In any country, I would think.

Even where grey water systems are deployed for water re-use, shower water /is/ normally collected, but piss would be so diluted as to be a negligable contaminant. A shower uses roughly 70 litres of water. An average human bladder voiding is 400ml, so that works out at 0.57% piss in the grey water collected in a single shower. Negligable.

Piss away.

Source -Dr. I P Freely.

That’s not even what I’m criticizing. You said you’ve done pipe jobs, and it’s all pipes: you can only attest for where you have worked

And no, in some places water may be used very differently. Pee may contain a lot of unwanted chemicals, especially when the person is medicated