[tomc1985]

Per cubic meter, sure, but there is a lot more of it than that to work with

We build our space equipment the same way... arrange for/synthesize/simulate a close analogue of an environment for initial development and then move on to the real thing once the initial quirks are solved. I certainly don't know the science behind water extraction but I imagine an extremely dry locale would not be the best place to be performing all your validation tests. Maybe start with a kind-of-dry desert, or some other biome. Like Joshua Tree instead of Death Valley...