Graywater Resources | Santa Clara Valley Water
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This graywater resources webpage provides a graywater introduction, how-to videos, resources on finding equipment and installers, soap and plant health, and more. Click here for an example system and parts list [PDF]. Additional details and equipment can be found below.

Frequently Asked Questions

Graywater Frequently Asked Questions

Overview

  • Click here for Frequently Asked Graywater Questions [PDF] including what’s graywater, when you may need a permit, and how much water you may save, among other questions.
     
  • How do you spell graywater? FUN FACT: "Graywater" can also be referred to as "greywater", "grey water", and "gray water". Government agencies tend to spell graywater with an "a" while nonprofit organizations tend to spell greywater with an "e". 
     
  • What about my water softener? If you have a water softener, consider using a potassium-based water softener instead of sodium-based, bypassing the clothes washer from the softened water, or trying alternatives to conventional ion-exchange water softeners [PDF and study evaluating water-softener alternatives]. 
     
  • Where can I find information on recycled water and rainwater systems? Valleywater.org has for information on recycled water elsewhere. Click here for rainwater system information like rain barrels and more. Graywater has different requirements and benefits than recycled water or rainwater systems.

Plants and Soaps

  • Is graywater safe for my landscape? Yes, most plants are healthy under long-term graywater irrigation (Sharvelle, S. et al. 2012. Long-Term Study on Landscape Irrigation Using Household Graywater - Experimental Study Water Environment Research Foundation; Alfiya, Y. et al. 2012. Potential Impacts of On-Site Greywater Reuse in Landscape Irrigation. Water Science & Technology, 65.4, pp.757-764.).

    With that said, graywater is better for certain plants compared to others. In general, trees, shrubs, vines, California-native riparian plants, and hardier native plants perform well. Maintaining a healthy soil, choosing the correct detergents, and using best practices for designing, installing, and maintaining your system are key to keeping your landscape healthy. Knowing the signs of stress from sodium- and boron-accumulation can help resolve symptoms before a problem becomes pervasive.

    In general: yes, graywater is safe for your landscape.

  • Can I use graywater to grow vegetables? Graywater can be used safely with fruit trees or berry bushes. Never use graywater to irrigate fruits or vegetables that come in direct  contact with graywater or the soil surface, such root vegetables like potatoes or carrots.

  • How many plants can you irrigate with a Graywater Laundry to Landscape System? This will depend on how frequently you do laundry, the type of clothes washer you have, the climate near your home, and the types of plants you’re irrigating. For a rough estimate, 
    • a front-loading clothes washer can provide water for 1 tree for every load per week and up to 8 outlets overall. Whereas, 

    • a top-loading clothes washer can provide water for 2-3 trees for every load per week and up to 12 outlets overall.

    • To help calculate the specific gallons of graywater needed based on a plant’s size, see Table 1 in this PDF (University of California Division of Agriculture and Natural Resources).

System Types

  • What is a Graywater Laundry to Landscape System? The only graywater system for which the District provides a rebate, these sustainable, cost-effective systems redirect water from your clothes washer to your landscape without additional pumps or filters or permits*. The resources below focus on graywater laundry-to-landscape systems, but you will also find useful information for other graywater systems as well.
    *See "Legal Requirements" below for additional information.

  • When are Graywater Laundry to Landscape Systems most appropriate? 

    • The clothes washer is accessible, near an exterior wall, or above a crawl space;

    • The landscape’s first graywater outlet is around 50 feet or less from the clothes washer;

    • The landscape is level or downhill from the clothes washer; and

    • The plants you want to prioritize with graywater irrigation are decorative trees, fruit trees, shrubs, groups of smaller herbaceous plants, or establishing drought-tolerant plants. 

  • What about Whole-House Graywater Systems? (No rebate) Click here for an overview on types of whole-house graywater systems, general information on codes and costs, system maintenance considerations, and more (Alliance for Water Efficiency). For information on equipment for these non-rebate graywater systems that will require a permit, see below (Greywater Action):

Videos for those New to Graywater

Graywater Overview Videos, New to Graywater Videos

The videos below walk you through a completed Graywater Laundry to Landscape System that received a rebate, quick introductions to graywater systems, and tips on how to safely use graywater:

How-To Videos: Ready for Graywater

Ready for Graywater Videos, How-To Videos, Instructional Videos

The videos below contain a step-by-step guide to install a Graywater Laundry to Landscape System that would qualify for the rebate program, how to get past cement walkways or patios, and a presentation to help design and install a Graywater Laundry to Landscape System.

Instructional Videos

Equipment Information

Graywater Equipment Information

  • Essential components include:
     
    • Full-Port Diverter (3-way) Ball Valves (This should have the same diameter as the clothes washer's drain hose, typically 1-inch diameter.)
       
    • Auto Vent (or comparable equipment such as Air-Admittance Valves or In-Line Vents)
       
    • HDPE (High-Density Polyethylene or poly-tubing), quick-connect or locking PVC, and/or PVC (Schedule 40). Most projects require fewer than 100-feet of tubing/PVC.
       
    • An example parts list, including how many you may need is provided on the Rebate Requirements page. Additional, fewer, or slightly different components may work better for your project.
       
  • Where to find equipment?
     
  • The District's Landscape Resources includes lists of local irrigation supply stores, nurseries, and landscape professionals that may be able to provide additional assistance.
     
  • What about tools? Check out the PG&E Tool Lending Library. Hardware stores and some libraries also offer tool-rental or tool-lending services.

Finding Installers and Installation Help

Graywater Installer and Installation Help

  • Graywater Installer Directory
     
  • Green Gardeners may have sufficient knowledge to assist completing your graywater project.
     
  • Green Plumbers are familiar with water- and energy-saving technology and techniques. Under “Additional Services I May Require*” select “Grey Water” to find plumbers to help with your project.
     
