Code Library
Water Heaters: Rules in Phoenix-Area Cities
Water heater permits, installation rules, venting, relief valves, drain pans and expansion control. City by city, then the Arizona law and model code behind it.
Uniform Plumbing Code
All UPC sections- Model Code · Updated Jul 2026UPC 506: Combustion Air for Gas Water HeatersUPC Section 506 sets how much fresh air a gas water heater's burner gets and where that air comes from. A small closet is a confined space and needs sized free-air openings, high and low, to outside or an adjacent room so the burner does not starve, soot, or backdraft.
- Model Code · Updated Jul 2026UPC 510: Venting Gas Water Heaters (Category I Flues)UPC Section 510 sets how a natural-draft gas water heater's flue and vent are sized so the exhaust leaves the building instead of spilling back inside. Nearby sections control the draft hood, the vent connector, and how the heater shares a vent with another appliance.
- Model Code · Updated Jul 2026UPC Section 507: Water Heater Installation RequirementsUPC Section 507 sets the general installation rules for a water heater: it must be accessible for service, anchored against movement, and placed where a code official allows it. These rules sit alongside the separate requirements for relief-valve discharge, clearances, and drain pans that also govern a safe install.
- Model Code · Updated Jul 2026UPC Section 608: Water Heater Relief Valve and Discharge Pipe RulesUPC Section 608 requires every water heater to have a temperature and pressure relief valve and a discharge pipe that carries released hot water to a safe place. The pipe must run downhill, stay full size, carry no valve or cap, and end near the floor so nobody is scalded.
- Model Code · Updated Jul 2026UPC Water Heater Drain Pan: When One Is Required and How It DrainsPlumbing code requires a drain pan under a water heater where a leak or tank failure could damage the building, such as an attic, an upper floor, or over finished space. The pan catches leaking water and a pan drain carries it to a safe spot, so a slow leak does not flood the area below.
Need The Work Done To Code?
Call a licensed plumber who pulls the permit in your city and passes inspection the first time.