Vicki, I did a search on our site, but could only come up with one thread with the word "diverter" in it, and it didn't apply to your problem. So, I'm thinking if you re-post your question under one of the Organic Gardening Sections, maybe Permaculture, you may get a better response. Oh, and for us USA dummies, maybe put "water b-u-t-t/rain barrel", just to be clear.

I think that term (rain barrel) is more common over here. Just a suggestion...
But while we're on the subject: I have aluminum gutters and downspouts on the house, and have put rain barrels under a couple. All I did was cut the downspout to the desired height and reattach the elbow from the bottom. If I wanted to move the rain barrels, I'd have to get a new length or two of aluminum downspout to replace the old, or attach to reach grade, and then reattach the elbow. Any other system I don't know, so, that's the end of my suggestion!