Something that
@Aerindel said got me to thinking about when I was growing up. The place I lived received 3" of rain a year, when it rained it was like a holiday to stop and look up. But to keep a small garden like the one I have going still takes a lot of water. If I didn't have a river or a well could I collect enough water to make it work? Well if I had 12000 sq feet of collection area and a 10,000 gallon tank the answer is yes. If you needed to have water for your household, you would need to double that. When I visited Thomas Jefferson's Monticello I noticed that all the roofs directed the rain water to a set of cisterns that combined held about 12,000 gallons and the whole house complex was at an elevation above the garden area, so the house collected water for the house and the garden, but Virginia gets a lot more rain than where I grew up.
Flash forward, there would be no reason to create a flat surface of 24,000 square feet to provide water to a house and small garden, unless that surface also did something useful... This is my visualization of something reasonable, a small solar farm 150' X 160', setup on 8 rows 20' wide elevated to 12' off the ground by steel girders, at the bottom edge of each row of panels it a gutter going to a collection system which dumps in to a sentiment tank and then into one of 2 10,000 gallon fiberglass water tanks (1 at each end so the maximum gutter run in 75'). Now you have your rain water collection system, a solar farm, and a lightly shaded place under the structure where you could row garden, even using a small tractor. You could even use the girder structure to support over head zoned sprinklers.
Yep, if I won the lottery I would buy a bunch of property in the middle of no-where Nevada and build a place like that.....
But things being what they are, I will be happy making my garden work with the rain I get here.
