Solar Panel Sorta Spin off: Does anyone have a cistern on their house?

my grandpa has one for his garden. that's all he uses to water.

those 275 gal plastic totes with the aluminum frames make great cisterns, have 2 of them at my camp. Put them on a platform so they will gravity drain, paint the plastic so algae won't grow

That with a small propane rv type hot water heater and we have all the water we need