Some homes off the sewage system deal with their sewage through a reed bed system. There is one on an organic estate near us, which I have seen. The water in the pond at the end of the system is clean enough to swim in, and employees do.
Since water from the shower goes into the same drains as water flushed down the loo - and that contains wee and much else, it is not unhygienic on that front.
There can be very little surface water on the planet that hasn't passed through many people - and animals and industrial processes, since the first amoeba made life in an ocean.