i have an oppertunity to buy this stainless tank for probably about $50 it's the 350-400 gallon tank. i was think about putting it in back of my house and filling it with rain water from down spouts from the house. i have a spot in the back of the garage where it wouldn't be very noticable. i live in town and cost of water is not a big issue for me but the flowers and hedges around the house don't seem to like the city water very much. is this just a bad idea? is this a whole lot of work for nothing??