Sounds like you've thought about this more than me.
What about bubbling ozone through water to purify it?
I think houses should be habitable from -180° to 180° F. When I get the eco-modding bug out of my system I'll go back to working with low-cost energy-efficient and aerodynamic housing. (almost said sea-going semi-submersible geodesic domes) Had a career in that. I built houses, one town and one factory.