Do I Need a Permit to Replace a Water Heater in Montana?
Quick Answer
Yes — even for a like-for-like replacement.
Why a Simple Swap Needs a Permit
Most jurisdictions require a permit for all water heater replacements, even when you're installing the same type and size. The permit ensures proper venting, gas connections, temperature/pressure relief valve discharge, and seismic strapping. Improper water heater installations are a leading cause of residential CO poisoning and water damage.
What Inspectors Check
The inspector will verify: gas line connections and drip leg (sediment trap), proper venting (metal B-vent for standard, PVC for high-efficiency), T&P relief valve discharging to within 6 inches of the floor or exterior, seismic strapping (two straps — upper and lower third), and adequate combustion air supply.
Tankless Conversion
Converting from a tank to tankless water heater often requires additional work: a larger gas line (tankless units draw more BTUs), PVC venting (most tankless units are high-efficiency), and potentially an electrical outlet for the unit. This may trigger both plumbing and gas permits.
DIY vs. Hiring a Plumber
Many jurisdictions allow homeowners to replace their own water heater in their primary residence — confirm with your city. You still must pull the permit and pass inspection. Most homeowners hire a licensed plumber because the permit and inspection process is simpler when the contractor handles it.
Bottom Line
Yes, you need a $40-$60 permit. It's a quick same-day approval and one final inspection. Don't skip it — it protects you and your home.
Permit fees by city in Montana
Verified from each city’s published fee schedule. Where a city has no separate fee listed for this project, open the city page for the current requirements and amount.
| City | Permit fee | Source |
|---|---|---|
| Anaconda-Deer Lodge | $10 eachVerified | Plumbing Permit → |
| Billings | $20.00Verified | Plumbing Permit → |
| Bozeman | Determined based on contractor valuation of the project, subject to Building Division approval of the valuation, applied against Table CVerified | Plumbing Only Permit → |
| Butte-Silver Bow | $75.00 per hour, one-hour minimumVerified | Plumbing Permit → |
| Great Falls | $34.39Verified | Plumbing Permit → |
| Havre | $60Verified | Residential Plumbing Permit (including Water Heater) → |
| Helena | $21.00Verified | Plumbing Permit → |
| Kalispell | $20.00 base fee plus $8.00 per plumbing fixture and/or gas outletVerified | Plumbing Permit → |
| Missoula | $43.00Verified | Residential Plumbing Permit → |
| Unincorporated Yellowstone County | $25Verified | Water Heater Permit → |