Graywater Central supports the recommendation to update plumbing codes to require graywater-ready plumbing in certain construction situations.
During new construction, and in extensions and remodels where piping becomes exposed, it would make sense to require the installation of parallel drainage piping and appropriate diversion valves to enable the option of sending graywater out of the house. Exemptions could be made for properties with high seasonal groundwater tables, heavy clay soils with limited infiltration capacity, or zero-lot-line urban infill sites without adequate permeable ground area.
It would be cheap and easy to install these secondary pipes and cap them off for later use. If the pipes never enter service, the additional work and expense will have been minimal, while the potential benefits would be maximal.
This 3:24 video briefly illustrates the ease with which such work can be done:
As you see in the case of core drilling versus pre-installed sleeves, if this work had been done when the foundations were poured in the first place, even what was done here would have been faster, cheaper, and easier.
Graywater retrofits by enthusiastic customers are routinely done, despite costs and challenges. Nevertheless, post-construction retrofits represent only about 1% of existing buildings each year. This proposal would greatly expand opportunities for water savings by making minor adjustments to standard practices so that the option becomes the norm.
The International Association of Plumbing and Mechanical Officials (IAPMO) creates safety standards for plumbing and mechanical products and systems. However, under existing law, governments at all levels may choose to either follow, modify, or ignore these standards.
California Senate Bill 518 Chapter 622 of 2010 was about requiring the California Building Standards Commission to adopt non-residential building standards for graywater systems for indoor and outdoor use. But it left open the choice to actually install such systems.
California Senate Bill 966 of 2018 also had to do with clarifying and adopting standards for using reclaimed water, as well as requiring local jurisdictions to be involved. It too left open the choice whether to install reclamation systems or not.
The new proposal does not address graywater standards. It recommends mandating the installation of graywater-ready piping.
Cities Already Leading on Graywater-Ready Codes
Graywater Action published a Graywater-Ready Model Ordinance in 2016, including detailed drawings and diagrams. The stated purpose is “to lower the costs and barriers for future graywater system installations.”
The Central Coast Greywater Alliance updated it in 2020 as Drought-Ready Construction Model Ordinance. The stated purpose is “to lower the costs and barriers for future installation and future use of alternate water source systems for non-potable uses by preplumbing buildings during construction or during certain remodels that expose supply or drainage piping.”
Tucson Arizona is a leader in the field, having decided back in 2008 via Ordinance 10579 that all new single family homes and duplexes must include plumbing for future graywater distribution.
Los Angeles joined the game in the dry year of 2016 with LA Green Building Code Section 4.305.2, which requires that “piping shall be arranged to permit the discharge from the clothes washer, bathtub, showers and bathroom/restroom washbasins to be used for a future graywater irrigation system(s).” However, they exempt additions and alterations that use the existing building drain.
Why Graywater-Ready Plumbing Needs to Become Mandatory
Droughts drag on longer and stronger. Wildfires rage hotter and larger, and more frequently. Population growth creates all kinds of ramifications that impact water demand, water shortage, and water crisis. All are interlinked. Better water use is not only wise planning for the future, it’s wise action in the present.
How Population Growth Is Straining Water Supply
Despite fluctuations in rate of growth, population in the USA continues to rise. A favorite indicator in the news of a favorable economy is New Housing Starts, the more the better.
The current water use model is to import vast quantities, expend energy to clean it to a high degree, use it once, and discard it as “waste,” expending still more energy to clean it on the way out.
Population growth does not make this situation any easier. In fact, The U.S. Department of the Interior has proposed drastic water-use cuts among states in the Colorado River Lower Basin to take effect when current agreements expire at the end of 2026: “The federal provisions include cuts of up to 40% to the shared supply of California, Arizona and Nevada in the lower basin.”
Because the affected states have been unable to come to any new agreements, “The federal government plans to roll out more detailed management plans every two years if the states continue their impasse.” (CalMatters.org, August 5, 2026)
Water restrictions introduced in Los Angeles in 2022 were already unprecedented, and an operations manager at the Metropolitan Water District said that going forward, “There’s a good chance it’ll be as bad as it’s been, and there’s a reasonable chance that it’ll be worse”.
