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California Graywater Policy Center: Suggestions and Resources

Introduction—The Need for Greywater Standards that Californians Will Follow

Dear Gray water Stakeholders:

The gray water regulation revolution was started in the US in 1989 in Santa Barbara, California. It spread from there to four other communities, then the whole state of California, via the Uniform Plumbing Code, in 1992.

Since then California's greywater regulation innovation has been at a standstill, and the rest of the West has left us in the dust (apart from a bit of improvement in 2009...see History of greywater regs).

It is certainly true that "plumbers safeguard the health of the nation," and it is doubtless that building and plumbing codes have saved many, many lives. However, California's gray water regulations are not making a good example of the positive role plumbing codes usually play in civil society.

There are about two million greywater systems in the state of California. One in ten thousand has a permit. There's been no reported cases of greywater-induced illnesses. (References follow below). There is a principle that regulation should be realistic and proportionate to risk...alas, greywater regulation in California is wildly unrealistic and disproportionate to risk.

California did not permit greywater systems at all pre-1992, then had rules so unrealistic only a few hundred of the states two million systems were permitted between 1992 and 2009.

Concern about public health is the oft-cited reason for keeping regulations tight. It seems that concern about optics and apparent liability are the actual issue. (This would explain why no one blinks about unpermitted systems (not a liability or optics issue), while few regulators dare permit anything.

This is completely counterproductive for lowering actual risk. The only people dissuaded by the tight control of permitting are building professionals—plumbers, builders, landscapers, that is, those who might otherwise develop experience and expertise. It is hard for a homeowner to get help from a licensed professional to make an illegal system. So, they go out the back, and do it themselves.

The current greywater regulation approach hinders best sustainability practices, and undermines respect for codes in general.

Realistic greywater codes of the type adopted in Arizona (2001), New Mexico (2003), Texas (2005) and in process in several other states (NV, OR, MT...) are emblematic of the shift that occurs when the blinders come off and the full risk profile is taken into account in crafting policy.

If California regains its leadership position, the rest of the world is essentially certain to follow.

I look forward to working with you to get the new greywater standards headed towards this goalpost, as envisioned by the sponsors of the enabling legislation.

We've decided to put some resources behind this effort. Here's what we've come up with so far. We'll be adding more, including responses to HCD's and the Greywater Working Group's material.

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Current Greywater Regulation in California

History of greywater regs is interesting and bears on the present and future in many ways...check it out. OurCalifornia Graywater Code page has the current law of the land. At last, this includes permit exemption for laundry-only greywater systems that meet these

Laundry-only California greywater system standards:

1603A.1.1 Clothes Washer System and/or Single Fixture System.

A clothes washer system and/or a single fixture 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. Note: A city, county, or city and county or other local government may, after a public hearing and enactment of an ordinance or resolution, further restrict or prohibit the use of graywater systems. For additional information, see Health and Safety Code Section 18941.7.

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.

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.

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Unified Policy for Permit Exempt Graywater Systems Under the California Plumbing Code

We are currently at work on a Unified Policy for Permit-Exempt Simple Graywater Systems as local jurisdictions are allowed to do Under the California Plumbing Code. Here's the rationale developed early in the program, and here are the adopted guidelines. Please check back for later revisions. To send comments, please Email us (If you need to send attachments email us and we'll email back with our attachment-capable address).

For an analysis of greywater safety and context that explains the counterintuitve fact that exempting greywater from onerous permitting improves environmental health, see this webinar on Water Reuse: Making the Most of What We Have While Protecting Public Health for the Public Health Alliance of Southern California.

I ranked the relevant sections in order of importance for this topic; if you are in a rush you could just review the big bold bit, about 6 min, if you have time you could spend 20 min on the video that isn't greyed out:

0:00 intro
7:03 Art presentation

7:50 Optimal integrated design/ systems thinking
15:15 greywater background
17:30 greywater safety analysis
23:56 greywater purification mechanism
26:45 how best to regulate greywater
31:54 local exemption
49:27 end of GW

Slide deck for this presentation

ACTION: Want to help this be implemented? Ask your water purveyor to send the Chief Building Official(s) in their service area a letter of support for this policy. Please Email us a copy, too. (If you need to send attachments email us and we'll email back with our attachment-capable address). Sample letter:

Dear [name of Chief Building Official(s)]:

The [name of Water Purveyor] supports a policy to exempt simple greywater systems from permit, as provided for in the Section 1602.1.2 (2) of the California Plumbing Code.

