Greywater Considerations
& Options
What is
Benefits, Facts
& Guidelines
Is Greywater
Legal in CA?
Laundry to Landscape
What is Greywater?
Greywater (also spelled graywater, grey water, gray water) is water that has been used in households or other buildings. It is not water from toilets or from washing soiled diapers -this is often called blackwater. Both types of water are often called "wastewater". We dislike this term because of the word "waste". Waste is nothing but an unused resource.

Sources of greywater include bathroom sinks, showers, tubs, and washing machines -kitchen sinks can be too but not yet in California. As greywater contains fewer pathogens than blackwater it's generally safer to handle and easier to treat and reuse onsite for landscape or garden irrigation, toilet flushing, and other non-potable (non-drinking) uses.

Why use greywater? Greywater reuse is one important solution to the many ecological problems we face today. Using grey water can help reduce stress on water supplies, lower home water usage and costs, and support a thriving landscape. Why irrigate your landscape with large quantities of drinking water when many can plants thrive on reused water?
  1. bathroom faucet
  2. shower head
  3. washing machine
  4. bath faucet

Through the natural water cycle, the Earth has recycled and reused water for millions of years.  Reusing greywater reconnects us and our landscapes to this natural water cycle.
Greywater Benefits, Facts & Guidelines
  • Lower fresh water use (we don't need to use fresh drinking water to irrigate our landscapes!)
  • Less strain on septic tanks (bypassing the septic tank increases its overall lifetime)
  • Better treatment of water (topsoil is many times more effective than subsoil or treatment plant)
  • Less energy and chemical use (treatment plants use vast amounts of energy and chemicals to "purify" water)
  • Groundwater recharge (in our area this is vital!)
  • Reclamation of otherwise wasted nutrients (nutrients from greywater are used by our plants)
  • Increased awareness of our landscapes (encourages us to use environmentally friendly products)
  • Saves time (when used in the landscape it's an automatic irrigation system) 

Californian's produce ~1 billion gallons of greywater everyday!
Dish, shower, sink, and laundry water comprise 50-80% of residential greywater. Reusing greywater from laundry and bathroom(s) can save about 15,000 to 36,000 gallons of freshwater each year -a typical family of four produces about ~100 gallons/day of greywater = 36,000 Gallons/year.

If just 10% of homes in densely populated Southern CA used their washing machine to irrigate their yards, that would produce around 40 million gallons of greywater a day. If that water went into the ground rather than to wastewater treatment facilities imagine the water and energy savings!

Most homes can reduce their water consumption by 16-40% by reusing their greywater. How much you'll save depends on how many sources of greywater you can access and how much you currently irrigate.

Greywater is easily used in the landscape for perennial plants
Basic Greywater Guidelines
  • Greywater is different from fresh water and requires different guidelines for it to be reused.
  • Don’t store greywater (more than 24 hours). If you store greywater the nutrients in it will start to break down, creating bad odors.
  • Minimize contact with greywater. Greywater could potentially contain pathogens so your system should be designed for the water to soak into the ground and not be available for people or animals to drink.
  • You can use greywater on edible plants, but only fruit trees or crops such as corn or raspberries, where the edible part is off the ground. Do not use greywater to irrigate root vegetables or other crops it comes into contact with.
  • Infiltrate greywater into the ground, don’t allow it to pool up or run off -knowing how well water drains into your soil -or the soil percolation rate will help with proper design. Pooling greywater can provide  mosquito breeding grounds, as well as a place for human contact with greywater.
  • Keep your system as simple as possible, avoid pumps, avoid filters that need upkeep. Simple systems last longer, require less maintenance, require less energy and cost less money.
  • Install a 3-way valve for easy switching between the greywater system and the sewer/septic.
  • Match the amount of greywater your plants will receive with their irrigation needs.
For more Greywater FAQ go to Greywater Actions' website.
Is Greywater Legal in Calfornia?

Graywater use is legal in California. In 2009, California’s graywater regulations changed, allowing for lower-cost graywater systems to be installed legally, including some without the need for a permit. Some cities have made the permitting process relatively easy and straightforward, but unfortunately not all places have, so obtaining a permit can still be a barrier for legal greywater systems in CA. We need to keep working to improve our code so people can install all types of legal greywater systems and have it be affordable and easy to do.
As of 2017, California’s greywater code is found in Chapter 15 of the California Plumbing Code (CPC) (previously it was in Chapter 16).

Before 2009 it was not possible or cost prohibitive to install a legal system, so there were 1.6 million illegal systems in California. Since 2009 it is possible to install several types of systems legally and some don't require a permit.
When a Permit Is Not Required
You can install a greywater system for outdoor irrigation without a permit if you meet all of the following requirements:
  • Greywater comes from the washing machine only
  • Greywater system does not alter the household plumbing (you access graywater from the hose of the machine, not by cutting into the plumbing)
  • Greywater system is for a one- or two-unit residential building
  • Greywater system follows 13 guidelines set forth in the California Plumbing Code

When a Permit Is Required
You need a permit to install a greywater system for outdoor irrigation when your greywater system:
  • Collects water from showers, sinks, or baths
  • Alters the plumbing (you cut into drainage plumbing to access the graywater)
  • Is installed in a building that is not a one or two-unit residential building
  • Includes a pump (besides the washing machine’s internal pump) or a tank

