Plumbing code sets the minimum safety standard for the pipes and devices in your walls, and in Phoenix it also makes you the one responsible for keeping them in safe, working order. It decides when you need a permit, who may do the work, and whether a repair or remodel must meet today's rules.
1. It exists to keep you safe
The International Plumbing Code, which Phoenix adopted with its own amendments effective August 1, 2025 (Ordinance G-7397), states its purpose in Section 101.3: "to establish minimum requirements to provide a reasonable level of safety, health, property protection and general welfare by regulating and controlling the design, construction, installation, quality of materials, location, operation and maintenance or use of plumbing equipment and systems." The word to notice is minimum. Code sets the floor, not the best practice. Rules like the relief valve on your water heater and the vacuum breaker on your hose bib come from here (see the plumbing safety devices a home needs).
2. You are responsible for maintenance
Section 102.3 says plumbing systems "both existing and new, and parts thereof, shall be maintained in proper operating condition in accordance with the original design in a safe and sanitary condition." Then it names who: "The owner or the owner's authorized agent shall be responsible for maintenance of plumbing systems." The code official also has "the authority to require any plumbing system to be reinspected" to check. Devices the code requires "shall be maintained in compliance with the edition of the code under which they were installed," so a water heater valve that was legal when installed has to stay working, not just stay in place.
3. Old plumbing isn't automatically illegal, but new work must be up to date
Section 102.2 lets plumbing "lawfully in existence at the time of the adoption of this code" keep being used and maintained if the work follows the original design and "hazard to life, health or property is not created." The catch is in 102.4: additions, alterations, renovations and repairs "shall conform to that required for a new plumbing system without requiring the existing plumbing system to comply with all of the requirements of this code." Minor repairs may match the existing arrangement if they are not hazardous and are approved. In practice, your 1980s house isn't forced to be rebuilt, but the part you touch has to meet today's code, and the change must not make the rest "unsafe, unsanitary or overloaded."
4. It decides permits, inspections and who can do the work
Phoenix's administrative provisions spell out what doesn't need a permit, such as "The clearing of stoppages or the repairing of leaks in pipes, valves or fixtures and the removal and reinstallation of water closets, provided such repairs do not involve or require the replacement or rearrangement of valves, pipes or fixtures," and the like-for-like replacement of a water heater in a one- or two-family home when a licensed contractor does the work. Remove and replace a defective concealed drain or supply pipe and "such work shall be considered as new work and a permit shall be obtained and inspection made." Our page on what plumbing work needs a permit in Phoenix covers the list.
On who does permitted work, Section 119.1 requires a licensed journeyman or apprentice, with exceptions, including an Arizona-licensed contractor, and "The owner/occupant of a single-family residence when performing work covered by this section on their residence or accessory buildings or structures."
Skipping the permit has a published price. The City's fee schedule lists an investigation fee for work done without a permit of "$250 or the permit fee, whichever is greater, but not to exceed $2,500 for every day or portion of a day from the time unpermitted work began until a permit is obtained." That is the city's schedule, so confirm the current amount with Planning and Development before you rely on it.
Why this shows up when you sell
Permits and final inspections leave a record that the work was checked. Pipes closed up inside a wall can't be looked at later, which is why concealed plumbing before the required inspection is worth a read before a remodel. If you're buying, what a home buyer should know about plumbing before closing covers the other side of the table.
What this means for you
- Treat the code as your minimum maintenance standard, not the contractor's problem alone.
- Before any change beyond a like-for-like repair, check whether it needs a permit.
- Hire a licensed contractor for permitted work you don't want to do yourself. HQ is licensed and insured, with free estimates and upfront pricing, for residential plumbing.
This page is general information. The Phoenix Planning and Development Department decides how the code applies to a specific job.