At the other end of the spectrum from raw water is "poop water"—sewage effluent that has been transformed back into safe drinking water. Whereas raw water is completely untreated, poop water—or "direct potable re-use" if you want a more palatable euphemism—is very highly treated, for obvious reasons.

Drinking reclaimed sewage water is hardly a new idea; in fact, if you live downstream from an urban area, you may already be doing so to some degree. A few years ago, Bill Gates drank reclaimed water publicly and repeatedly —even on national TV with Jimmy Fallon  —to promote a company developing treatment plants for developing countries. A couple of years before that, the film Last Call at the Oasis featured Jack Black drinking the stuff.

For the most part, the movement to reclaim sewage effluent for drinking water stays under the radar, since the biggest barrier to widespread adoption is negative public perception—the "yuck" factor. Whoever first coined the phrase "toilet to tap" to describe the practice certainly didn't help the campaign. 

But every now and then, the idea gets fresh press. In 2017, Ireland's national water utility included reclaimed water as one source of supply in its next-25-year National Water Resources Plan. Closer to home, Arizona has recently moved toward legalizing use of reclaimed effluent. And California is finding that the public has become more accepting of the idea as the state's water problems have worsened.  

So, like it or not, water formerly known as sewage may be coming soon to a faucet near you. Raw water, poop water, or something in between—who knew there were so many ways to enjoy your favorite beverage, H2O?