What plumbing code does Phoenix use?

Phoenix uses two plumbing model codes. The city's construction code history (TRT 00550) lists what took effect on August 1, 2025 under Ordinance G-7397: the 2024 International Plumbing Code (IPC) with Appendices C and E, and the 2024 Uniform Plumbing Code (UPC) with Appendices A, B, C, I and M, next to the 2024 building, residential, mechanical and fuel gas codes. All of them apply with Phoenix amendments. The previous set was the 2018 codes (Ordinance G-6463, effective July 6, 2018).

Which one governs a given job? The administrative provisions answer it. Section 101.4.3 says: "The provisions of the Uniform Plumbing Code or International Plumbing Code, as amended, shall apply to the installation, alteration, repair and replacement of plumbing systems." In practice the plumbing designer picks the UPC or the IPC, and a house can follow the 2024 International Residential Code. The UPC is published by IAPMO and the IPC by the ICC. They cover the same ground, such as drains, vents, traps and fixtures, but they word some rules and set some numbers differently. That is why the code family, the edition and the amendments all matter.

Phoenix does not adopt either code word for word. The city attaches local amendments that add, remove or change sections, so the true rule for a job is the model code as amended by Phoenix. Local amendments exist because national codes are written for the whole country, not one desert city, and the amendment list is part of the legal rule.

Arizona has no single statewide plumbing code. The state does not pick one edition and force every town to use it. Instead, each city and county adopts and amends its own building and plumbing codes. This is the single most important fact for anyone working across the metro area.

The practical effect is real. A job in Phoenix follows the 2024 UPC or 2024 IPC with Phoenix amendments. A job in another Arizona town might follow a different edition, an older edition, or only the IPC. Two houses 20 miles apart can sit under different rule books. A contractor who works in several cities has to confirm the code for each one, not assume Phoenix rules apply everywhere.

This also means the adopted edition changes over time. Cities update on a cycle, often every three years, to match new model-code releases. The edition in force this year may not be the one in force a few years from now. Always confirm the current adopted edition before you design or price a job.

The official source is the City of Phoenix Planning and Development Department, often shortened to PDD. Its codes-and-ordinances pages list every code the city has adopted, the edition, the effective date, and the local amendments. This is the page to check, not a third-party summary or a plumber's blog.

When you look it up, confirm three things:

• The code family: the UPC or the IPC, since Phoenix adopted both.
• The edition year, currently 2024 for both.
• The Phoenix amendments, which are published as a separate list or built into the adopting ordinance.

For the national text behind the rule, IAPMO publishes the UPC and the ICC publishes the IPC. Free reading mirrors such as UpCodes show the model-code sections, which is useful for understanding a rule. Just remember the city amendments control wherever they differ from the model text. As the city frames it on its Planning and Development pages, Phoenix has adopted the Phoenix Building Construction Code as the set of codes that govern construction within the city.

The adopted code is the rule book for permits and inspections. When you apply for a plumbing permit, the plan reviewer checks your work against the adopted 2024 code and Phoenix amendments. When the inspector visits, that same code is the standard your installation has to meet. Fail it and you do not pass, no matter how good the work looks. The code also puts duties on owners after the work is done; why plumbing code matters for homeowners covers the maintenance rule in Section 102.3.

The code also sets the everyday numbers that decide whether a fixture is legal. A few examples, with the UPC section where the number comes from:

• Drain pipe slope. Horizontal drains generally need a minimum 1/4 inch per foot of fall (a 2 percent grade) for pipes up to 3 inches. See drain pipe slope code for the full table.
• Shower size. A shower needs a minimum 1,024 square inches of interior floor area and must fit a 30-inch circle, held to a point 70 inches above the drain. See minimum shower size code.
• Venting and fixture clearances. The code sets how far a trap can sit from its vent and how much clear space a toilet needs on each side, so sewer gas stays out and fixtures fit.

These are not arbitrary. Slope keeps solids moving so a drain does not clog. Venting protects the trap seal, the small pool of water in every trap that blocks sewer gas from entering the room. Clearances make a bathroom usable and serviceable. Each rule ties back to the adopted code, which is why the edition you build under is more than a formality.

The code matters for resale and insurance too. Work done without a permit, or work that does not meet the adopted code, can surface during a home sale or an insurance claim. An inspection that flags unpermitted plumbing can stall a closing or force a costly fix later. Building to the current adopted code and pulling the right permit protects the value of the work, not just its function.

The code also decides what work needs a permit in the first place. See what plumbing work needs a permit in Phoenix and, for ground-up jobs, new construction plumbing permit in Phoenix.

Yes, and this is the part people miss. The city adopts a new model-code edition on a regular cycle, and the effective date sets the line. Work permitted before the change may fall under the older edition, while new permits follow the current one. The 2024 codes took effect August 1, 2025, but a future update will replace them.

Editions can shift specific numbers, add new product standards, or change how a section reads. A rule that was true under an earlier UPC may be different in the 2024 edition or the one after it. For this reason, verify the current adopted edition and amendments on the City of Phoenix Planning and Development pages before relying on any figure, including the ones on this page. When the rules govern a permit or an inspection, the official city source is the only one that settles it.

Two places the adopted code shows up in commercial work: commercial fixture counts and drinking fountain and bottle filler requirements.

To see how the IPC and UPC choice changes a real question, read are air admittance valves allowed in Arizona: the IPC permits them and the UPC has no section for them.