Our rainwater harvesting tank is not a thing of beauty (especially from the perspective our neighbours) but it is doing a great job and I am so glad we got it up and connected while it is still the rainy season. It simply take the rain off the polytunnel roof and stores it. So far its about a third full after a month. It will hold a staggering 54 cubic meters of water which should be enough to water the entire polytunnel, when full, and warm, for a month. It just seems criminal to use mains water when the stuff comes out of the sky for free. Oh, and our field has a tendancy to flood so any water that doesnt land on the ground is good!
It looks so big for our current needs that I was beginning to wonder if I had got my sums right but a very nice irrigation guy I have been talking to seems to agree it will the right size of a full scale operation.