Yes. Arizona allows a car wash to recycle its own wash water, and ADEQ recommends a closed-loop reclamation system. The rest of the plumbing rules still apply: an oil separator and sand control, a permit path for any water you discharge, backflow protection on the fresh supply, and marked nonpotable piping where the reclaimed water runs.
Is recycling car wash water allowed in Arizona?
It is allowed and encouraged. ADEQ's car wash guide says "In a closed-loop recycling system, wastewater is screened, cleaned, and filtered before washing the next vehicle." It also says "That's why installing an efficient closed-loop reclamation system is worth the investment." The benefits it lists: "50%-80% water savings and a reduction of the facility's sewer bills," plus fewer chemicals needed. EPA makes the same observation for the industry: commercial car washes "often recycle their water or must treat their wash water before release into the sanitary sewer system."
We looked for a Phoenix-area city ordinance that forces a new car wash to install a reclaim system and did not find one in the official text. Confirm with your city's plan reviewer, since local rules and water supplier conditions change.
Does recycled wash water need its own permit?
Not that ADEQ's guide lists for reusing your own wash water. What it does list is the discharge side. The guide says "If you discharge any wash water from your business, you may need a Type 3 General Wash Permit for your vehicle and equipment." Arizona's rule for that general permit is R18-9-D303, which "allows a facility to discharge water from washing vehicle exteriors and vehicle equipment." The rule includes conditions such as:
- Draining wash water "to a sump or similar sediment-settling structure and an oil/water separator or a comparable pretreatment technology."
- No unlined ditches or natural channels to carry wash water.
- "Only biodegradable surfactant or soaps are allowed."
- Quarterly inspection of the facility, and keeping records for 10 years.
- Extra limits for unlined impoundments or subsurface disposal, including an average flow under 3,000 gallons per day, a 100-foot setback from water supply wells, and an oil and grease target of 15 mg/l or less.
ADEQ's guide adds that a discharge that does not conform to the rule needs an individual Aquifer Protection Permit. If the wash uses reclaimed water from a treatment plant, the guide says you need a Type 2 Reclaimed Water General Permit to use Class A+ reclaimed water directly.
Two definitions keep the terms straight. Under R18-9-A701, "gray water" comes from clothes washers and bathroom tubs, showers or sinks, so vehicle wash water is a different category. "Reclaimed water" is "water that has been treated or processed by a wastewater treatment plant or an on-site wastewater treatment facility."
Do you still need a sand and oil interceptor?
Yes, and for the same reason: reuse does not change what builds up. Section 1003.4 of the 2024 IPC requires oil separators at car washing facilities, and Phoenix's sewer code lets the Director require interceptors at carwashes. Our sand and oil interceptor page covers sizing, cleaning and Valley city add-ons. ADEQ's guide also identifies sludge as the most commonly generated hazardous waste at a car wash and says to use only licensed businesses to transport and dispose of it.
What plumbing rules apply to the reclaimed water lines?
Reclaimed or recycled wash water is nonpotable, so Chapter 13 of the 2024 IPC and the marking rules in Chapter 6 matter for any tank-and-pump system.
- Scope. Section 1301.1 says "The use and application of nonpotable water shall comply with laws, rules and ordinances applicable in the jurisdiction."
- Permit and drawings. Permits are required for construction, installation, alteration and repair of nonpotable water systems.
- Purple pipe. Section 608.9 says nonpotable distribution piping "shall be purple in color" and marked "CAUTION: NONPOTABLE WATER - DO NOT DRINK," with identification repeated at intervals not exceeding 25 feet. Outlets such as hose connections carry signage reading "Nonpotable water is utilized for [application name]."
- Tanks and outlets. Above-grade storage must be shielded from direct sunlight, tanks and piping must keep insects and vermin out, and outdoor outlets on nonpotable water must be in a locked vault or operable only with a removable key.
What backflow protection does the fresh water supply need?
The connection to the city and any potable make-up line to a reclaim tank both need protection. Phoenix City Code 37-144 lists "Carwash facilities (air gap or RP)." Mesa's backflow chapter lists car wash facilities, and car wash equipment at the point of use, as needing a reduced pressure assembly. For the high-hazard case, Section 608.17.6 of the IPC calls for a reduced pressure principle assembly where a potable water connection is made to a nonpotable tank, pump or other equipment subject to high-hazard backpressure. A tank that is topped up through a hose or open pipe is an air gap problem waiting to happen; see what a reduced pressure assembly needs for drainage.
What to do before you buy a reclaim system
- 1Ask your city's wastewater group whether the reclaim blowdown and rinse water can go to the sewer and under what pretreatment.
- 2Check whether your discharge needs the ADEQ general permit.
- 3Ask your plumber to draw the nonpotable lines, tank, make-up water and backflow assemblies together, so the plan reviewer sees one system.
HQ is licensed and insured and gives free estimates, with upfront pricing, for the plumbing side: supply lines, backflow assemblies and drain connections. Where the wash water goes after your property is covered on where car wash wastewater can drain in Arizona.