Greywater systems offer the following benefits for our community:

• Help balancing our water budget through reuse for irrigation
• Reduction of loading on septic systems, improving treatment and extending system life
• Reduction in nitrate in our potable groundwater, by reducing the speed and volume of wastewater plumes from septic leach fields, and most especially from drywells
• Reduction in introduction of toxic chemicals to groundwater by disincentivizing their use
• Reduction in fire hazard by hydrating vegetation near homes
• Greater resiliency in case of water shortage
• Lowered ecological impacts from reduced water withdrawals

Thank you for your efforts to streamline compliance for alternate water supply at this critical time.


[name of Water Purveyor]

Actual letter from the Goleta Water District to the Santa Barbara County Building Official. I believe Goleta Water customers in the unincorporated area are the first Californians to enjoy legal, permit exempt simple greywater systems. San Francisco PUC is actively working on this, and several other districts are on the brink.

Improvements Needed

(note: for the most current information, refer to our Builder's GW Guide-book.)


Our letter to HCD Feb 24th, 2009

Re SB 1258: Please discard the UPC model and use the state-of-the-art Arizona/ New Mexico/ Texas tiered approach to greywater regulation [Note: this partially succeeded, with the permit-exempt laundry standards and allowance for local jurisdictions to allow permit-exempt simple systems...but the CA regulation is still way more complicated and unworkable relative to the AZ model]


Dear Mr. Rowland,

I am an ecological systems designer, and the author of three books on greywater.

It seems that the main stated argument against California greywater standards following the lead of Arizona, New Mexico and Texas into the 21st century is public health concern. But...

1) Greywater has hundreds of times fewer pathogens than combined sewage. Logically, greywater systems could be hundreds of times less effective at sequestering pathogens from people and still be no more dangerous than septic or sewer systems. (average of values from calculations, U of AZ study--see for complete list of citations and calculations)

2) The past several decades of greywater prohibition have inadvertently resulted in the construction of a rather large number of unpermitted systems. The quantity of those systems is vast (eight million in the US, 1.7 million in California) and the experience long term, going back to the founding of the country. (Soap and Detergent Manufacturer's Association Graywater awareness and usage study (pdf), a nationally representative sample of 61,377 households; 13.9% of which were using greywater in CA, the highest proportion of any state).

This has in effect served as a large-scale, long term, and fairly conclusive experiment on the epidemiological danger from unregulated greywater reuse.

There have been approximately a billion greywater system-user-years of exposure in the US since 1950, plus exposure to guests and neighbors. If one greywater user in 100,000 got sick and mentioned why, there would be 10,000 incidents on record.

In fact, no record of a single documented instance of greywater-transmitted illness has been recorded in the US, according to the CDC. (By comparison, approximately 20,000 people were struck by lightning over the same time period).

It is certain that greywater risk is non-zero. It is possible that the risk from the average greywater system could be low enough to be unnoticeable in the background risk, yet still be of concern in the aggregate.

However, with such a vast quantity of systems, there must be outlier systems that are several standard deviations riskier than the average that still number in the thousands. If even these have escaped notice, the implication is that the inherent risk must be very low indeed. (One unfortunate Californian has been struck by lightning on seven occasions. That there is no analog for greywater incidents is quite instructive).

Of the 12 illnesses identified by WERF as potentially greywater-transmittable, 9 are reported to the CDC by legal mandate. Reportable illnesses have been tightly tracked by all levels of our public health system since 1925. This serves as a more tightly run subset of the general greywater experiment. There are over 100,000 instances of these 9 reportable sicknesses, per year, or several million total. If greywater were a significant transmission path, tens of thousands of alarms in the reportable illness system would have put public health officials on the track decades ago.

The absence of reports of greywater-transmitted illness fits with the simple logic of point 1, and lends support to the Arizona/ New Mexico/ Texas regulatory approach. This holds that permits and inspections are not necessary for simple greywater systems (the people of California seem to agree: only one system in eight thousand is permitted).


Unless HCD can:

A) Prove that greywater systems are dangerous, in light of a billion system-user-years of real-world experience to the contrary

B) Prove that tight regulation (which deters licensed professionals but not homeowners) is better for public health than realistic guidelines that professionals would follow to improve the state's stock of systems

C) Produce a risk assessment that shows that in a world which may be out of usable water within our lifetimes, rigorous permitting of greywater systems is a priority use of regulatory and citizen resources


Please shift from the failed UPC-style approach to the state-of-the-art Arizona/ New Mexico/ Texas tiered approach to greywater regulation.

A slightly improved version of the Arizona code that is a suitable starting point for new California tier 1 standards can be found at:



Art Ludwig

Ecological Designer

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Call for Tiered Greywater Standards

Re SB 1258: Support for Reality-Based Greywater Standards


Mr. Rowland,

I am writing to support the adoption of a new California greywater standard that uses a tiered approach; more regulatory oversight of greywater reuse scenarios that entail more risk, and little or no regulatory oversight of systems that have little or no actual risk.

