Scientists who study this sort of thing have determined that indeed, people do pee in swimming pools and hot tubs - and pretty frequently.
The test works by measuring the concentration of an artificial sweetener, acesulfame potassium (ACE), that is commonly found in processed food and passes through the body unaltered.
In total, the team sampled 31 different pools and tubs in two Canadian cities and found ACE to be present in 100% of the samples, with concentrations up to 570 times the background level in tap water samples. They used the average ACE concentration in Canadian urine to convert their measurements into approximate volumes of urine.
One hotel Jacuzzi had more than three times the concentration of sweetener than in the worst swimming pool.
The pause that refreshes. But as if, with the recent heavy rains and associated flooding, folks in San Diego didn't already have enough to deal with, they've now got a fecal matter on their hands. And they're pretty sure it was no accident:
In a preliminary estimate, officials said about 143 million gallons of raw sewage spewed into the Tijuana River during a period of more than two weeks that ended Thursday.
“They basically said it was a bypass of raw sewage into the Tijuana River during the rehabilitation of a large sewer pipeline in Tijuana,” said Lori Kuczmanski, spokeswoman for the U.S. side of the commission, which oversees international water treaties with Mexico, among other things.
They sort of do things differently in Mexico. Here in the USA, containment booms and bypass pumps are required to perform work on a sewer line in a sensitive area. They seem to go for the "let it flow" method.