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

Edit: In cities in western countries of course most of the time it’s all going to the same place. But I don’t think that’s why it’s taboo to pee in the shower. It’s because it’s seen as unhealthy for the other people using the shower / bathtub