This is the state-of-the-art approach that is spreading regionally, in Arizona, New Mexico, Texas, and Malibu.

These jurisdictions recognize that a simple greywater system is beneath the threshold at which regulatory scrutiny is productive.

They all allow simple, tier 1 greywater systems that meet a short list of reasonable requirements to be installed without applying for a permit.

For tier 2, systems that don't meet these requirements, a permit application is required.

For tier 3, high flow systems, full-blown engineering is required.



  1. Greywater is about 1000 times less dangerous than combined wastewater.
    So, greywater systems can be about 1000 times less effective at sequestering pathogens from people and still be no more dangerous than septic or sewer systems
    Greywater has three or so orders of magnitude (1000x) less pathogens than combined sewage. (All references follow below)

  2. A billion system-years of experience with systems made poorly, under prohibition, without professional or regulator guidance in the US, has unintentionally proved that greywater systems are exceedingly safe in practice.
    There are 8,000,000 unpermitted greywater systems in the US; nearly 1,700,000 of them are in California. Yet even in this totally uncontrolled, health nightmare scenario (the status quo), people are not getting sick because of point #1: there has not been a single documented instance of greywater transmitted illness in the US. The risk is surely non-zero, but it can't be very high at all or some blip would have shown up on the radar of our world-class public health system.
    This is simply a colossal sample size. If greywater opponents' calculations were anywhere near true, there would be so many sick people that you'd notice them even if you weren't looking. If, for example, one out of one thousand greywater users got sick from a year's use of greywater and said so, we've have recorded a million cases since 1950.
    In reality, in twenty years of wrangling over greywater rules, no opponent has been able to produce a single documented case of greywater-transmitted illness in the United States.
    This supports the simple, obvious logic of point #1. The risk is surely non-zero, but it can't be as much as the risk of being hit by lightning, say (400 victims a year), or some blip would have shown up on the radar of our world-class public health system by now.

  3. The current CA greywater code is so unrealistic and so widely ignored it is at best ineffective and at worst undermines the credibility of codes.
    Greywater laws such as UPC chapter 16 make it very difficult to make anything but greywater systems that are
    -difficult to design
    -expensive to
    -hard to use
    -disgusting to maintain
    -integrate poorly with other systems,
    -and are more expensive than wasting water

    ince the adoption of its greywater law in 1992, only a few hundred systems have been permitted in the the entire state of California, about one in ten thousand systems, or a one hundredth of one percent compliance rate.
    If 9,999 people out of 10,000
    think the code is not worth following, perhaps the code is wrong, and not the vast majority of civil society?

  4. The only group of people deterred by the current prohibition of simple greywater systems is building professionals. Realistic greywater guidelines would allow professionals to install simple greywater systems, improving the average system quality over time.
    Common sense suggests that better results than the California status quo will be obtained by the Arizona/New Mexico/Texas/Malibu approach. There, regulators recognize that simple greywater systems are not in the same class as septic tanks. Greywater systems are to septic tanks what small sheds are to big houses. That is to say, the regulatory and citizen effort to get soil tests, site plans, permits, engineering and inspections for simple greywater systems would be better spent on other things.
    There, regulators recognize the public health benefits from allowing professional plumbers, builders and landscapers to work on simple systems without the threat of losing their licenses, and that public health is not served by forcing homeowners to hide their systems out of reach of positive influence by regulators or professionals.

  5. Well-designed, very simple and inexpensive greywater systems are a cost-effective way to reduce the health and environmental threats from failing septic tanks and overloaded sewage treatment plants.
    Greywater systems leverage the high inherent capacity of plants and soil to purify wastewater from their strongest point: the top foot of soil, which has 90% of the beneficial bacteria and plant roots in the soil. Where septics are marginal (the water is applied below most of the purification capacity), greywater can improve treatment.

  6. Under currently permitted/ mandated practices, the earth's life support systems are being degraded at an accelerating rate.
    The data on this are becoming so compelling that the judiciary is starting to take note in case law. Regulators are on more and more solid ground to embrace alternatives, and less solid ground to mandate systems that endanger the long term ability of the planet to support human life.


The California Greywater Working Group has the skill set necessary to take the model codes from Arizona, New Mexico and Texas, and the process in Nevada, and craft a consensus state-of-the-art model code that would not only be optimal for California, but would be widely emulated worldwide.


At the first meeting of the Stakeholders group on February 25th, the decision should made to scuttle UPC chapter 16 and take the this course of action immediately above; adapting the AZ/NM/TX approach to California.