  • Find a Licensed Contractor (Department of Consumer Affairs). To find a licensed contractor that may have the skills needed for your graywater project, under the "License Classification" drop-down menu select either "C27 - Landscaping Contractor" or "C36 - Plumbing Contractor". Other classifications may be able to help you on your project as well.
     
  • ReScape California has lists of Bay-Friendly Qualified Professionals that have been trained in sustainable, holistic approaches to landscape design and maintenance, and tips for how to hire a landscape professional.
     
  • Additional lists of landscape professionals can be found here.

Soap and Detergent Information

Graywater Soap and Detergent Information

To minimize effects on soil pH and salinity, liquid soaps/detergents are preferable to powdered soaps/detergents in general. More specific information is provided below:

  • Key Tips for finding specific graywater-friendly soaps from Greywater Action's experience and expertise.
     
  • General Information for help finding graywater-compatible or garden-friendly detergents when product labels aren't sufficient. Other graywater resources not included on this webpage are also available on that website.
     
  • Garden-Friendly and Environmentally-Friendly Detergents* to determine if the detergents you already use may be garden-friendly (EPA's Safer Choice Program). Importantly, “environmentally-friendly” does not always mean it will be garden-friendly. 
    *When searching, look in the “Search Products” area and select any of the “Laundry Product” options under the Product Type (Optional) drop-down menu.
     
  • Chemicals to avoid:
     
    • Salts and Boron
       
    • Chlorine Bleach
       
    • Petroleum distillate
       
    • Antibacterial compounds
       
    • Whiteners, softeners, enzymes, paraben compounds
       
    • 1,4-dioxane (This may be found in certain detergents identifiable by the prefix, word, or syllables "PEG", "Polyethylene", "Polyethylene glycol", or "Polyoxyethylene", and may be a byproduct of sodium laureth sulfate.)
       
    • To find the specific ingredients in your preferred detergent, click here (US Department of Health & Human Services' Household Products Database). Use your computer's search function or scroll through the page to find your detergent, click on it, and check to see if it lacks the chemicals to avoid listed above.

Since soaps and detergents contain a variety of chemicals to aid in cleaning, inquire with the County’s Department of Environmental Health, the California Department of Food and Agriculture, and University of California Division of Agriculture and Natural Resources for additional information if you choose to use graywater on food you may eat and you are unsure of the soaps or detergents in your graywater. To minimize potential health and safety concerns, look for “graywater-compatible”, “garden-friendly”, and “dioxane-free” detergent labels.

Mulch Basins and Soil Health

Graywater Mulch Basins and Soil Health

  • Learn about different types of mulch to place in your graywater system's mulch basins (Review the How-To Videos above for examples of mulch basins). Mulch basins can be trenches, circular, or any shape needed to spread the graywater to sufficiently infiltrate the soil. A Graywater Laundry to Landscape System tends to have a total of:
     
    • Up to 8 mulch basins for a front-loading clothes washer, or
       
    • Up to 12 mulch basins for a top-loading clothes washer. 
       
  • Improve the health and structure of your soil to improve your graywater system's performance and the health of your landscape.

Other Technical and Design-Assistance Resources

Graywater Other Technical and Design Resources

Legal Requirements

Graywater Laundry to Landscape Plumbing Code Legal Requirements

California Plumbing Code: Chapter 15 describes graywater system requirements [PDF]. Check with your local building or permitting department for additional rules to consider when planning your project. An overview of legal Laundry to Landscape systems is provided in Section 1502.1.1 (pages 353 and 354 of the linked PDF, or pages 310 and 311 of the printed version, and summarized below).

Please note, some of the requirements below are already reflected in the rebate program's Rebate Requirements. This list is provided for your reference:

  1. If required, notification has been provided to the enforcing agency (relevant Building or Planning Department) regarding the proposed location and installation of a graywater irrigation or disposal system. Click here for Building Department contact information for municipalities in Santa Clara County.
  2. The design shall allow the user to direct the flow to the irrigation or disposal field or the building sewer. The direction control of the gray water shall be clearly labeled and readily accessible to the user.
  3. The installation, change, alteration, or repair of the system does not include a potable water connection or a pump and does not affect other building, plumbing, electrical, or mechanical components including structural features, egress, fire-life safety, sanitation, potable water supply piping, or accessibility. Note: The pump in a clothes washer shall not be considered part of the gray water system.
  4. The gray water shall be contained on the site where it is generated.
  5. Gray water shall be directed to and contained within an irrigation or disposal field.
  6. Ponding or runoff is prohibited and shall be considered a nuisance.
  7. Gray water may be released above the ground surface provided at least two (2) inches (51 mm) of mulch, rock, or soil, or a solid shield covers the release point. Other methods which provide equivalent separation are also acceptable.
  8. Gray water systems shall be designed to minimize contact with humans and domestic pets.
  9. Water used to wash diapers or similarly soiled or infectious garments shall not be used and shall be diverted to the building sewer.
  10. Gray water shall not contain hazardous chemicals derived from activities such as cleaning car parts, washing greasy or oily rags, or disposing of waste solutions from home photo labs or similar hobbyist or home occupational activities.
  11. Exemption from construction permit requirements of this code shall not be deemed to grant authorization for any gray water system to be installed in a manner that violates other provisions of this code or any other laws or ordinances of the enforcing agency.
  12. An operation and maintenance manual shall be provided to the owner. Directions shall indicate that the manual is to remain with the building throughout the life of the system and upon change of ownership or occupancy.
  13. Gray water discharge from a clothes washer system through a standpipe shall be properly trapped.

Questions or Broken Links? Call the Water Conservation Hotline at (408) 630-2554 or email us at [email protected].

Back to Graywater Rebate Page