I live in South Africa where water is very scarce and we have to be able to use it to its maximum. This is why I am aware of the importance of home rainwater collection.
In the town we lived in until recently empty, dry taps in the middle of the day was not an unusual thing. So, if you wanted to do gardening you had to be prepared with stored rainwater, not to mention the water you need to flush the toilet!
In those circumstances home rainwater collection was vitally important. It was very important to make sure you plan your system in such a way that you get the maximum water from every drop of rain that fell.
What is more, we are not rich so we had to make very sure that our system was planned optimally to save costs. We were fortunate to have the expertise right there because it was a farming community, otherwise we would have had to do some research to make sure we plan our home rainwater collection correctly.
You will be surprised at how much water you can collect from relatively little rain. It can make you completely independent of any water supply source for your gardening purposes. That was such a relief to us as we love our vegetable garden. I cannot imagine having to survive without fresh lettuce and herbs in the garden. Even now, while we are living in a town house complex, we have our lettuce and herbs in pots on the patio!
So, I think considering home rainwater collection is a very good idea for everyone that loves gardening.