Greywater in Butte County
Each county and/or municipality has the option to further refine/restrict California law regarding greywater
  • Laundry to landscape (L2L) systems are legal in Butte County without a permit
  • No further restrictions in other cities in Butte County other than Paradise (that we know of)
  • The permit application fee in Paradise is $97.25 for all types of systems
  • Permitting is available for other types of greywater systems
  • Follow California laws (chapter 15 of the CPC) and you’re good to go…
For more Greywater Code go to Greywater Actions' website.
Greywater Considerations & Options

Things to Consider
1. Goals for greywater (reuse or disposal?)
2. Site considerations:

  • Access to drain pipes
  • Slope of the land
  • Drainage and infiltration of soil
  • Proximity to creeks and waterways
3. Quantity of greywater produced (anticipate future changes)
4. Irrigation needs of plants (suitability for greywater; easiest plants to irrigate are fruit trees, fruiting shrubs, large annuals and perennials)
5. Desired maintenance level (experimenters vs. bare minimum effort)
6. Permit needs and budget

What you put down the drain affects the plants you irrigate with greywater!

Read Labels and Avoid:
  • Salts and sodium compunds (damages soil)
  • Borax, boron (micornutrient turns into toxin)
  • Chlorine (kills bacteria/life)
Option #1 Washing Machines

Key Points
  • Front loader 10-20 gallons/load
  • Top loader 30-50 gallons/load
  • Easy to access without cutting into house plumbing
  • Washing machine pump sends greywater to plants
  • Easy for household to switch to greywater friendly products
  • No permits needed in California if 13 guidelines are followed

Types of systems
Laundry to landscape: The washing machine pumps greywater directly to plants.
Option #2 Showers/Baths & Sinks

Key points
  • Showerheads: 1-2.5 gpm; sinks 2.2 gpm.
  • Requires cutting into drainage plumbing
  • Requires a permit
  • Kitchen sinks not considered greywater in California

Types of systems
Branched Drain: Greywater flows outside by gravity through pipes to mulch basins around trees and shrubs.
Pumped system: Greywater drains to surge tank, then is pumped out to plants.
Constructed wetland: Greywater passes through wetland, which removes nutrients and transpires water.

Option #3 More Complex Systems

  • Sand filter to drip irrigation: Pressurized system that removes particles in greywater with a sand filter, which is automatically cleaned by being backflushed with domestic water.
  • Indoor reuse for toilet flushing: Not allowed under present code, indoor code currently being written. Typically not appropriate for residential, best for commercial and industrial scale systems.
  • Manufactured systems: All systems relatively new, include tank/pump/filter, subsurface drip -which require maintenance and can break.
  • Typical cost is $7,000-$15,000
Read City of San Francisco's Greywater Design Manual
Laundry to Landscape Systems

Since 2009, the California code does not require a permit or inspection for clothes washing systems that do not alter the existing plumbing as long as the installer follows the guidelines below:
Summary of requirements

The system must:
  • Have an easy way to direct flow back to the sewer/septic (like a 3-way valve). The valve must  be labeled.
  • Send the water to irrigate landscape plantings
  • Keep the water on the same property it is produced and follow set-backs listed in the code
  • Have a maintenance manual
  • Discharge greywater under a 2″ cover of mulch, plastic shield, or stones

The system must not:
  • Contain diaper water
  • Contain hazardous chemicals (such as from a home photo lab)
  • Have pooling greywater or runoff
  • Make greywater accessible to people or pets (such as in an open tub)
  • Include a pump (except the washing machine’s internal pump)
  • Connect to the potable water supply
  • Affect other parts of the building, such as the electrical or structural components
  1. mulch shield lid -purple lid
The laundry-to-landscape system is legal to install
without a permit as long as these guidelines are followed.
Text from the Chapter 15 of the California Plumbing Code:

Clothes Washer System
A clothes washer system in compliance with all of the following is exempt from the construction permit specified in Section and may be installed or altered without a construction permit:

  1.   If required, notification has been provided to the Enforcing Agency 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 graywater 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 graywater system.
  4. The graywater shall be contained on the site where it is generated.
  5. Graywater 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. Graywater 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. Graywater 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. Graywater 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 graywater 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. Directions shall indicate the manual is to remain with the building throughout the life of the system and indicate that upon change of ownership or occupancy, the new owner or tenant shall be notified the structure contains a graywater system.
  13. Gray water discharge from a clothes washer system through a standpipe shall be properly trapped in accordance with Section 1005.0
Greywater Services
Laundry to Landscape Systems
Design: $100-$300
Materials: $150-$300
Full Design & Installation Cost: $500-$2,000
Branched Drain Systems
Design: $100-$600
Materials: $200-$700
Full Design & Installation Cost: $700-$5,000+
Check out our Other Services
We are greywater installers certified by Greywater Action. Greywater Action is a collaborative of educators who have taught thousands of tradespeople and worked with policymakers and water districts to develop codes and incentives for greywater.
  1. l2l system indoors
  2. purple mulch shield
  3. mulch shield cover -purple lid
  4. mulch shield