Alert 2/5/21 | 2:42 PM: Valley Water continues to monitor the ongoing COVID-19 pandemic, your water remains safe. LEARN MORE HERE
Water Conservation
Help make conservation a California way of life
saving water header
Page Title
Saving Water
Back to top

Graywater Resources


This graywater resources webpage provides a graywater introduction, how-to videos, resources on finding equipment and installers, maintenance tips, soap and plant health, and more. Graywater is produced from bathroom sinks, showers, bathtubs, and washing machines. This page provides what you need to know to use graywater safely in your own home and landscape.

Don't have time to read all the content on this page?

No need to wait: you can attend our virtual graywater workshop! Divided into 4 parts to make it easy to learn more at your convenience. Here are slides from a Spring 2019 graywater workshop.

Click this System Example and Parts List to view and download a larger image.

Benefits of Graywater Use

Graywater is beneficial both for residential users, as well as for the environment. Graywater is a purely local water supply -– it is both produced onsite and used onsite as close to the point of production as possible. If graywater harvesting is appropriate for a site, it can provide a substantial quantity of local water for reuse.

“It's a waste to irrigate with great quantities of drinking water when plants thrive on used water containing small bits of compost. Unlike a lot of ecological stopgap measures, grey water reuse is a part of the fundamental solution to many ecological problems…” -- Art Ludwig

Potential Benefits

Water Conservation

  • Reduce potable water use by 20-65%, depending on the house/site
  • Reduce water bills due to decrease in potable water use and sewer effluent output
  • Gain LEED and Green Building Rating System points

Waste Water Reduction

  • Alleviate stress on septic systems or treatment plants
  • Reduce energy and chemicals used to treat the water to potable standards at the wastewater treatment plant
  • Reduce household effluent sent to treatment plant – thereby reducing energy costs to treat and/or reuse water
  • Improve quality of household effluent to waste treatment plant


  • Encourage the use of nontoxic products
  • Improve soil condition and plant growth with nutrients in the graywater, which can nearly match those of commercial fertilizers
  • Recover nutrients such as nitrogen and phosphorus
  • Reduce dependency on imported water or local aquifers
  • Increase groundwater recharge
  • Connect people to their household water supply as well as to their watershed
  • Encourage understanding of the water cycle and local watersheds

Climate Change Action

  • Provide drought insurance for landscapes
  • Provide a fire break and/or greenbelt of high-moisture species
  • Encourage knowledge of localized water use, treatment and reuse
  • Irrigate shade trees near your home to reduce energy costs

More information and sources can be found at

Frequently Asked Questions

Graywater Frequently Asked Questions


  • What is graywater? Graywater is untreated, gently used water from bathroom sinks, showers, bathtubs, and washing machines. It is not water that has come into contact with diapers or similarly soiled or infectious garments, and it is not water that contains hazardous chemicals from activities like cleaning car parts, washing greasy or oily rags, or similar sources. Graywater does not include waste water from kitchen sinks, dishwashers, or toilets. 
  • Getting Started with Graywater [PDF] provides a simple overview of steps to plan a laundry-to-landscape graywater system, estimates project costs, potential water savings, and a summary of additional resources available on this website.
  • 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, adding an reverse-osmosis system, or trying alternatives to conventional ion-exchange water softeners [PDF and study evaluating water-softener alternatives]. Or, consider softening just hot water, which will reduce the amount of salt in your graywater or eliminate it if you commit to using cold water when washing clothes.
    • What’s the difference between sodium chloride and potassium chloride water softeners?
      Salt, or sodium chloride, is commonly used in water softeners to remove the hardness from water in homes and businesses. Potassium chloride works exactly the same way that sodium does in the water-softening process. However, there has been a slow but steady growth in the use of potassium chloride (KCl), which is chemically related to salt and has the same water-softening characteristics. Most water softeners remove hardness (calcium and magnesium) and iron from water through an ion-exchange process. The harder the water, the more sodium or potassium respectively is added to effect softening.
    • How does potassium chloride benefit the environment?
      Potassium chloride is a naturally occurring mineral, and it is often marketed as an agricultural plant food. Sodium can be harmful to plants, whereas potassium is an essential mineral for plant growth. By switching from sodium chloride to potassium chloride, it will reduce sodium and chloride being discharged into municipal wastewater treatment facilities, thus enhancing the quality of recycled water and soil conditions.
    • How do you change regenerants?
      If you switch from using salt to potassium chloride, you may just add the potassium chloride pellets into the tank where salts are added. No equipment changes or adjustments are required for most household water softeners; however, please refer to your owner’s manual or contact manufactures for compatibility. Also, please consult your physician if you have any health-related questions about consuming potassium chloride-treated soft water.
  • What about my reverse-osmosis (RO) system? Free of minerals and salts, an RO system's water is graywater-friendly (just send the RO concentrate to the sewer).
  • What about my septic system? Every septic system is different, but you may need less frequent leachfield replacement by sending more of your laundry rinse water to the landscape with a graywater system.
  • What about microplastics? Whether in the oceans and rivers or the soil, it's important to minimize plastics in our natural environment. Detergent, washing behavior, and clothing choices are most effective to minimize this fact of our modern world. To reduce the risk of releasing microfibers while doing laundry, minimize friction on your clothing by using liquid detergents, and washing your clothes on cold-water settings with full loads. Natural fibers such as cotton, linen, and wool will eventually break down in the environment (unlike plastics). Choosing to use liquid detergents, cold-water settings, full loads of laundry, and only natural fibers are effective ways to minimize plastics in the environment (whether in the ocean or your graywater-irrigated landscape). To further reduce the amount of plastics in the environment, new products on the market to consider include wash bags and washing machine lint filters.
  • Where can I find information on recycled water and rainwater systems? 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 the simplest graywater system? The simplest graywater system is a bucket to collect warm-up water in your shower. Buckets with graywater can be used to flush toilets or used in your landscape. Siphoning graywater while adhering to local codes is another simple way to use graywater. Keep reading to learn of more permanent and cost-effective graywater systems.

