Rain Barrels Water Conservation in your own backyard! 

A rainbarrel is a system that collects and stores rainwater from your roof that would otherwise be lost to runoff and diverted to storm drains and streams.  Usually a rain barrel is composed of a 55 gallon barrel, hose, PVC Couplings and a screen to keep debris and insects out. A rain barrel is relatively simple and inexpensive to contract and can sit conveniently under a down spout. 
Lawn & garden watering may take up to 40% of total household water use during the summer.  A rain barrel collects water and stores it for when you need to water plants. According to EPA a rain barrel can potentially save most homeowners about 1,300 gallons of water during peak summer months.   
See the pdf file below for a brief demonstration on one way to make your own rain barrel. 
There are also many ideas for rain barrels online.