Greywater: From Washing Machine to Garden
Like most American households, the average Southern California family uses about 500 gallons of water per day, according to the Los Angeles County Waterworks District. A significant portion of this often goes to watering lawns and ornamental plants.
Of course, planting native and drought resistant plants in place of grass is a huge step towards water conservation. But suppose you want to have your cake and eat it too (i.e. conserve water and grow water-loving plants)? Welcome to the world of greywater reuse.
Where Does Greywater Come From?
Greywater is water which you have already used for something in your home, but is not technically toxic. This might include water from your sinks, showers, dishwasher, and washing machine (though not the toilet).
How Greywater Reuse Helps
By diverting this “dirty” but non-toxic water to your yard, you're conserving valuable drinking water, preventing what is technically useful water from going through an inefficient wastewater processing system, and you're diverting a wasted resource to grow plants, and perhaps to grow food.
And it even helps the pocketbook. “Recycling water as greywater is good for the environment, and saves me money,” remarks L.A. River advocate and L.A. Creek Freak blogger Joe Linton. Linton built a DIY laundry-to-landscape system which directs water from the washing machine in his second story apartment to his garden.
According to Linton, such a system is simpler for beginners because the washing machine's pump helps divert water to the garden. Also, with a washing machine there is less worry about clogged pipes compared to, say, a kitchen sink, where you're dealing with food particles.
Anyone Can Do It
One might wonder about the difficulty and expense involved in diverting washing machine water to a yard. “Any handyman with basic plumbing skills can install it,” Linton assures. His system cost around $150 and is quite lengthy, descending from the second story and snaking through the yard to its outlet at the base of a row of blackberry bushes.
When you reuse greywater, your typical “eco-friendly” laundry detergents and other soaps may not make the cut. Some of these contain ingredients that are more eco-friendly than traditional detergents, but will kill your plants. Linton washes his clothes with a detergent specially formulated to be used in a greywater reuse system.
Such modification is illegal in some areas (especially in the Eastern states) and you should familiarize yourself with local laws before proceeding. In California, home plumbing modification for greywater reuse only became legal in 2009. It has been legal in arid Arizona since 2002.
But if there is any doubt about the safety of greywater reuse systems, Mr. Linton, at least, is confident. He enjoys the tree fruits grown from his greywater and attests that they are “yummy.” He does suggest that, for safety reasons, greywater not be used for root vegetables like potatoes or edible plants which grow near the soil, like lettuce.
Updated October 28, 2018.