Do I Need a Permit to Replace a Water Heater?
Short answer
Yes, almost everywhere. Replacing a water heater is plumbing (and often gas or electrical) work, and nearly every US jurisdiction requires a permit and inspection — even for a like-for-like swap. Plumbers can usually pull the permit online the same day.
Usually exempt (no building permit)
- Very minor repairs: replacing an element, thermostat, or relief valve typically needs no permit
Permit required
- Any tank replacement — gas or electric, same size or not
- Tankless conversions (gas line sizing, venting, and electrical usually change)
- Relocations, or switching fuel type
What trips people up
- Inspectors check the details DIY swaps miss: temperature-and-pressure relief discharge piping, seismic strapping (in seismic states), combustion air, venting, drain pans, and expansion tanks on closed systems
- Unpermitted water heaters are a top item flagged in home inspections at resale
- In garages, ignition sources must be elevated 18 in. unless the unit is FVIR-rated
How to apply
Most cities sell water-heater permits over the counter or online in minutes for $25–$150. If a contractor installs it, pulling the permit is their job — make sure they actually do.
Check your jurisdiction: exemption thresholds are from the 2021 IRC (R105.2) as adopted by most states — your city or county may amend them. Find your local building department, adopted codes, and online permit portal on the BuildSpec permit pages.