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Graywater History: Timeline of Evolving Gray Water Standards in California and US
+Oasis Contributions

Last revised 2016

A history of evolving gray water standards. California-centric but includes the rest of the US.
Also includes history of Oasis Design contributions; essentially every technological innovation for simple home systems since 1989, all published unpatented into the public domain; as well as a strong role in improving regulations.


The impetus for this page is the recurring issues with keeping the current iteration of California greywater code distinct from the confusion of similar past versions. In the course of trying to unsnarl the current mess, I kept running into interesting history, which so far as I know isn't on the web anywhere. So, here it is.

Thanks to Larry Farwell, the guy who started it all in California; Jane Taylor of the California Building Standards Commission; and Steve Bilson, dogged legal warrior of ReWater Systems, for corrections, additions, and clarifications to this account.

Any remaining errors are my fault. If you have anything to add or correct, please  Email us .

I'd be interested to add early greywater history, like when it was made illegal in the first place.


—Art Ludwig, Santa Barbara, CA.

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1989—1st plant and soil biocompatible laundry detergent developed by Art Ludwig of Oasis Design at the University of California at Berkeley,  Personal note/ disclosure: My Dad sent me a newspaper clipping describing this historic legalization of greywater in our home town. It reached me right after I developed the first laundry detergent that biodegrades into plant food, at UC Berkeley, and while I was wondering what, if anything, to do about it. Oasis Biocompatible Products was launched in Santa Barbara on Earth Day 1990. We attained our one year sales goal ten days later. I sold this business to a competitor in 1996 and have no financial interest in cleaners now. We've never had a financial stake in any commercial greywater system. Sales of hard-to-find parts as a service for do-it-yourselfers (with depressingly low margins) comprise a few percent of our income. Sales of accurate greywater information currently (2016) supply about 40% of our income.

August 1989—Santa Barbara legalizes greywater. (The first district in the US with building codes to do so, it is said.) Santa Barbara Board of supervisors approves residential use of greywater in response to a letter from Goleta water district conservation office. This letter asks that greywater be redefined as separate from blackwater. Kitchen sink and diaper laundry water stay with toilet water under the "blackwater" heading. There is apparently no state prohibition of greywater; county is the only obstacle to overcome. Legalese: Appendix C: change to SB County Building Code ordinance 3665.

Spring 1991—1st edition of Create an Oasis with Greywater published. The first edition of the "Oasis Greywater Information" booklet was published in Spring of 1991, to save us from being stuck on the phone forever answering system design questions from our soap customers.

May 1991— Five other cities or counties have a greywater ordinance by this point. Santa Barbara County publishes "How to Use Greywater: Guidelines to the reuse of Greywater in Santa Barbara County."

Feb 5th, 1992— CA ad Hoc greywater committee releases Appendix W, which was based on the International Plumbing and Mechanical Official’s Uniform Plumbing Code (UPC) format, which California adopts as its model plumbing code. Appendix W provides only for mini leach fields, which can serve for greywater irrigation in a pinch, but are more suited for disposal of clarified septic effluent. Mini-leachfields as described in the code have not been built anywhere before this time, or since, so far as I know. More details 1.

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September 1992— Greywater legalized in any/all of 17 UPC based Western States. Appendix J was adopted by the UPC at a meeting in Anchorage, AK. People were stunned. No one was against it at the meeting; it just sailed through. But per IAPMO’s appendix, greywater was only legalized in any of the 17 UPC based Western States if they adopted Appendix J, and many local officials, who had not participated in the exchange of science during California’s state code process, and the fast tracked discussion for adopting Appendix J, refused to adopt it. It was eventually changed to Appendix G, some say to confuse people between California’s Appendix G and IAPMO’s Appendix G.

Note that this is a scant 3.5 years after Larry's first letter to the SB County board of supervisors. The advocates for this state law acknowledge that its immediate value has been nearly destroyed by anti-greywater zealots at certain cities and counties during the ensuing years, but it opened the door to the greywater regulation revolution that will pick up steam later in Arizona.

January 1995—ReWater Systems, Inc. sponsored Assembly Bill 313 (AB313, MacDonald, Bakersfield) to revise the state’s Appendix G to allow multi-family, commercial, and institutional greywater irrigation systems, as well as to allow protected connections to fresh water supplies for cleaning filters and supplemental irrigation. The same large group of stakeholders that were involved with AB3518 and more were involved in that 2-year code-writing process.  

