Graywater Systems

greywater systems can be simple or sophisticated. In its simplest form, greywater collection is a bucket under the sink to catch water for reuse in your landscape. That water could be used for trees and shrubs, but really shouldn’t be used on edible plants.
A slightly more sophisticated system is a barrel or drum for collecting water for your garden from a downspout or gutter. A 50-gallon drum connected to a downspout can supplement the needs of general landscape irrigation.

And an example of a more sophisticated system is the one employed at the Wampanoag Tribal Center (similar to the illustration shown here). It takes water used in the kitchen and at hand washing stations and treats it in non-edible plant beds in the building.
Check out http://www.harvestingrainwater.com for more information.