Swimmers in an Olympic-sized pool could be surrounded by up to 50 gallons of urine, a new study has revealed.

Scientists used an artificial sweetener found in urine to measure how much pee is in swimming pool water.

They discovered the sweetener acesulfame potassium (ACE), is consistently present in urine, making it easy to monitor pool levels.

In tests they found a 91,500 gallon pool contained 5.8 gallons of urine and a 183,000 gallon pool, a third the size of an Olympic pool, was awash with around 17 gallons.