Greywater has been a touchy subject in San Diego for decades, but people are being encouraged more and more to come out of the “water closet” with their greywater use.  In fact in some parts of San Diego, homeowners are being required to use greywater.    We have had some serious deregulation of greywater use here in San Diego starting back in 2009 with emergency rules allowing greywater use due to severe drought to today where two cities in San Diego County have specific regulations requiring greywater stubouts in new single-family homes.   CatchingH2O has been keeping up with these regulations, pulling permits in almost every city in the county, and demystifying greywater for thousands of homeowners and business owners.

“No permit” clothes washer system

There is a big difference between the “no permit” clothes washer system and a whole house greywater system.  In this blog we will discuss options for new construction and major remodels.  Please feel free to contact us for a consultation or join one of our upcoming classes to learn more about simple retrofits.  In order to understand what the regulations are in your part of town, what system is most appropriate for you, and how to best utilize your water here are some helpful resources and tips.

Water budget: how much water are you producing?  

In 2015, the shower flow rate in California was mandated at 2 gallons per minute by the California Energy Commission. If you take a 10 minute shower that’s 20 gallons a day.  If 4 people take a 10 minute shower every day, that’s 80 gallons.  Note: you can get high quality 1.5GPM showerheads, and save thousands of gallons a year

Lavatory sinks manufactured after 2015 have a 1.2 GPM flowrate and can provide another 5-6 gallons per day depending the number of household residents.  It’s possible to get 0.5 gallon aerators for your bathroom sinks to save even more water.

Check the table below to figure out your weekly laundry water budget.  If you do 4 loads of laundry in a newer front-load washing machine, that’s only about 40 gallons for the whole week. A family of 4 may do from 4 – 14 loads of wash per week depending on the ages and activities of the family members.

Top/Front How Old Water Budget
Top 10+ 50
Top 1-10 25
Front 5+ 25
Front 1-5 10

Kitchen sinks and dishwashers are not included in your greywater budget.  This water typically has higher bacteria, solid waste, grease, and salt content and it is not permissible to release this water in your yard.

So in the example above with a 4 person household, the greywater supply per week may be from 500 – 750 gallons per week based on a range of shower times and laundry loads.

Landscape Matching

Next you want to consider the following

1. Soil type – affects percolation. Learn how to do your own percolation test here.

2. Area – determines if you have the space to percolate all your greywater

3.  Slope – determines pump size or gravity potential for greywater

4. What kind of plantings do you prefer – fruit and other trees, shrubs, and many native plants are excellent choices for your greywater. Greywater cannot be used on most vegetables. Although greywater can be used to irrigate turf , it is not recommended as grass needs overhead spray to become established and greywater must be released a minimum of 2″ under mulch or soil.

Codes and Permitting

As you beginning your planning process, take into account the plumbing orientation relative to the landscape.  There are two different options:

1.  Route all your greywater to a central location to be pumped to your landscape

2.  Route each shower and your laundry machine out to different/nearby areas to be watered.

If there is a chance you can craft your landscape appropriately, #2 might be a great option for you to reduce cost and use gravity fed greywater from individual fixtures.  If your landscape will require a central, zoned irrigation theme you may find #1. a better option to more evenly distribute your greywater throughout your landscape. However, if you live in the city of San Diego, there are some additional requirements over and beyond the California plumbing code that make #2 virtually impossible because surge tanks with overflows to the sewer or septic are required for all permitted greywater systems.


Two cities in San Diego currently have some greywater requirements for new development:

Chula Vista

15.28.020 Residential graywater stub-out.

All new detached single-family dwellings and duplexes shall include a single-source clothes washer graywater outlet and an outside stub-out to allow the later installation of a clothes washer graywater irrigation system that complies with the requirements of Section 1502.1.1 of the 2016 California Plumbing Code. The outlet and stub-out shall be installed in accordance with the Chula Vista clothes washer graywater pre-plumbing and stub-out for new residential construction or an equivalent alternate method and/or material approved by the Building Official.

The provisions of this section may be modified or waived when it can be satisfactorily demonstrated to the Building Official that compliance with these regulations is impractical due to construction or physical constraints, or due to site and/or soil conditions. (Ord. 3391 § 1, 2016; Ord. 3290 § 1, 2013; Ord. 3263 § 2, 2013).

