We have four 50-gallon Rubbermaid water barrels -- the roof line that feeds them is pretty long so they fill up fast when it rains, but when they overfill the water runs into a drain pipe that goes to a ditch. DH came up with a system to hook the barrels together with PVC fittings, and dug the drain lines...
Since this photo was taken we've added one more tier of cement blocks so the barrels are higher up. To water the garden we use a submersible pump dropped down into a barrel -- DH keeps an eye on the water and the pump, while I direct the flow of water to the plants. There's probably a better system but we don't really need to do it all that often.
Love the idea of filling up bottles for watering the houseplants, we always end up "wasting" a lot of the rainwater at the end of the season!
