by Renee Roth, RainScape Designs
Greywater (also spelled greywater, grey water and graywater) is a unique source of residential waste water that is a great way to reduce your potable water use. Greywater is household water that is reused and recycled out to the landscape as a source of irrigation for plants. Household sources of greywater include: laundry, showers, bathtubs, and bathroom sinks. Simple systems like a laundry-to-landscape (L2L) do not require a permit.
The image above shows a simple greywater laundry-to-landscape set up, from Page 81 of The Water-Wise Home – How to Conserve, Capture and Reuse Water in Your Home and Landscape book by Laura Allen of Greywater Action
When Is a Permit NOT Required?
The State of CA revised the plumbing code so a construction permit is NOT required for a greywater clothes washer system in compliance with of Chapter 15 of the CA Plumbing Code, available here. The plumbing code has been revised and allows for greywater to be directed into mulched basins that supply water to plants. Below is information on greywater clothes washer systems (aka Laundry-to-Landscape, Ventura County GW-1 Guideline info is here). The Ventura County guidelines only discuss a “disposal system” using perforated pipe— which is NOT the best way to discharge greywater into the landscape (the perforated pipe gets clogged with roots and is difficult to clean.)
- A “greywater clothes washer system” is defined as a system utilizing only a single domestic clothes washing machine in a one or two family dwelling.
- The method for distribution cannot use a secondary pump and must rely on gravity.
- The amount of water from the washing machine is considered to be 15 gallons per person per day, e.g. 60 gallons per day for a 4 person household, but it gets complicated based on type of washing machine, soil type, size of drainage area etc. Consult with a trained landscaper familiar with installing greywater systems.
- Laundry soaps used must be biodegradable and non-toxic. They should also be low in salt (sodium) and boron (Borax) two common ingredients that are non-toxic to people, but harmful to plants and soil. Hydrogen peroxide bleaches should be used instead of chlorine bleaches.
In Ventura County, permits are required for all other greywater construction that alters plumbing pipes. For example, you will need a permit for a greywater system for outdoor irrigation if the system meets any of these conditions:
- Collects water from showers, sinks, or baths (for Ventura County residents, see – GW-2 sink and shower info here).;
- Alters the plumbing (i.e., whenever you cut into the drainage plumbing to access the greywater).
Ventura County Regulations
Greywater from washing machines directed into mulched basins does not require a permit in Ventura County, as long as the installer follows some standards developed by State of CA, and developed by the County of Ventura (see the GW-1 guidelines here). Greywater from bathroom sinks, tubs and showers can be redirected into mulched basins in your landscape (see GW-2 guidelines here). Reuse of greywater from kitchen sinks is currently prohibited.
You can talk to Ventura County Building Division at (805) 654-2771 during the design phase to prevent any plumbing or siting issues. Ventura County persons to contact via email:
- Guidelines for the Installation of Residential Laundry Graywater Disposal System (LGDS) (11″ x 17″) – GW-1
- Guidelines for the Installation of Residential Laundry Graywater Disposal System (LGDS) (18″ x 24″) – GW-1
- Greywater Systems for Residential Buildings GW-2
Information on Non Potable Rainwater Catchment Systems
- P14 – Non Potable Rainwater Catchment Systems 11″x17″
Santa Barbara and Santa Barbara County Greywater Guidelines
Both the City of Santa Barbara and the County of Santa Barbara have good guidelines for unpermitted greywater systems. They are both more permissive, and have good manuals and links to reusing both rainwater and greywater. See their resources below.
NEW Santa Barbara County Greywater Handbook and Website
- Greywater Action: Cofounded by Laura Allen, a non-profit dedicated to educating residents about greywater, its uses, and how people can use it to conserve water. Training classes are provided and upcoming Greywater Action events can be found here
- Graywater—A potential source of water: Article by Yorem Cohen from the UCLA Institute for the Environment (2009)
- California Greywater Guide to the California Greywater Code of 2010
- San Francisco Public Utilities Commission Greywater Design Manual for Outdoor Irrigation (2012)
- Conserving water with graywater system worth the effort, Ventura County Star article, November 2016
Visionaries /Leaders of GREYWATER and RAINWATER HARVESTING
Laura Allen’s Website Greywater Action http://greywateraction.org
Book:The Water-Wise Home by Laura Allen Storey Publishing 2015.
Greywater Green Landscape How to Install Simple Water-Saving Irrigation Systems in Your Yard by Laura Allen, Storey Publishing, 2017
Website of Art Ludwig, who started the greywater regulation revolution in Santa Barbara (1989) http://Oasisdesign.net AND Book: The New Create an Oasis with Greywater: Choosing Building and Using Greywater Systems. Art Ludwig, Oasis Design, 2006.
Brad Lancaster’s website www.harvestingrainwater.com AND Book: Rainwater Harvesting for Drylands and Beyond, Second Edition, Volume 1. Brad Lancaster, Rainsource Press, 20013.
San Francisco Graywater Design Manual for Outdoor Irrigation. http://sfwater.org/index.aspx?page=100
San Luis Obispo Guide to the use of Graywater http://www.mbnep.org/wp-content/uploads/2014/12/Graywater_08_20_09.pdf
City of Malibu, Ca – Graywater Resources http://www.malibucity.org/index.aspx?nid=752
Online Parts Info
CLEAN WATER Components
City of Thousand Oaks Parts List
City of Pasadena Greywater Video
Ask This Old House episode on greywater: https://www.thisoldhouse.com/how-to/how-to-install-graywater-irrigation-system
MOVIES TO LOOK FOR: Watershed Revolution, DAMNATION and WATERSHED: Exploring a New Water Ethic for a New West
SOAPS and Detergents
Hand soaps and shampoos by and large do not damage plants or clog soil profiles, in fact greywater is a light fertilizer. Laundry detergents commonly have sodium and boron which are chemicals that can have a negative effect on landscapes. The following are detergents or cleaners to avoid:
- Bleaches or softeners
- Detergents that advertise whitening, softening, and enzymatic powers
- Detergents with the following ingredients: boron, borax, chlorine, bleach, petroleum distillers, sodium and peroxygen
- Products designed to open clogs without scrubbing
- Water softeners that use sodium chloride
Common laundry soaps that do work (they are salt and boron free, and pH neutral) include Oasis, Ecos, Biopac liquid detergent, and Vaska. There are also soap alternatives that are greywater friendly, like soap nuts, and “wonder balls”.
Irrigation with Greywater
Trees and common edible plants can be used in a greywater system as long as no edible parts touch the actual greywater flow. The foods produced above ground from plants rooted in greywater are just as fit to eat as plants grown in drinking quality water. The water needs to flow into mulched basins to soak in. A picture of a mulched basin is included below.