Laundry greywater manifold (Left) and basins awaiting greywater (Right)


Effective September 20, 2015, all new single-family homes must be pre-plumbed with gray water plumbing to all gray water eligible discharge sources and with a stub-out convenient for connection to the landscape irrigation system.  Refer to Ordinance 2015-11.

This is great information for you to know, but just because you know it, and just because it’s written in there, doesn’t mean it is being enforced correctly or even that it is the appropriate requirement for our new development.   We know that Encinitas was not even enforcing this code until recently and even now there is much debate on how greywater stubouts should be implemented because there isn’t a general knowledge in the building industry about these things.


Greywater diverter valve (Left ), valve key (Middle) and valve in landscape (Right).

This code in Los Angeles implies a completely different requirement for “Greywater Ready” plumbing in new construction

5.305.1. Graywater Ready. Waste piping shall be arranged to permit the discharge from the clothes washer, bathtub, showers, and bathroom/restroom wash basins to be used for a future graywater irrigation system. The flow from the fixtures shall be piped separately, and shall, at a minimum, be adequate to supply the irrigation demand. The point of connection between the graywater piping and other waste piping shall be accessible (as defined in LAMC Section 99.02.202) and provided with signage that is satisfactory to the Department. 

The difference in this language is that all the fixtures need to be separated.

How do you need to talk to your Architect, General Contractor, Plumber about greywater in order to make sure they are on the same page:

1.  Plumbing fixtures near an outside wall (if separating fixtures for greywater use) make it easier to use gravity fed (lower cost) systems.

2. If greywater needs to be distrubted more broadly or you are routing all your greywater through a central system, greywater pipes should be routed out to an area that can contain a 30″  diameter surge tank.

Greywater surge tanks (Left) under decorative walkway and (Right) in front garden bed with diverter valve adjacent under 6″ pipe.

3.  Greywater pipes should maintain 1/4″ per foot fall but stay as close to the surface as possible so that the surge tank doesn’t need to be excessively deep to maintain volume below the inlet pipe elevation.

During a remodel is a great time to adjust your existing drain pipe.  By connecting with the contractor in this project early on, we were able to get this new line several inches higher than the plumber originally intended.   From here, the water can drain to a lower point in the landscape.

4. The 3 way valve needs to be placed in an accessible location with either an access panel if indoors or a convenient location for an access riser if outside. A sewer tap will also be needed for the required connections to the sewer from both the 3 way valve and surge tank overflow.

You might wonder why these regulations and requirements should be in place, and why greywater should be part of your decision.  Consider this local example:

A little number crunching helps us see what kind of impact many households make.  For example, the San Luis Rey Water Treatment Facility serves Oceanside, Vista, and Rainbow.  If every household in this area redirected their laundry greywater to their landscape, 1.31 million gallons of water per day would be turned from an expensive waste product to a high quality resource!  Not only that, but instead of investing millions of dollars to increase the facility’s ability to process more water, we could advocate for much less money to be distributed directly to households to implement these systems and have thriving landscapes!   We would be solving several issues related to water management (supply, watershed management, waste water) rather than the single solution that creating more infrastructure to manage waste water.

Another example looks at new construction and planned communities which is likely to be a part of our future.  Suppose one of the new planned communities in San Diego county put in whole house greywater systems for all of the homes? In San Marcos, the Rancho Tesoro development will have about 400 homes on 250,000 acres. If each of these homes used their greywater for irrigation, not only would there be over 3 million gallons of water saved annually but potentially these homes could design their landscapes so that city water is not needed there for outdoor irrigation. Ideally these homes would also divert their rainwater runoff from roofs and hardscapes into their landscapes as well, so that our beaches and rivers are protected from contaminants in stormwater runoff.

CatchingH2O is poised to help you navigate new construction as well as retrofits to maximize the benefits of your onsite greywater and rainwater!  Now is the perfect time to get started.  Sign up for a consultation now!

Demystifying Greywater for New Construction

Leave a Reply

Your email address will not be published. Required fields are marked *