Guess what? People are generally disgusting, as detailed by a Daily Mail article about public pools:
A shocking new survey claims that a full 20 per cent of those swimming and splashing about also relieve themselves in it.
Furthermore, red-eyes that often associated with a day at the pool are from chloramine, the chemical created when urine combines with the chlorine that's already in the pool, not from the water treatment chemical.
While it did not exhaustively look into the reasons behind why people think they can urinate in a public pool, the survey suggests that it is easy and anonymous.
Oh, there's more:
The report says that the famous ‘pool smell’ results not from the chlorine, but from the slurry of water impurities swimmers bring in by not showering reacting with the pool’s chemicals.
That is to say, the more strong-smelling a pool is, the more contaminated it is as well.
The Council notes that a well-maintained pool with the proper pH balance has no discernible odour.