On March 18, 1997, CA state code revised to allow multi-family, commercial, and institutional greywater irrigation systems, as well as to allow protected connections to fresh water supplies for cleaning filters and supplemental irrigation, and clean up some of the other difficult provisions. , still called Appendix G, was published and became available for use everywhere in California. Despite an effort by former IAPMO Director of Standards, Fady Mattar, then a Commissioner on the CBSC, to administratively delete the changes referencing fresh water connections, this California code remains unchanged.

The code version produced by DWR titled “Appendix G-A” is simply the version used by DWR. It is the same code as that used by the public.

2000—Green Septic system developed by Oasis Design.

January 16, 2001— Arizona addresses the dismal compliance rate issue by issuing one blanket permit for every greywater system in the state that meets a short list of reasonable requirements. Greywater regulation revolution! Opening the door wide that CA has cracked but only enough at that a few dozen permits are issued in ten years,

March 11th 2003— New Mexico adopts AZ style code. Greywater regulation revolution continues...Texas and several others adopt Arizona-style codes.

2007— CPC mistakenly incorporates an old version of the code into the body of the CPC as Chapter 16, thus administratively setting back permitting clarity a decade. The CBSC discovers this error and issues the correction as a canary colored “Errata” to be included in future code mailings or by request to the CBSC. The adoption matrix in the front of the CPC clearly shows that chapter 16 is not adopted and Appendix G is. Whew! What a mess. This is effective Jan1. 2008 ---probably until Jan 1. 2011.

April 27, 2007—Montana follows the civilized world in definition of greywater: Montana's greywater law HB 259 follows the European Union and Australian definition of greywater, which includes kitchen sink water.

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July 2, 2008— CA Senate Bill 1258 directs the Department of Housing and Community Development to develop a more wide-ranging set of standards for residential graywater systems for both indoor and outdoor uses. After another extensive debate on the science, these new standards will then be recommended to the California Building Standards Commission for adoption. This is a chance for California to catch up with the revolution it has started. Authority over non-residential greywater systems stays with CA DWR, which will probably stick with appendix G, as they have no funding for changes. Jan 1, 2011 (projected) In California the new HCD code (whatever it is) will take effect for residential, and DWR code (whatever it is) for commercial.

2008—Laundry to Landscape system developed by Oasis Design. It quickly becomes the most popular greywater system in California, with a few dozen jurisdictions offering rebates and numerous installers.

Early 2009— Nevada submits bill for AZ style code (in process). Greywater regulation revolution continues...

Aug 4th 2009—CA adopts chapter 16a, Non-potable Water Reuse Systems. This is the culmination of years of stakeholder code development process, and probably the version of the CA code to copy (if for some reason you don't want to use our Model greywater rules (pdf). It pioneers the permit-free laundry systems in California, which meet standards largely authored by Oasis Design.

June 11th, 2013 — for some reason we let ourselves be talked into IAPMO scrambling the carefully wrought greywater code into their Chapter 16 in the 2013 CPC. If I remember correctly, the point was to combine it with rainwater, then rainwater ended up somewhere else, and we almost got the old greywater code back, but IAPMO went ahead and left it scrambled, creating pointless work and confusion for everyone who had spent decades working with the old layout. In substance it is allegedly the same. Rumor has it that this may have been pique about California turning it's back on their UPC and making their own greywater standard that was widely perceived as superior to the IAPMO version. Now if you want a copy of the code you are invited to buy it from IAPMO, or make use with their locked, un printable, un-copy and pastable Chapter 16 PDF version...thankfully, the entire 2013 CPC, along with every other California Building Code is available online for free from Public Resource. (They apparently argued successfully that the Law As Passed By Our Elected Representatives should be available without paying a high fee to a business-duh: The courts have long held that the law is public domain and must be available to all for use without restriction. While numerous organizations have attempted to assert copyright over judicial branch opinions, legislative branch statutes, and executive branch regulations, the courts have not looked kindly on these efforts to place a private wrapper around a public package. If we are to be a nation of laws, those laws must be accessible to all.

So few jurisdictions have registered this inexplicable switch or updated their public information materials that it might make sense to go back to the August 2009 version in the next California code revision and save California regulators the trouble of revising everything they'd developed from 1990 to 2009.

Late 2015—Santa Barbara County allows permit exempt "simple" greywater systems. I believe this is a first in California...details.

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1 More mind-numbing detail.....

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See also:

  • Greywater how-to books & video Set —All our greywater books and video together at a discount
  • Oasis greywater-book  —How to choose, build and use 17 types of greywater systems
  • Laundry 2 landscape-video —How to build our simplest, most economical system from start to finish
  • Builder's GW Guide-book —Permitted greywater systems in new construction and remodeling, info for regulators and policymaker