This is a duplicate of an earlier discussion: <a href="https://news.ycombinator.com/item?id=17166132" rel="nofollow">https://news.ycombinator.com/item?id=17166132</a>
> It is also planning a pilot to help tenants reuse so-called grey water - the water from bathroom sinks, showers, baths and washing machines.<p>So two different sewer systems?