I capture rain off my roof into buckets and trash cans and whatever container laying around. Even use a wheelbarrow at strategic drip corners. I only water my jaboticaba with rain water as anything else, especially well water will degrade the plant. City water with flouride and chlorine can kill back as well. Especially flouride in certain ornamentals. Palms are pretty tolerant though, but yes, rain water the best.

I also have a pond that captures water off the roof. That is all kinds of tadpoles and debris in it. That has to provide plant nutrients as well as I bucket the water out of it and onto plant roots.