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Greywater safety references

Latest greywater data and calculations spreadsheet (xls), with citations. Note that as we refine the data the numbers in the spreadsheet and text may get out of sync; the spreadsheet represents our latest, most refined take.

Hats off to researcher Ed Hachfeld for the CDC reportable illness research and analysis.

  1. Greywater is orders of magnitude less dangerous than combined sewage.
    Reported values for greywater fecal indicator bacteria vary widely. The use of indicator bacteria to gauge greywater pathogens is extremely suspect. For example, in the Arizona Water CASA greywater study, fecal coliforms were 822 mpn for greywater w/o kitchen sink water, and 8400 with kitchen sink water. Unless people in Arizona have a very unusual way of using kitchen sinks, these values are reflecting something other than feces going into the water; most likely, indicators breeding in the plumbing. Whether pathogens breed also is an open question.

    The average value for the Arizona study was just under 5000 mpn for fecal coliform indicators. A typical value for combined sewage is 3,000,000; six hundred times as much.

    The WERF study shows some researchers finding 100 mpn while others found three times as many fecal coliforms in greywater as raw sewage (10,000,000 mpn). That there could be this much feces/ pathogens in greywater fails the credibility test in two ways:

    a) With a billion system user years of exposure, lots of people would be getting sick if these high indicator levels corresponded to levels of pathogens
    b) A reality check on the use of indicators is to calculate, for example, the amount of feces you'd expect in greywater if, say, people showered instead of wiping after using the toilet: 1000 mpn, or 1/3000th as much as raw sewage. (If people wipe, the traces of feces remaining would yield more like 50 mpn, or 1/60,000th as much). See: Water indicator bacteria levels (xls).

    Several studies have demonstrated that indicator organisms can persist and even multiply in stored graywater due to available nutrients and/or biofilm formation which enhances pathogen survival (Rose et al., 1991; Ford et al., 1992). Moreover, pathogens seeded into graywater are capable of reproducing during graywater storage. Salmonella typhimurium and Shigella dysenteriae, for example, survived several days when seeded in graywater at pH 6.5 and 25C (Rose et al., 1991). This raises the question of whether the typical concentrations of indicator organisms used assess the human health risk with respect to fecal contamination in wastewater are a meaningful measure of the actual human health risk posed by graywater. Many researchers think not. Ottoson et al. (2003) indicated a potential for over-estimation of the fecal lead using Coliform as bacterial indicators for enteric pathogens. The conclusions encourage use of fecal enterococci as a guideline if one must be used. But the actual risk to human health associated with graywater reuse is not known because studies have shown that indicator bacteria can actually multiply while the graywater is in storage, while studies of actual pathogenic organisms have found that the pathogen counts decrease rapidly over time.

    from WERF study: Long-Term Effects of Landscape Irrigation Using Household Graywater (pdf), table 3.1, Arizona Water CASA greywater study
  2. Seven percent of Americans currently have greywater systems; in California, 13.9%. Soap and Detergent Manufacturer's Association Graywater awareness and usage study (pdf), p14: A quarter page mail survey was sent to a nationally representative sample of 100,000 households, utilizing the Home Testing Institute monthly consumer omnibus, Insta-Vue...Total usable returns were 61,377 at a return rate of 61%... Greywater usage over 50% in Santa Barbara, 1990: Oasis Design door to door survey of a few dozen houses in Hidden Valley and San Roque neighborhoods. Oasis Design direct observation in Northern California rural areas, etc.: Greywater usage 15%. Arizona WERF study: Long-Term Effects of Landscape Irrigation Using Household Graywater (pdf).

    303,824,640 population of US, 2008
    x 7% US average for households that have greywater diversion systems, from Soap and Detergent Association (SDA) Graywater awareness and usage study (pdf).
    =21,268,000 greywater users
    /2.6 average people/ house (US average, WERF study: Long-Term Effects of Landscape Irrigation Using Household Graywater (pdf)
    =8,180,000 illegal greywater systems

    Two million ± illegal systems in CA
    36,457,549 population of CA, 2006
    x 13.9% US average for households that have greywater diversion systems, from Soap and Detergent Association (SDA) Graywater awareness and usage study (pdf).
    =5,068,000 greywater users
    /2.6 average people/ house (US average, WERF study: Long-Term Effects of Landscape Irrigation Using Household Graywater (pdf)
    =1,949,000 illegal greywater systems
    (this assumes the proportion of greywater use has not changed significantly since 1999. Using the 1999 population of 33,418,380, the number of illegal systems was 1,786,598).

    System user years-CA
    This is a back of the envelope-type calculation; the point is still valid if it is off by a factor of two.
    5,000,000 greywater users 2009, 13.9% (see above)
    2,000,000 greywater users 1950, 20% (estimate) of 10,000,000 1950 population
    3,500,000 greywater users average for 60 years =
    210,000,000 system-user-years of greywater exposure, not counting neighbors and visitors.

