[aShepard]

Of course, the article doen’t mention the obvious: a dual plumbing system in each house/apartment.

Shower drains and bathroom sink drains that go into a tank, to be routed to the toilet system when needed to flush.

This relatively clean “gray water” could easily give double service.

[alwaysconservative]

Campers and motorhomes use gray water for that very purpose, and it is a huge water saver.

[jwh_Denver]

And clean the damn turlet at the same time!