The typical American household sends the water it’s bathed, brushed its teeth, and cleaned its clothes with, called graywater, to the municipal waste facility. Then it waters its lawns and gardens with more fresh water, wasting about 1,000 gallons per month. But you can safely use graywater for irrigation if it’s handled by a proper recycling system, and if you use biodegradable detergent and don’t wash diapers.

As an avid gardener living in dry California, I wanted a simple and inexpensive way to reuse water to keep my garden green and healthy. In 2004, my wife and I had to retrofit our house’s basement, so I moved the laundry machines to the back carport, which is at a slightly higher elevation than our adjacent garden and far from a sewer connection. This was my opportunity. At first, I simply let waste water from the washer run into a 3" flexible corrugated pipe, which I moved around to drain near any plants that I wanted to water. Later, after we decided not to move the machines back inside, I built this more permanent underground system.