    Note: the proportion of households with greywater systems was near 100% for the first few centuries in California. The first documented greywater system in Santa Barbara is visible today in front of the mission. It is a huge stone laundry wash station, with a dozen or more stations, that fed a cornfield where the lawn is today.

    System user years-US
    This is a back of the envelope-type calculation; the point is still valid if it is off by a factor of two.
    21,000,000 greywater users 2009, 7% (see above)
    15,000,000 greywater users 1950, 10% (estimate) of 150,000,000 people
    18,000,000 greywater users average for 60 years =
    1,080,000,000 system-user-years of greywater exposure, not counting neighbors and visitors.

    The other two million plus systems have been built poorly, with lack of professional installation help or useful official guidance.
    Personal communication with myself. We're like the greywater doctors for the world; we have been getting frank confessions from greywater users on a daily basis since 1990. We've sold something like 100,000 greywater books worldwide. By the most generous estimate, myself and other CA greywater "professionals" (defined here as someone who has made more than their own illegal system) have helped a lot less than two million households. So, it's safe to assume that most of these systems are suffering from severe design information deficit.

    Yet, even in this worse case health nightmare scenario (the status quo), people are not getting sick because of point #1. Anti-greywater zealots have been asked for twenty years to show us the bodies, and in twenty years have not been able to come up with one documented instance of greywater-transmitted illness in North America.
    Here's an example of the kind of lengths you have to go to to get a theoretical 50% chance of greywater-transmitted illness (this was crafted by a health department official during the greywater regulation war of the early 1990s:

    "According to my calculations, someone is playing golf on grass irrigated with greywater, would have a 50% chance of getting hepatitis"

    I asked for the calculations and assumptions, which I then dissected. Here they are:

    -100% of pathogens on greywater stick to the surface of the grass, none follow the water into the soil.
    -The golf ball picks up 100% of the pathogens in a swath 50 yards long and its full diameter wide.
    -The golfer gets 100% of the pathogens from the ball to their hand.
    -The golfer gets 100% of the pathogens from hand to mouth.
    -The shower water has 1,000,000 fecal conform bacteria per 100 ml in it.

    I could see that these were pretty conservative (OK, well, outlandish) assumptions, with the exception of the last one, which I couldn't understand at all.

    Some research showed that this is something like a fifth of what you might find in raw sewage. Is that reasonable for greywater? Who the hell knows? How do you convert "1,000,000 mpn fecal coliform bacteria to a unit that a non-microbiologist can understand, like ppm? A bunch more research formed the basis for our Fecal coliform counts page, which consistently ranks high for a search on fecal coliform+whatever.

    Well, it turns out that these weird units (by one of those funny coincidences) equate with parts per BILLION of feces, and hidden behind these barrier to entry/ understanding units was the most preposterous assumption: The shower water has several grams of feces in it. (For the metric-challenged, that is several hundred butt wipes). This would be a high reading for bidet drain water. For shower water, that's high by a factor of several hundred, at least in our house!

    NOTE: Dog poop is strewn all over the landscape much more widely and even less consciously than greywater. If dog poop were included on this graph, the upper end of the scale would twenty two times higher. The only other bar that would even be visible would be the toilet water one. With our bodies adapted to this scale of constant fecal assault, it is no wonder that the inconsequential threat from greywater vanishes in the statistical noise.

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  3. Only a few hundred systems permitted Santa Barbara, California is ground zero for greywater legalization in the US. I have been personally involved in the permitting of two systems, on in the city, one in the county. According to personal communications with city and county officials, less than 20 systems have been permitted in the city and county combined, total, from 1989 to 2009. My two systems are 10% of the permitted installations in the greywater capital of the US! ReWater Systems has permitted under 100 systems, they are the only greywater system supplier to survive from the early 1990s to the present day. The balance is a generous estimate for other suppliers.
    200 ± permitted systems/
    2,000,000 unpermitted systems
    =one in 10,000 systems permitted, or 0.01% compliance rate

  4. Homeowners not deterred by tight regulation, professionals deterred Based on my own experience of nearly thirty years, I'd estimate that fewer than 10% of the public have qualms about ignoring unreasonable greywater regulations. Conversely, I often get complaints that homeowners cannot get licensed professionals to help them with greywater systems due to the latter's concern about their professional status and license. I think that few people would argue that a plumber or builder—anyone who's done more than one system of their own—is likely to do a better job than an unaided homeowner.

