Are you one of those people who keeps their mouth shut while swimming because you worry how much urine is in the pool?
Well, probably best you don't read this.
A study in Canada has mapped out precisely how much urine we secrete into our swimming facilities - and found that up to three litres of pee are released into large pools every day.
Over the course of three weeks, scientists from the University of Alberta tracked the concentration of an artificial sweetener called acesulfame potassium, which passes through the body unaltered, in the waters of two local swimming pools.
By the end of the three weeks, researchers found that roughly 75 litres of urine had been secreted into the larger pool (roughly one-third of the size of an Olympic venue) and 30 litres into the second, smaller facility.
Alarmingly, the results suggested this total was 'topped up' every day.
So next time you're in the pool, be sure to keep your mouth closed. And, if you're caught short, get out and go to the changing rooms, you filthy animals.