Yes, sewage water.
A utility company called Clean Water Services has been approved to give repurposed sewage water to a brewing company called Oregon Brew Crew. Based in (where else?) Portland, Oregon Brew Crew is a homebrew club, so the repurposed water will be provided for members brewing their own magic. In other words, it still might be awhile before you see sewer-beer in your local grocery store.
If this all sounds un-palatable, rest assured that, according to the Oregon Health Authority, the beer should be perfectly safe because of "the high quality of the treated water, additional microbial reduction in the brewing process, and a low health risk over all." Plus (happy Earth Day!) it will be eco-friendly; currently, it takes four liters of water to make one liter of beer; a little water recycling can go a long way.
We'll take a pint of sewer-beer over a can of Natty Ice any day.