Nature knows no waste. Humans? Think of all that perfectly good water that flows down the sewer out of our laundry machines. Why not harness that laundry water to grow food? Of all the projects I’ve attempted on our modest urban homestead, reusing our laundry greywater was one of the simplest. In this post, you’ll learn how to reuse laundry greywater. I’ll share a useful greywater resource and describe the systems I installed at my house and the house of a neighbor.
Before heading to the hardware store for plumbing parts, you’ve got to answer two questions: “How much laundry does my household do in a week?” and “Where am I going to send that water?” For me, in both of the installations I describe, the answer was to send the laundry greywater to fruit trees. For food safety reasons, vegetables are not a good destination for greywater. Fruit trees, on the other hand, thrive with greywater. If you’ve got a big household and a lot of laundry, plant some more fruit trees. Fruit trees can be pruned to keep them compact, so you don’t need much space to create your own mini-orchard.
Greywater expert and author Art Ludwig has detailed an easy to understand free plans you can find on the laundry to landscape section of his website Oasis Designs. These are the plans I used to install the laundry to landscape system at a neighbor’s house several years ago, which have transformed a hot and dry side yard into a lush landscape of fruit trees and native plants.
Ludwig’s laundry to landscape system is simple. You send the drain hose of the washing machine to a three-way diverter valve (Ludwig sells a nice brass one on his website). This allows you the choice to send the water back to the sewer in the wintertime, if it’s raining outside, or if you’re doing a load with bleach or diapers. While the diverter valve is expensive at around $50, it’s well worth it for the convenience of being able to easily shift between landscape and sewer.
From the diverter valve, one set of 1-inch pipes leads to the sewer and the other leads to the landscape. On the side that runs to the landscape, Ludwig recommends installing a backflow preventer (some laundry machines can suck water back, and you don’t want that to happen). You also need to install a vent, and means to hook up a hose to clear the line of lint. See Ludwig’s plan for details.
Once the line is out in the landscape, you have the option of sending all the water to one place or creating a sort of pressurized drip system by punching holes in the pipe. Ludwig created a spreadsheet that details the size and number of the holes you can punch in the pipe. At my neighbor’s house, there are around ten holes in the pipe that irrigate a line of fruit trees and flowering shrubs.
You can use either PVC pipe or flexible HDPE pipe. PVC is a bit of a chemical nightmare, but it’s what I went with since I couldn’t find HDPE line in less than huge quantities in my area. Note that you must use pipe that is 1-inch or greater. Do not try to hook a laundry machine directly to a garden hose. Doing so will burn out your laundry machine’s pump.
I’m still using an earlier Ludwig design at my home. Rather than sending a pipe directly into the yard, my washing machine greywater discharges into a 55 gallon drum. I have a standard garden hose hooked up to the bottom of the drum that I drag around the yard. The advantage to this design is that I have more flexibility in where I can send the water. The disadvantages? You need gravity to do this (my house is on a hill). And the garden hose plugs up with lint frequently. Ludwig no longer recommends this configuration, but it has worked well for me.
- You need to use a detergent formulated for greywater use. Note that many “eco” detergents have ingredients (like boron and borax) that are toxic to terrestrial plants. I’ve been using Oasis Biocompatible that I order from Amazon. You can also use soap nuts.
- If you have absent-minded members of your household who might send a load of bleach out to your orchard you should consider a lock on the three-way diverter.
- Nobody has ever gotten sick from greywater in the US. That being said, you should avoid loads with diapers. And don’t use greywater for vegetables or lawns.
- Never store greywater. It goes rancid really quickly. Send it straight out to the garden. The valve on the bottom of my greywater tank is never closed.
- Keep it simple. Avoid the expense and maintenance duties of pumps and filters. They aren’t needed.
- I’m in balmy Los Angeles. If you’re in a place where it freezes, you will need to drain the outdoor lines and/or bury lines beneath the frost line.
- Send greywater out to mulch basins. The mulch will help filter and soak up excess water.
- Since washing machines pump out their water, you can force the discharge uphill to some extent. But be careful. Go uphill too much and you risk burning out the washing machine’s pump. According to Ludwig you can “irrigate any distance downhill, or pump up to an elevation 2’ below the top of the washer 100’ away.”
Laws in the US regarding greywater vary widely. Some states allow laundry to landscape without a permit and others treat greywater as sewage. Ludwig has a state by state listing of greywater laws. If there’s any risk that authorities might bust your greywater party, install the system after building inspectors have left and be discreet. Our system was illegal until 2009, when California amended the plumbing code to allow laundry to landscape without a permit, and nobody noticed or cared.
Have you installed a laundry to landscape system? How has it worked for you? Have you worked with other greywater sources such as your shower or kitchen sink?