’t really a chemical that makes water turn a darker color when someone urinates in a pool, but two new reports on the health risks of pools, hot tubs and water playgrounds might make you wish there were.

One report by the Water Quality and Health Council asked 3,000 adults about their swimming habits for its yearly Healthy Pools report. Among the questions was whether they had urinated in a pool as an adult; some 27 percent of adults — more than one in four — said they had.

“And we think that’s probably underreported,” said Chris Wiant, chairman of the Water Quality and Health Council, which is funded by the American Chemistry Council to survey swimmers’ behaviors.

Urine will combine with the chlorine in the pool to create other chemicals, leaving less chlorine available to act as a disinfectant and kill bacteria (and the chemical byproducts created will irritate your eyes).