  5. Well-designed, very simple and inexpensive greywater systems can reduce the health and environmental threats from failing septic tanks and overloaded sewage treatment plants
    Logical inference from data on sewage system failure, septic system performance, UPC appendix K separation requirements, variation of soil purification capacity by proximity to the surface; see Treatment vs application depth-pdfSewers & water quality, The World Health Organization on pollution plumes from dry pit toilet (GIF graphic)
    The World Health Organization on pollution plumes from pit toilet in groundwater flow (GIF) Removal rates of land treatment facilities (PDF)

  6. The earth's life support systems are being degraded at an accelerating rate. Worldwatch institute, National Geographic, EPA, etc. etc.
    The data on this are becoming so compelling that the judiciary is starting to take note in case law.
    Activists who painted the name of a politician in huge letters on the smokestack of a new coal-fired generator in England that he'd subsidized recently got off the hook for tens of thousands of pounds of clean up costs using the English version of the necessity defense.
    Presented with the current evidence on global warming, the Judge agreed that the clear and present danger was such that this action was legally protected in a way analogous to someone trespassing and damaging property in order to save a trapped child.
    This has sent some shock waves out. See Cleared! Jury Decides That Threat of Global Warming Justifies Breaking The Law.
    The threat of global warming is so great that campaigners were justified in causing more than £35,000 worth of damage to a coal-fired power station, a jury decided yesterday. In a verdict that will have shocked ministers and energy companies the jury at Maidstone Crown Court cleared six Greenpeace activists of criminal damage.
    Jurors accepted defense arguments that the six had a "lawful excuse" to damage property at Kingsnorth power station in Kent to prevent even greater damage caused by climate change. The defense of "lawful excuse" under the Criminal Damage Act 1971 allows damage to be caused to property to prevent even greater damage - such as breaking down the door of a burning house to tackle a fire.
    Regulators that are tardy in the shift towards more ecologically sustainable systems may well face lawsuits for reckless, negligent endangerment of human life You want to be the one to find out the hard way?

    Obsessive fear of theoretical greywater cooties while the state drains of groundwater, empties of surface water, dries up and blows just so last administration. The prudent course of action is now the same course of action that you could explain to your grandchildren with pride. See Legalize sustainability for more on removing institutional barriers to sustainability.


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Suggested Changes

Address Dismal Participation Rates

Unrealistic laws have poor participation rates. Santa Barbara, for example, has issued approximately 10 permits for grey water systems in the twenty years between 1989 and 2009 (!)

And this is in the birthplace of legal greywater. A place where our own door to door survey in 1990 (the only survey of greywater use rates that I'm aware of) indicated that during this severe drought over half of households in some areas, or about 50,000 Santa Barbarans were using grey water!

Something is clearly wrong here. If builders of 499 out of 500 structures refused to get permits, you can bet there would be investigation of all aspects of the permitting system, standards, and people's practices.

This dismal greywater permit participation rate is an issue for several reasons:

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Why do health authorities think people will get sick from greywater?

  1. Greywater has indicator bacteria and pathogens in it.
  2. Greywater systems provide less insulation from these bacteria than septic systems.

So why aren't people getting sick from greywater? Two main reasons:

  1. Greywater isn't particularly dangerous. Greywater has drastically less pathogens in it than combined sewer water-about a thousandth; Water indicator bacteria levels (xls). Average greywater has about the maximum level of bacteria allowed for boating and fishing. Systems that process toilet water, which contains 99.9% of the pathogens, are critical. Systems that process greywater are a thousand times less critical. If no more greywater slops onto people from their irrigation systems than if they were boating or fishing in greywater, statistically, you wouldn't expect them to get sick. (No, I'm not proposing greywater water parks, I'm just trying to explain the seeming anomaly of no one getting sick from greywater systems).
  2. Greywater systems don't add a significant new route of exposure. When you are eating off the same dishes, breathing the same air, using the same doorknobs, sitting on the same chairs, playing on the same dog-poop littered lawn, shaking hands, hugging, kissing, etc, the added health risk from having your fruit trees irrigated with the laundry water is utterly insignificant.



Apportion Regulatory Effort Rationally Based on Low Reported Risk

The actual, reported risk of greywater systems in the US, so far as we've been able to determine, is zero.

There is a long history of surface greywater reuse, with systems far, far less safe than those specified in the current law, which has not produced a single documented case of greywater-transmitted illness in the United States. In Australia, greywater is legally distributed through sprinklers with 6’ throw.

The City of Los Angeles Greywater Pilot Project showed that greywater makes a negligible contribution to the pathogens in soil, while dog feces, for example, contribute a significant amount of pathogens to the suburban environment. Even the worst illegal greywater systems don’t stand out among myriad sources that besiege our bodies with pathogens in the course of ordinary life. The actual health threat is plenty small enough to include ecological and practical considerations on equal footing with public health considerations.

