I have dreamt about buying some cheap land in the desert and building a giant sealed dome. In theory once "charged" with water, you shouldn't need any more water input, as long as you can condense it out of the air. I imaging a bunch of solar panels outside so I can run A/C or underground heatpump to moderate the temp and "make it rain". Then you can grow some food in there as well and "recycle" your waste products. I doubt I could be fully self-sufficient since a large enough dome would be prohibitively expensive, but would be a pretty cool way to live I think.