Greywater use in your landscape

Using Greywater in your landscape

by Barbara Wishingrad

Greywater (or graywater) is any water that has been used in a home except toilet water, which is called black water.  This includes water that drains from washing machines, sinks, showers and tubs.  Kitchen sink and dishwasher water is sometimes called dark grey water, as it may contain grease and food particles, which can cause clogging and slow infiltration into the soil. 

The easiest way to direct greywater into your yard is from the washing machine, with the Laundry to Landscape system.  In 2009, California passed a new regulation providing for installation of laundry to landscape systems in residences without the need for a permit, as long as certain conditions are met. These conditions are perfect for sending the water to fruit trees.

Art Ludwig's diagram of a laundry to landscape systemthe design needs to include a way to direct water to the landscape or the sewerHDPE is used to carry the greywater to the fruit trees

 

Greywater needs to be kept on the site where it was generated, sent to the landscape or to a disposal field, and buried under at least 2” of mulch, rock, or soil; a solid shield may also cover the release point. No ponding, spraying, or exposed runoff of greywater is allowed. Root crops and the edible portions of food crops are not allowed to be irrigated with greywater.

Fruit trees thrive best when planted in a basin that is covered with mulch, so they are a perfect outlet for greywater discharge.  Some species especially respond to greywater, such as the tree affectionately called the Santa Barbara Greywater Banana. 

banana and passion fruit thriving on greywateroutlets for greywater getting set up in the landscape

The type of washer you have and the amount of laundry you typically do in a week will determine how much greywater will be available and which trees, and how many, should get the greywater.

Plant friendly products are key when reusing greywater.  All products need to be biodegradable and non-toxic. They also should be free of salt (sodium), boron (borax), and Chorine bleach.  A Laundry to Landscape system requires that a mechanism is provided to direct the flow of washer waste water either to the landscape or the sewer, so that if you choose to use one of the products that aren’t healthy for the soil and the trees, you can send that load’s waste water to the sewer. Thedirection control of the greywater needs to be clearly labeled and readily accessible.

Greywater from a washer provides a regular source of watering trees that does not depend on the weather, and is great for busy people who don’t have the time to pay attention to irrigating. 

Simple occasional maintenance is needed for greywater systems to make sure that lint or other particles are not clogging the lines, that all components are functioning well, and that each tree is getting enough but not too much water.