I have a friend of mine who works for a muncipal water department. He told me that all waste water, whether it comes from the sink or toilet, is cleaned, purified, and returned to the water supply. Eventually, the same water will be used again, taken into the water system, treated and purified, and sent to our homes.
After all, where do they think the towns downstream from Ann Arbor Michigan get their water other than the same river into which Ann Arbor dumped their treated wastewater?
Everybody's downstream from somebody.