It is my belief that simple greywater systems are to septic systems what under 120 ft2 sheds are to houses. Most jurisdictions allow small sheds to be built without permits, provided they meet guidelines as to height, setbacks, and other restrictions.

It would be a waste of citizen and regulator resources to inspect every woodshed, tree house and chicken coop. There is a recognition in the code that certain classes of structures are beneath regulator attention.

The same is true of greywater systems. Since people are not getting sick from them, why waste regulatory energy on them?

Rational allocation of regulatory resources is the clear trend for greywater regulation. Arizona, New Mexico, and Texas have all passed tiered greywater regulations, the simplest tier of which do not require a permit application.

California may not be ready to take this step for all systems, but I strongly suggest it take this step for laundry-only greywater systems.

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Arizona-Style Lowering of the Permit Bar for Laundry-Only Greywater Systems

One way of getting the participation rate off the ground and gaining some credibility as a source of guidance for greywater users would be to follow Arizona, New Mexico, and Texas's lead in the sensible regulation of greywater by providing a statewide permit for simple, laundry-only greywater systems that met reasonable guidelines (or allowing them without a permit, like small sheds. Or, allowing local jurisdictions to pursue reduced permitting and regulatory oversight for laundry only systems, as each local jurisdiction sees fit).

Relative to the status quo (hundreds of thousands of households doing this very thing outside the regulatory system), this can only improve public health and safety. Here's the rationale for handling laundry water differently:

If you can think of a disadvantage to this change relative to the status quo, please  Email us .


Info on Laundry to landscape , a new design for the simplest, most ecological laundry only system currently known, which can be made easily from off-the shelf components.

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Address as Many as Possible of These Long-standing Issues with the CA Greywater Law

Needed Improvements to CPC/UPC Greywater Law (from our  Builder's GW Guide-book, edited for the SB1258 round of improvements.

General Suggestions

Wherever appropriate, require achievement of performance goals (e.g., ecologically and biologically safe treatment of wastewater), with explicit designs as options, rather than specifying mandatory techniques to be used. The field is evolving too fast for specific designs to be relied on exclusively.

Be more realistic about the quantitative health threat from greywater systems. (see above).

Regarding indoor greywater reuse, require achievement of performance goals and encourage cascading. I personally believe that there is no currently available system which is economical and ecological for indoor reuse. However, this was the case with outdoor systems when the first greywater law was passed. I think it would be a mistake to kill the nascent indoor greywater reuse industry by making impossible regulatory barriers. I suggest setting out reasonable performance criteria and leaving it at that. The economic viability barriers will keep this sector very small for the foreseeable future.

Specific Suggestions

Base code: Start with Appendix G, the currently adopted greywater language in California, unless Chapter 16 2009 version is demonstrably better. In it's 2007 version it is a huge step backwards. (If this is not done, the list of needed changes is much longer, as all the problems remedied in the 1997 revision would be back on the to do list...see: UPC&CPC improvements)

Use the latitude mandated in SB1258 17922.12. c) 6, to use Arizona's greywater law as the base template for laundry only systems.

G-1-f Allow reduction in size or elimination of septic/sewer system if the alternative waste disposal system is capable of handling all wastes as well or better, at the discretion of the Administrative Authority. There are sites and regions where currently mandated treatment technologies cause more ecological and health problems than proven alternatives. Regulators are allowing this in practice, and they should have clear guidelines.

G-7 Allow greywater systems in areas with high groundwater at the discretion of the Administrative Authority. A proper greywater system design can provide better treatment and protect groundwater better than currently mandated systems. A specific provision requiring that a given amount of soil separate greywater from aquifers in Karst formations would be reasonable.

G-7, G-8, Table G-2, Table G-3 Explicitly allow reduction in system design loads with water-conserving fixtures. Projects with aggressive conservation shouldn’t be penalized by having to install the same size system as the worst water hogs. The current language allows local discretion in this area but the possibility is not mentioned explicitly.

G-8-b Allow greywater systems across a wider range of percolation rates, at administrative authority discretion. Greywater systems are safer at higher and lower percolation rates than septic systems, so it is foreclosing on the possibility of a real water quality and public health improvement to not allow the loading on septics to be reduced on a discretionary basis.

G-9-h Require below-grade tanks to be anchored against popping to the surface if conditions indicate this may be a problem. Unlike septic tanks, greywater surge tanks are often empty and experience tremendous buoyant lift under saturated soil conditions. This would protect consumers.

