> remember that we all poop in the city water before they try to get it all back out and bleach it

Is there any place in the developed world that treats mixing sewage into your water source as a viable strategy of providing municipal water?

Yes, there have been standards for years already. It was proven in s US city some time ago when it faced a bad drought.

Las Vegas is a 100% closed loop system. All grey water is recycled back into Lake Mead fur reuse.

Modern sewage treatment is a modern miracle.