Researchers in Canada have made a discovery you may not want to think about the next time you go swimming.

They have figured out how to test the amount of urine contained in swimming pool water.

In one test, the researchers estimated that a pool contained about 75 litres of pee.

But the good news - if you can call it that - is that this amounts to just 0.01% of the total volume of the pool.

The scientists from the University of Alberta analysed more than 250 samples from 31 pools and hot tubs in two unnamed Canadian cities. 

They came up with the estimate by testing for a common sweetener (ACE) which passes through the body in urine. 

The researchers say 19% of adults admit to relieving themselves in a pool at least once in their lives.