In the United States, the average person uses about 40 gallons of water per day to bathe, wash dishes and clean clothes. Unfortunately, this water almost always goes straight down the drain. But this “greywater” could be put to good use to irrigate fruit trees and other plants. Greywater refers to all used household water except water from toilets, which is called “blackwater.” Historically, state laws have dealt with water from your sink, shower or washing machine in exactly the same way as water from the toilet — it’s all considered sewage that requires treatment. Consequently, home systems that use greywater for irrigation are sometimes illegal.
However, in recent years, greywater activists have been working to change this attitude and the state codes that enforce it. Now, with more than half of U.S. states facing water shortages and the momentum shifting as some states change their codes, we think greywater reuse is coming into the mainstream. Many policymakers are beginning to see greywater as a valuable resource that — with a few simple precautions — can be safely reused in home landscapes.
For decades, greywater has been a boon to gardeners in dry climates, but using greywater has many other benefits in all regions. Greywater use lowers your water bill, and diverting greywater from overloaded or failing septic systems can extend their life. Reusing water saves energy: Greywater irrigation replaces water that would otherwise be treated to drinking water quality, and it also isn’t treated at the sewage treatment plant, saving more energy. And perhaps most importantly, more efficient water use reduces pressure on scarce water resources — especially in the drier parts of the country, where farmers, individual households and wildlife all face the problem of limited water supplies.
A Simple Laundry-to-Landscape System
The simplest type of greywater use is to collect water in a dishpan as you handwash dishes, and then toss it over your flowerbeds or fruit trees. This is a wonderfully simple, inexpensive way to tap into greywater, but with just a little more effort and expense, you can capture much more water.
One of the easiest and most popular greywater systems is a landscape-direct system that diverts greywater from your washing machine and routes it to mulch basins around trees or bushes. This “laundry-to-landscape” system captures greywater from the drain hose of the washing machine and sends it out to your plants through 1-inch tubing, without the need to alter existing plumbing. You can expect to harvest 10 to 25 gallons of water per load for a horizontal-axis machine, or about 40 gallons per load for a vertical axis machine.