AAC R18-9-D701: Arizona's Type 1 Gray Water Permit Rules

Gray water is gently used water from a home. It comes from bathtubs, showers, bathroom sinks, and clothes washing machines. It has not touched human waste or food waste. That last part matters. Water from the kitchen sink, the dishwasher, and the toilet is not gray water under Arizona's rule. Those sources carry too much grease, food, or waste to qualify.

The rule also excludes water from washing diapers or other soiled or infectious garments. It excludes water that carries hazardous chemicals, such as water used to clean car parts or wash greasy and oily rags.

The Type 1 general permit covers a private home that reuses less than 400 gallons per day of gray water. This is the tier almost every household falls into. There is no permit application to submit and no fee to pay. The permit applies automatically as long as the home meets every condition. Reuse above 400 gallons a day, or larger shared systems, fall under stricter Type 2 or Type 3 permits instead.

The core of the rule reads like this:

Gray water originating from the residence is used and contained within the property boundary for household gardening, composting, or landscape watering.

The permit comes with a list of best-management practices. Among the key ones:

• Keep it on your property. The gray water must stay within your own property boundary. It cannot run off onto a neighbor's land or into a street or wash.
• No spray irrigation. You may only apply gray water by flood or drip methods. Spraying it is not allowed, because spray creates a mist people can breathe in.
• No food-plant contact. Do not surface-apply gray water to food crops. The rule makes an exception for trees and shrubs whose edible part does not touch the water, which is why citrus and nut trees are the common choice.
• No standing water. Manage the flow so it does not pond on the surface. Mulch and careful watering help. Standing water breeds mosquitoes.
• Cover any storage tank. If the system uses a surge tank, keep it covered to block access and to deny mosquitoes a place to breed.
• Stay above groundwater. Keep at least a 5-foot vertical gap between where you apply the gray water and the top of the seasonally high groundwater table.

For most Phoenix homes, a simple laundry-to-landscape or shower-to-drip setup fits inside the Type 1 permit with room to spare. The savings can be real in a desert climate where outdoor watering drives the water bill. The catch is that the plumbing still has to be done right. A gray water line must never cross-connect with the drinking water system, and it needs a way to switch back to the sewer when you do not want to irrigate. For the plain-English version of whether this is legal at all, see is gray water legal in Arizona. Gray water is different from reclaimed purple-pipe water and from rainwater harvesting, which have their own rules. A property on septic also faces an on-site inspection when it sells. For a licensed setup that passes inspection, talk to a Phoenix plumber before you cut into a drain line. This page is general information, not legal advice. Confirm the current rule text with ADEQ before you build.