Not always. Under Section 105.2 of the 2024 Phoenix Building Construction Code, a licensed contractor's in-kind water heater swap in a house or duplex needs no permit. A homeowner swap, a fourplex or business, or a change of fuel, type or location needs one. The work must still meet code.
When is a water heater swap exempt from a permit?
Section 105.2 of the 2024 Phoenix Building Construction Code (Ordinance G-7397, in force since August 1, 2025) lists the plumbing work that needs no permit. Item 5 reads: "Replacement, in kind, of an existing water heater in one-and two-family dwellings when the work is performed by a licensed contractor."
Three phrases decide it:
- In kind. Section 105.2 doesn't define it. The common reading is the same fuel, the same type, about the same size and the same location, with no new gas, water or vent routing. That is a reading, not the code's wording. A 50-gallon gas tank replaced by another 50-gallon gas tank fits it cleanly.
- One- and two-family dwellings. A house or a duplex. A fourplex, apartment building or business isn't covered by item 5. For how federal rules tell a commercial heater from a residential one, see commercial vs residential water heaters.
- Licensed contractor. An Arizona-licensed contractor. You can check any contractor on the Arizona Registrar of Contractors license search.
Quick check: which jobs need a permit?
| Job | Permit? | Why |
|---|---|---|
| Licensed contractor swaps a gas tank for the same kind of gas tank in a house | No | Item 5 |
| The same swap in a duplex | No | Item 5 covers two-family homes |
| The same swap in a fourplex or apartment building | Yes | Not a one- or two-family dwelling |
| A homeowner does the same swap | Yes | Item 5 requires a licensed contractor |
| Tank to tankless | Yes, by the usual reading | Usually changes the venting and gas sizing, and item 5 doesn't mention it |
| Gas to electric, or electric to gas | Yes | Fuel changes fall outside "in kind" |
| Heater moves from the garage to a closet | Yes | Location changes fall outside "in kind" |
Valley scenarios
- Saturday failure in Ahwatukee. A licensed contractor replaces a failed 40-gallon electric tank with another 40-gallon electric tank in the same closet. No permit. The install still has to meet code.
- Homeowner in Maryvale. A homeowner buys a matching gas tank and swaps it. Same heater, but the person doing the work isn't a licensed contractor, so item 5 doesn't apply. That is the edge case where the answer flips.
- Tankless upgrade in Arcadia. A gas tank comes out and a wall-hung tankless goes in on new venting and a bigger gas line. This is not an in-kind swap by the usual reading, so plan on a permit.
Myths about water heater permits
- "Every water heater swap needs a permit in Phoenix." Several contractor pages say so. Item 5 says otherwise for a licensed contractor's in-kind swap in a house or duplex.
- "No permit means no rules." Section 105.2 opens with the opposite: exemptions "shall not be deemed to grant authorization for any work to be done in any manner in violation of the provisions of this code."
- "The old City guide still applies." Older City documents were written for earlier code editions. The 2024 code has applied since August 1, 2025.
What if the water heater fails and you need hot water now?
Phoenix's code allows replacement equipment to run in an occupied building as long as a request for inspection is filed with the building official within 72 hours after the replacement work is completed, and before any part of the equipment is concealed (Section 110.3.10.1). So a Saturday failure doesn't have to mean cold showers until Monday. The City takes residential inspection requests through the SHAPE PHX portal or by phone at 602-495-0800.
Does an exempt swap still have to meet code?
Yes. The paperwork is waived. The rules aren't.
The big one is the temperature and pressure (T&P) relief valve. A water heater is a sealed tank of hot water under pressure, and the valve opens if temperature or pressure climbs too high. Under the 2024 Phoenix Residential Code (Section P2804.6.1), the discharge pipe must "discharge through an air gap located in the same room as the water heater." Capping or plugging that pipe is a rupture and scald risk. The plumbing-code version of the rule is in UPC 608, relief valve discharge, and the install rules for the heater itself are in UPC 507, water heater installation.
Two more things an inspector or a buyer's inspector will look at:
- Venting and the gas hookup on gas units. A gas water heater makes carbon monoxide, and the flue has to carry it out of the home; UPC 510 covers water heater venting. The gas connection matters too, including the sediment trap, or drip leg the manufacturer calls for. A working carbon monoxide alarm outside the bedrooms is the backup if venting ever fails.
- Thermal expansion. On a closed system, heated water has nowhere to go, and an expansion tank absorbs the pressure spike. See do I need an expansion tank.
How do other Valley cities treat a water heater swap?
The same like-for-like test applies to other work in the house. Adding a fixture, such as a sink in the laundry room, is new plumbing, and our laundry room sink page shows where the drain can go and why it needs a permit.
Whether the owner may do the work at all, and what the inspector checks, is covered in can I install a water heater myself in Arizona.
Here is what to do
Phoenix ties its exemption to who does the work. Three other Valley cities word it differently (checked 2026-09-29):
| City | Rule | Source |
|---|---|---|
| Scottsdale | Permit required: "A permit is required for Water Heater replacement. A permit may be obtained by the homeowner or a licensed contractor." | City handout (undated) |
| Mesa | No permit for "residential replacements of gas and electric water heaters of equal or lesser rating using a 'like for like' model." Storage gas to tankless needs one, and the gas utility must be notified before the appliance goes into service. | City FAQ |
| Chandler | Item 10 of the exempt list: "Like for like replacement of residential water heaters and water softeners..." | Homeowner Permit Manual, Rev. 4/09/26 |
Mesa and Chandler don't mention a contractor in the exemption text, and Scottsdale requires a permit even for an identical swap. Moving between cities changes the answer, so check the city where the heater sits.
What to do next
- 1Match your job to the table above. If it isn't a clean fit for item 5, plan on a permit.
- 2Ask the contractor who files. For a job that needs a permit, permitting and inspection requests for residential work go through the City's SHAPE PHX portal (shapephx.phoenix.gov). The Development Center at 200 W Washington Street, 2nd floor, is open Monday to Friday, 8 a.m. to 5 p.m., at 602-262-3111.
- 3Verify the license on the ROC license search before work starts.
- 4File the inspection request through SHAPE PHX or at 602-495-0800 within 72 hours of a same-day replacement, and before anything is concealed.
- 5Keep the invoice with the model number and the contractor's license number.
HQ is licensed and insured, and gives free estimates and upfront pricing before work starts.
If your house is in Mesa instead, the rule is different for a tank to tankless swap. See do I need a permit to go tankless in Mesa.
Full text and source
The rule is Section 105.2, Plumbing, item 5, and Section 110.3.10.1, item 4, in the City of Phoenix Amendment to the 2024 International Building Code, Chapter 1, part of the 2024 Phoenix Building Construction Code (Ordinance G-7397, approved June 18, 2025, effective August 1, 2025). Which codes Phoenix adopted, and the UPC or IPC choice, is explained in which building and plumbing codes Phoenix enforces. Read the rule at the City's chapter 1 amendment PDF. This page explains it, and the official text governs.
In a leased commercial space, the lease decides who pays for the replacement; see who replaces the water heater in a leased commercial space.
Outside Phoenix the rules change; see which Valley cities require a water heater permit.
When replacement is chosen, arrange safe disposal of the old heater, including city recycling eligibility and refrigerant handling for heat-pump models.
Our guide to plumbers and electricians installing water heaters explains the separate water, gas, venting and electrical scopes to confirm before a replacement.
Where the relief valve discharge pipe goes and when a pan is required are covered in commercial water heater relief valve discharge and pan rules.