Many commenters are ...

Many commenters are expressing a lot of unfounded angst, mainly from their inexperience. Actually grey water and other water reuse have been practiced for many years safely. Wastewater is 100% recyclable. Quality standards and appropriate treatment based upon end use are well established. We are not running out of water. We are running out of free or wasted or cheap water in some locations where population demands are overtaxing local natural supplies. Of course, the first principle is to reduce wasteful use.  Apart from conservation, which has limits, proper reuse of all types, including potable reuse, is the best opportunity for quantity, reliability and sustainability. The experienced and creative engineers, not the amateurs,  know how to do it.  The public needs to be informed with facts so they can support the recycling efforts. WHO has new direct and indirect potable Reuse  Guidelines coming out this summer. It already has published other water use guidelines.