  • 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):

Soap and Detergent Information

Graywater Soap and Detergent Information

  • List of plant-friendly soaps and detergents
  • Soaps and detergents from Greywater Action based on their experience and expertise working with graywater-irrigated landscapes. When product labels aren't sufficient, general Information can help find graywater-compatible or garden-friendly detergents when product labels aren't sufficient with additional graywater resources not included on this webpage.
  • Choose:
    EPA Safer Choice Products
    USDA Biobased Product Lists
    • Liquid detergents free of Boron, bleach, antibacterial compounds, and fabric softeners which can degrade the health of your landscape's soil over time.
    • Biobased products without petroleum compounds (USDA Certified Biobased Product label)  
    • 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 - Use the graywater system's diverter valve to send to the sewer any detergents with the chemicals below:
Salts and Boron Chlorine Bleach
Petroleum distillate Antibacterial compounds
Whiteners Fabric Softeners
Enzymes and Paraben compounsd 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.)


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.

Equipment Information

Graywater Equipment Information

  • Essential components include:
    Essential Components
    • 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), PE (polyethylene), 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 Directories for the
  • Green Gardeners may have sufficient knowledge to install 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 menuselect 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 may be helpful after using the resources above.

Mulch Basins and Soil Health

Graywater Mulch Basins and Soil Health

Mulch Basin Side View
  • A mulch basin is a trench dug around the outer edge of plant's drip line and back-filled with mulch. A plant's "drip line" is an imaginary line drawn from the outside branches of a plant down to the soil (see inset image). The graywater pipe is protected in a "mulch shield", separated from the surface above and more mulch below. This setup allows graywater to spread widely and deeply into your soil, while preventing runoff or ponding of graywater. Maintenance typically includes checking the ends of the graywater pipe for obstructions to remove and replacing the mulch as it composts over time. Coarser mulch will last much longer than finer mulch.
  • Learn about different types of mulch to place in your graywater system's mulch basins (Review the How-To Videos other examples). 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.

Maintaining Your Graywater System

Graywater Maintenance

Maintaining a laundry-to-landscape system is considerably easier than other types of graywater system since there are no filters or tanks to clean-out. Most maintenance tasks should be done at least annually or if you notice water in unusual places. It is best to direct graywater to the sewer/septic system during the rainy season to ensure graywater never pools or ponds on the soil surface.

This section describes steps you can take to ensure your graywater system will continue running smoothly for years to come. This video from Greywater Action provides an effective, quick summary of how key maintenance steps look in action.



Inspection Schedule


3-Way Valve


Check for leaks at washer hose, and make sure label is in place.

There should never be moisture at the 3-way valve. If leaking, tighten the hose clamp.

Relabel if needed. Labels should clearly show which direction the graywater is flowing for how the valve's handle is oriented.

Auto Vent


Check for leaks from the auto vent. If leaking, replace the auto vent.
There should never be moisture at the auto vent. If leaking, replace the auto vent.

Piping and Tubing

Annual, or if you notice water in unusual places

Check for leaks. If piping or tubing is leaking,  cut out the damaged section and reconnect with couplers or barbed couplers. The coupler size will depend on your pipe size (either 1/2-inch, 3/4-inch, or most likely 1-inch).

Relabel if needed. Exposed piping should be labeled, "Caution: Nonpotable graywater. Do not drink.".

Discharge Outlets

Annual, or if you notice water in unusual places

Check for even distribution.

Unclog particles that have built up in the outlets.

Open all ball valves, and if needed flush the system by running rinse cycles. Another option is to temporarily separate the PVC union to access the piping by temporarily disconnecting it from the clothes washer. 

Mulch Basins


Remove decomposed mulch and add new mulch.

If water is pooling or ponding, dig out the mulch basin so it has a larger surface area and add new mulch.

If the plant has grown past the outlet, dig up the mulch and soil surrounding the outlet and piping up to the plant's current drip line. Cut the piping and place the mulch shield/valve box at the new location under the drip line. Ensure the pipe outlet is 2-inches below the soil surface. If you cut the pipe too far, use a barbed coupler and some hot water to join the two pipe pieces back together (either 1/2-inch, 3/4-inch, or 1-inch depending on the pipe size).

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

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] will open to an overview of clothes washer (Laundry to Landscape) graywater systems that don't require a construction permit (Section 1502.1.1 on pages 353 and 354 of the linked PDF, or pages 310 and 311 of the printed version.). Summarized below. Check with your local building or permitting department for additional rules to consider when planning your project. 

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. Building Department Contact Information (subject to change) 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