Does a water heater need a temperature and pressure relief valve?
Yes — every water heater must have a temperature-and-pressure relief valve (or separate temperature and pressure valves) set to open by 210°F and 150 psi (IRC P2804).
The IRC requires every water heater to be protected by a temperature-and-pressure (T&P) relief valve, or by separate temperature and pressure relief valves. The temperature element must open at no more than 210°F (99°C), and the pressure relief at no more than 150 psi (IRC P2804.3 and P2804.4).
The valve's discharge pipe must run full-size to a safe spot, terminate near the floor or outdoors, and cannot have a shutoff valve, threaded end, or trap that could block flow (IRC P2804.6.1).
These devices prevent the tank from over-pressurizing. The discharge line must never be capped or plugged.
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Need this scoped to your jurisdiction?
Adopted edition and local amendments vary by city and county. Ask Donnie checks your jurisdiction and cites the exact adopted section.
Ask Donnie →General information based on the International Residential Code (a model code). This is AI assistance to verify — not legal advice. Confirm the adopted edition and any local amendments with your local building department (AHJ) and a licensed professional before you build.