Requiring graywater-ready plumbing would bypass the allocation fight altogether by maximizing the usage of water already coming in, and reduce demand for further water delivery.
Drought Is Getting Worse, Not Better
Regardless of the controversy over the causes of climate change, you only have to look at drought statistics over any number of recent years to realize a better use of water would be wise. Global drought severity has increased 40% since 1981. In the 5-year period 2018 to 2022, global areas in drought have expanded by 74% on average compared with 1981–2017.
Since 2000, the [Colorado River] Basin has been experiencing one of the worst multi-decade droughts of the last 1,200 years … The average streamflow from 2000 to 2025 is dryer than any 26-year period in the reconstructed paleo record developed by Meko, et al, which extends back to 760 AD.
The Basin is experiencing increased aridity due to climate variability, and long-term drought and low-runoff conditions are expected in the future.
–US Bureau of Reclamation
Making matters worse, Colorado restricts home rainwater harvesting because under the Priority System of water rights, industrial farmers who got there many decades ago can claim ownership of the rain falling on your roof. They have the legal right to demand that every drop of rain flow down into the rivers for them to extract for their own large-scale monoculture practices. The desperate need to own the rain is partly the result of the severe over-allocation of the major rivers in the American West.
Cities are built to shed water, not absorb it. Replacing vegetation with continuously expanding pavement creates heat islands.
Urban creeks lined with concrete move water away as quickly and completely as possible. The thinking is flood control, but combined with over-drafting wells for both city and agricultural use, the result is depleted aquifers and subsiding land.
A 2025 study published in ‘Resources, Conservation, and Recycling Advances’ … notes that groundwater depletion is now a ‘rapidly evolving crisis’ in the United States. The New York Times reported record levels of water loss in 2023, and 25 of America’s largest population centers are literally sinking as the aquifers beneath them are over pumped.
–EpicCleanTec.com
Subsidence causes irreparable damage because it can close aquifers forever. An aquifer is not a big underground cave with a lake – it’s the ground as a saturated sponge. When over-drafting wells pulls water from deeper and deeper down, the ground above settles, compressing all the small spaces in the sponge until it can never hold water again.
The easier it is to put water back in the ground, and the more times water can be used before it gets there, the more we can turn things around and head in a better direction.
The Link Between Wildfire Risk and Water Scarcity
NASA satellites have detected that over the last 21 years, extreme wildfires have become more frequent, more intense, and larger. The US Forest Service studied 35 years of weather data and foud that parts of the Western United States, Mexico, Brazil, and East Africa now have fire seasons that are more than a month longer than they were 35 years ago.
One of the traps of drought is that municipalities necessarily restrict water usage. But that leads to even drier vegetation, which in turn increases fire danger.
If good plans and practices bring all appropriate drains online, graywater can account for up to 75% of the “wastewater” output of houses. Simple systems can passively irrigate surrounding vegetation, contributing to keeping it green year-round in fire-prone areas.
The more complex pump-filter devices (see our AquaLoop article) can clean graywater enough to be used safely in overhead-spray lawn watering, as well as back in the house both to wash laundry and to flush toilets.
Putting lightly-used water to additional use can help keep a green safety buffer around buildings without breaking water restrictions. Using the leverage of forward-looking building codes can steer us away from more Eaton, Palisades, and Lahaina fires.
Can Graywater-Ready Plumbing Really Stop a City from Burning?
Modern civilization is based on the idea of humans conquering nature. It’s the height of disingenuousness to claim helplessness when the goal becomes repair.
Working individually, we can save our own homes. Working collectively, we can save our neighborhoods. Working on a large enough scale, then we can turn conditions around.
A Small Code Change with a Big Water-Saving Payoff
Repairing the hydrologic cycle would put water back into the ground after it’s used. Requiring the drainage pipes to make it possible expands exponentially the possibility that it will happen.
It’s wise planning for the future, and smart action for right now.