All the water used by a household is potable. Only a tiny percentage needs to be, it is senseless to flush a toilet or water a lawn with drinking water. It is not easy to ventilate the entire house. American houses are waaaaaaay larger than they need to be. Every bit of water used in the house is treated like raw sewage.
All water produced by a household is sewage, wheras only a small fraction needs to be.
Yet despite rising costs and environmental issues associated with its use, more than 90 percent of residential construction in this country today is wood-frame construction. Perhaps there is increasing hope for some of the alternative housing designs. Here is a EarthShip link, with links to lots of other Earthship resources. In fact, I may try to start one myself in a couple of years if no one else beats me to it. I have a few ideas for doing this.