Water harvesting/storage

Got about 500L. collecting from house roof that fill up quickly when get any amount or rain so use these first. and 400L from a greenhouse. I don't use growbags now or pots except for starting plant off so everything in ground when warm enough. The house ones were getting low but all are pretty much full now.
It is very rare for all to empty (always keep 1/2 a butt for acid lovers) but occasionally have had to fill the 2 near the house. Not sure if I have needed to since I added the ones for the greenhouse.