a lot of people use public swimming pools (be it on a hotel, sports centre, gym, etc. A pool is visited by many people on a single day. It is quite likely that a few people end up urinating in the pool. That can’t be clean! I mean, it probably happens at least once a day. Make it way more on really busy places! So… on average, how much of a swimming pool is actually yellow, warm pee?
I don’t know the exact percentage, but it’s probably fairly low given the large size of most public swimming pools… and remember there is filtration going on much of the time. I don’t think peeing is as bad as say defecating or vomiting in a pool. I was taught at some point that urine in a normal person is fairly sterile.
Most residential pools hold 15k to 20k gallons. Most commercial pools are quite a bit larger, but of course hold more people. Assume a 25k gallon pool. An average “tinkle” is probably about 0.066 gallons (based on looking it up and converting from millilitres). Even if you assume 10 people per hour, that would add up to only 0.0003 percent. And chlorine is quite effective at neutralizing urine. It would take a lot of people emptying their bladders all at once to become a problem.
Let’s work it out. An Olympic-sized swimming pool has a volume of approximately 2,500 cubic meters, or 2.5 million liters. A swimming pool in most of the US will probably only be open for about 100 days per season, after which it’ll be drained and cleaned. If we assume that one person pees in the pool every day, and that each peeing has a volume of 1 liter, then pee will end up being 1 part in 25,000 in the water. If peeing happens less frequently, or the volume per pee is lower, or if urine breaks down or is filtered out over time (all reasonable assumptions), it’ll be even more diluted.
And remember when you swim in a lake, stream or the ocean you are already swimming in a place full of pee and poop with no filtration or chlorine. 
And keep in mind that urine is mostly water anyway.
Not that that’s an excuse.
Poop too, sometimes. Taco Bell anyone?
Probably about the same as in your public water supply. Birds fly over the reservoir and shit.
Whatever you do, don’t think about how everyone in the pool is rinsing their anus in the pool water.
Nobody can pee i liter all at once. Also i doubt that pools are drained every winter. We didn’t our home pool in Maine though it was used less than 90 days out of the year.
You mean you think whales pee in the ocean? Damn them.
A homeopath’s nightmare.
100%, considered over a long enough time.
but how efficient are the filtration systems? I mean, if they worked that well we could pee through life straws and go with no water for ages!
Polar Water is more my speed.
I will take that challenge and beat it (I have filled a 32 oz Gatorade container more times than I can count and run out of room at the end). 1 liter is about 33 ounces. Of course, that is a side point, most people do not pee anywhere near a liter but a few people can. Say what you want about me but I want to be remembered for both my peeing for distance and volume records because my other talents just aren’t cutting it. If extreme peeing was an Olympic sport (and it really should be), I could help bring another gold medal to the US team.
The problem with this question is how do you define “urine”? It is a solution after all with varying degrees of concentration of various components, the most significant one by far is water itself. Almost all sources of water, including tap water have urine in them to some (very small) degree. The same thing is true with a swimming pool. You can argue that any time someone pees in it, the whole pool (or lake) just becomes really watered down urine. You have to do a chemical analysis of the water to find the concentration of the components that you think are undesirable. Most of them aren’t in small quantities. As noted, urine is sterile when it leaves a healthy body and tends to stay that way in a diluted and chlorinated environment. The ratio of the volume of water in a typical pool versus potential urine output is trivial and almost always harmless. The chemicals dumped into a pool to keep it stable and clean overwhelm the urinary output of any reasonable number of people.
This looks like the ultimate Fermi problem to me.
It is not so much the filtration systems as it is the chlorine oxidizing the organic compounds.
What, exactly, is in urine that you don’t want to touch, or drink, for that matter? I think it is, medically speaking, a pretty harmless substance, free of any toxins or pathogens…
Urine is sterile enough that people drink it unfiltered but the majority of our water loss does not come from pee but from breathing.