Greywater Laws for Gardens and Farms
What counts as greywater?
| Type | Examples | Usual treatment in garden rules |
|---|---|---|
| Greywater | Water from washing machines, bathroom sinks, showers and baths. | May be reused for irrigation under state and local rules. |
| Kitchen water | Water from kitchen sinks and dishwashers. | Often excluded or treated more strictly, because of grease and food waste. Arizona’s guidelines exclude it. |
| Blackwater | Toilet water and water contaminated with feces. | Never used on gardens; goes to sewer or septic. |
| Stormwater and rain | Water from roofs and the ground. | Separate rules. See rainwater harvesting laws. |
Is greywater legal for gardens?
There is no single federal rule. States and local governments set the rules, usually through the plumbing code and the health department. States generally fall into three groups:
- Permit-free tier for small systems: the state allows simple, low-volume systems without a permit if they follow performance guidelines.
- Permit required: any greywater system needs a permit, sometimes with a design and an inspection.
- Not clearly allowed: the code is silent or discourages reuse, and local officials decide.
Because these rules change, treat any list of states you find online as a starting point. Confirm with your state and local office.
| State | What the rule allows | Limits |
|---|---|---|
| Arizona | Residential greywater systems that follow the state guidelines and produce less than 400 gallons per day can be used without a permit, fee or inspection. | Water must stay on the property where it comes from. Kitchen sink and dishwasher water is excluded. Local ordinances can be stricter. |
| California | Laundry-to-landscape systems, which send washing machine water to plants, can be installed without a permit since a 2009 code change. | Other greywater systems generally need a permit. Follow the code conditions for the system. Check your local building department. |
These examples come from state guidance and summaries from advocacy and extension sources. They have not been checked against the current code text. Washington State and others also have small-system rules.
Greywater on a vegetable garden
Greywater can carry soap, salts, bacteria and viruses. The common safety rules in state guidelines and extension materials include:
- apply greywater to soil under mulch or through drip lines, not by sprinkler or spray;
- do not let it touch the edible parts of plants, and avoid using it on root crops and low leafy greens that touch the soil if the code says so;
- do not use it where it can pool, run off the lot or reach a neighbor;
- use plant-friendly, low-sodium and low-boron soaps, and no bleach, chlorine or borax products in the wash;
- do not store greywater; use it quickly, because it can turn foul and breed bacteria;
- keep it away from wells and surface water, and follow the setback distances in your code.
- Are you reusing washing machine, bath or shower water?If you plan to use kitchen water or toilet water, stop: it is excluded in many codes. Go to step 2.
- Does your state allow permit-free small systems?If yes, follow the performance rules exactly. If not, go to step 3.
- Does your city or county have stricter rules?Ask the building and health departments. Go to step 4.
- Does your lease or HOA permit changes to plumbing?Plumbing changes in a rental or HOA home may need approval. Go to step 5.
- Do you plan to grow food?Check the code and extension advice on edible crops. See irrigation water quality and food safety. If you sell produce, ask your state agriculture department about water used.
Permits, plumbers and inspections
If your state requires a permit, expect to submit a simple plan showing where the water comes from, where it goes and how far it stays from buildings, property lines and wells. Some codes require a licensed plumber for work on drains. Do not cut into a drain line without checking the code: an unpermitted connection can affect insurance and a home sale.
Checklist before you reuse greywater
- Read your state’s greywater code or guidelines and your local rules.
- Confirm that your source is allowed (laundry, bath or shower, not kitchen or toilet).
- Ask whether a permit, inspection or licensed plumber is required.
- Plan an irrigation method that puts water under mulch, away from edible parts and property lines.
- Choose plant-friendly detergents and do not use bleach or borax.
- Keep records of the installation and any permit.
- Ask your landlord, HOA or insurer if needed.
Frequently asked questions
Is greywater legal?
In many states, with limits. Some allow small systems without a permit, others require permits. Check your state and local rules.
Do I need a permit for a greywater system?
It depends on the state and the system. Arizona and California allow some small systems without permits; most other systems need one.
What is laundry to landscape?
A simple system that sends water from a washing machine to the landscape through a pipe or hose. California allows it without a permit under conditions.
Can I use greywater on vegetables?
Some codes allow it only with drip or subsurface application and not on edible parts. Check your code and extension guidance.
Can I use kitchen sink water in a garden?
Often not. Arizona excludes it, and many codes treat it as more contaminated than laundry and bath water.
How much greywater can I use without a permit in Arizona?
Under the state guidelines, systems under 400 gallons per day do not need a permit, fee or inspection if they follow the rules.
What soaps are safe for greywater irrigation?
Plant-friendly, low-sodium and low-boron soaps. Avoid bleach, chlorine and borax products.
Can I store greywater?
Usually not for long. It can foul and breed bacteria, so use it soon. Some codes forbid storage.
Can I use greywater at a community garden?
Often more regulated than a home system. Ask your local building and health offices and the landowner.
Does greywater reuse affect my insurance?
A permitted installation is less likely to cause trouble. Ask your insurer.
Can I use greywater in a drought?
Often yes, since it helps in a drought, but rules still apply. Check whether your city restricts outdoor use.
Is greywater harmful to soil?
Salts and soaps can build up over time, so rotate application areas and use low-sodium products.
Official sources
- Arizona Department of Environmental Quality, residential greywater reuse guidelines
- California Plumbing Code, greywater provisions (including laundry-to-landscape systems)
- Your state plumbing code and health department, and your city or county building department
- University extension publications on greywater irrigation
- Not checked for this page: the current text of the Arizona and California codes (examples come from guidance summaries), other states and local codes