NEWS YOU CAN USE: Pee plus chlorine yields a chemical warfare agent.

[W]e need [an olympic-sized] pool that is two parts water to one part chlorine and would probably burn the eyeballs out of your sockets and make your skin peel away from your bones (this calls for a pool boy who can only be criminally sadistic). If you and three million other people could get at this pool and unload your pee into it before your bodies melted, before the crowd crushed you to death, and before you drowned from the massive tidal wave of pee... yes, you could feasibly die of cyanogen chloride poisoning originating from chlorinated water and pee.

So it's probably safe to swim in yellowed water.