A few weeks ago we noticed that when it rained, the water was running off the roof of a neighbouring building and falling into our garden in a kind of waterfall. We decided to make use of this free water supply by making a very simple rainwater harvester. We had an old wheelie bin in our yard that we don't use anymore, so we put it in the garden and put a plastic liner inside it - the sort that you might put in a pond. Then we positioned it in the garden under the waterfall. It is already doing it's job very well and is slowly filling up with water every time it rains! You can see a picture of it below.