Re-nest reader conflictedthimble had this to say about the program and the Earthships in general:
They use rainwater as their primary water source, and solar as their electricity. They are essentially off the grid. The best part? They still use lights, internet, cable, etc! I mean, it's extreme, but not so much that i didn't seriously consider it! I lived in phoenix for a few years, so this didn't seem like much of a stretch at all...
We missed this episode of HGTV's Extreme Living, but we've been enjoying the quick slideshow of images -- and, for anyone still interested in Earthships, here's a video on the topic from CNN:
(Conflictedthimble, thanks for the tip!)