G-11-a-2 Modify the requirement that “system design shall be such that emitter flow variation shall not exceed plus or minus 10%” with the phrase “in instances where greater variation could result in flows high enough to produce per emitter ponding in the soil in question.” Greywater systems do not all require this level of precision.

G-11-a-6 Change wording from “pressure at pump shall not exceed 20 psi” to “pressure at any emission device shall not exceed 20 psi.” The current wording effectively precludes irrigation with adequate pressure at a location significantly higher than the pump.

G-11-a-5, G-11-b-2 Explicitly allow greywater to be distributed and emitted through lines covered by mulch at the discretion of the Administrative Authority. This would be a great step forward. This would support local discretion in greywater regulation, which is generally agreed to be a goal.

G-11-b-1 Allow smaller diameter pipe, half-pipes in Mini-Leachfields. Or better yet, delete mini-leachfields as a specific system (since few or none have ever been built, or ever will be built) and put in general performance guidelines for non-drip systems.

Table G-1 Allow installations on steeper slopes where environmental conditions are such that the water will not surface.

Table G-2 Take into account the higher LTAR of mulch basins by halving the required infiltration area for systems that use them.

Explicitly describe Laundry to Landscape to Mulch Basins, Branched Drain to Mulch Basins, Infiltration Beds, Leaching Chambers, and Box Troughs (see  Create an Oasis with Greywater-book) as allowed system examples.

Figures: Show a greywater surge tank (usually a 55 gal drum) rather than a sewage ejector pump tank in UPC figures. Include a note that the running trap is only required in the rare instance that the fixtures lack traps.

Eliminate the requirement for backwater valves. These are an unnecessary expense and a maintenance issue. If they are not needed to prevent blackwater from pouring out the shower drain, they shouldn't be required to prevent blackwater from backing into the greywater system. There is likely to be more exposure to people unclogging the backwater valves than is avoided by having them.

Allow greywater surge tank to be vented back through the house vents (as is done with all septic tanks and sewers) as an alternative to a vent at the tank. A vent is necessary; a dedicated vent is not.

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Make a Finding to Clarify that SB 1258 Allows Local Jurisdictions to Adopt More Liberal Regulation of Greywater Based on Local Conditions

California Health And Safety Code Section 17958.5

Except as provided in Section 17922.6, in adopting the
ordinances or regulations pursuant to Section 17958, a city or county
may make such changes or modifications in the requirements contained
in the provisions published in the California Building Standards
Code and the other regulations adopted pursuant to Section 17922 as
it determines, pursuant to the provisions of Section 17958.7, are
reasonably necessary because of local climatic, geological, or
topographical conditions.
For purposes of this subdivision, a city and county may make
reasonably necessary modifications to the requirements, adopted
pursuant to Section 17922, contained in the provisions of the code
and regulations on the basis of local conditions.


Consider Use and Regulation of Greywater in Other Jurisdictions

SB 1258 c (6) Consider the use and regulation of graywater in other jurisdictions within the United States and in other nations.

Malibu, CA

Malibu p. H1-2 (Handbook 1, page 2) , top of second column: it appears that only the two more complex of four types of greywater systems require an inspection

p. H3-6, H3-19 H7-1, H7-8, "mulched watering moats"

H7-5 "for single fixtures, a soil can be determined by homeowner (Handbook 5). For two fixtures, the City Health Specialist may allow the homeowner test. For more than two fixtures, a professional soils analysis is required"

Mendocino, CA

Greywater definition follows the EU, Australia:

Sec. 18.23.240 Greywater.

"Greywater" shall include all domestic waste water obtained from the drainage of showers, bathtubs, kitchen sinks, laboratories, and laundry facilities, exclusive of water utilized for the transport and disposal of body eliminations. (Ord. No. 3343, adopted 1981.)


Tiered regulation of greywater,


Montana's 2007 greywater law HB 259 follows the European Union and Australian definition of greywater, which includes kitchen sink water:

Section 1. Definitions. As used in this part, unless the context indicates otherwise, the following definitions apply:

(1) "Gray water" means wastewater that is collected separately from a sewage flow and that does not contain industrial chemicals, hazardous wastes, or wastewater from toilets.
   (2) "Gray water reuse system" means a plumbing system for a private, single-family residence that collects gray water.


According to Regulators "must not require people to get a permit" (page 10).

New Mexico


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Department of Housing and Community Development to Publish Their Data Base and Assumptions

This suggestion is for the DHCD to publish (for example, on the web) the list of studies and assumptions that their conclusions are based on, so other stakeholders have ready access to the the same, common set of shared data. This should save time all the way around, and facilitate communication.

Research Needed

These are points where more data (or more official data) would facilitate regulatory support for greywater best management practices:

More California Greywater Law Revision Resources

General References, Studies

Greywater best practices how-to

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