Cisterns can be problematic. In urban areas, water run-off will be heavily polluted so collection only from roof-tops would be feasible. Rain washes the atmosphere during its nucleation and on it's way down. How clean is today's urban rainwater?<quoted text>
Why not? A good idea.
But where do you then place the Solar Panels? Can rooftop run-off be compatible with Solar Installations?
In suburbs and even in rural areas water run-off can be polluted with chemical over-sprays. Again, rooftop collection only.
But, again, where do you then place the Solar Panels? Under the Wind Farms shading the ground-cover causing desert fields and dust storms?
A cistern for every 100 acre farm is reasonable but a cistern on every rooftop in America shortchanges the aquifers. This cheating of the groundwater sources also happens with Municipal Storm Sewer containment designs. Aquifer depletion is a big problem across the country and especially in the Southwest....
There are no free lunches.