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Graywater Resources


Graywater laundry to landscape rebate

This graywater resources webpage provides a graywater introduction, how-to videos, resources on finding equipment and installers, soap and plant health, and more. Use the Table of Contents immediately below to quickly navigate the resources on this page:


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? Click here for information on recycled water, and click here for rainwater systems like rain barrels and more. Graywater has different requirements and benefits than recycled water or rainwater systems.

Plants and Soaps

  • 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, whereas 

    • a top-loading clothes washer can provide water for 2-3 trees for every load per week.

    • 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)

  • Can I use graywater to grow vegetables? 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. Graywater can be used safely with fruit trees or berry bushes. Additional important information can be found below.

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.

  • 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):



How-To 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, graywater system overviews, and more.

Instructional Videos

Overview Videos

 

Equipment Information

The section below provides information on what equipment is typically needed for a Graywater Laundry to Landscape System, including where you may be able to find some of the harder-to-find components.

  • 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 at the top of the System 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.



Finding Installers 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.

  • Additional lists of landscape professionals can be found here.



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.

    In the “Search Products” area, 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 compound

    • Whiteners, softeners, enzymes, paraben compound

    • 1,4-dioxane (This may be found in certain detergents identifiable by the prefix, word, or syllables "PEG," "Polyethylene," "Polyethylene glycol," "Polyoxyethylene," "-eth-," or "-oxynol-.")

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

  •  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.

 

Other Technical and Design-Assistance Resources

 

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 System Requirements for the rebate program. 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.
  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 Conservation@valleywater.org.


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