The straight answer
Yes. In Walworth, Waukesha, and Racine Counties, a water-heater changeout almost always requires a permit:
- Gas tank water heater → gas tank water heater: plumbing permit (sometimes mechanical) required.
- Electric tank water heater: plumbing + electrical permit typically required.
- Tankless conversion (tank → tankless): plumbing + mechanical (for venting + gas line) + sometimes electrical permits required. Always the most permit-heavy of the four scenarios.
- Tankless → tankless (like-for-like replacement): plumbing permit, possibly mechanical depending on venting changes.
Why a permit is required for what looks like a simple swap
A water heater touches three life-safety systems:
- Combustion + venting. A gas water heater needs proper combustion air, a properly sloped vent connector, the right vent diameter, and termination clearances. Wrong venting causes carbon monoxide spills into the home. Inspectors check this on every install.
- Gas pressure + leak testing. Gas line connections must pass a pressure test (typically [verify: 25 psi for [verify: 15 minutes] with no drop, per Wisconsin Fuel Gas Code]).
- T&P relief discharge. The temperature & pressure relief valve must discharge safely — full pipe diameter, terminated to an appropriate location, never threaded at the end.
Beyond safety, a permitted install creates the paper trail that:
- Preserves the manufacturer warranty.
- Satisfies insurance requirements.
- Doesn't blow up your closing if you sell.
What we actually pull
For a typical East Troy gas tank-to-tank replacement we pull a single plumbing permit. Total fee is usually in the [verify: $50–$120 range depending on AHJ]. The inspection happens once installation is complete — the inspector verifies vent termination, gas connections, T&P discharge, and the seismic strap (where required).
For a tankless conversion the permit packet typically grows to:
- Plumbing permit for the water connections + T&P.
- Mechanical permit for the venting (often direct-vent through the sidewall).
- Possibly a gas-line upsizing permit if we have to bring the meter up to handle the larger BTU load.
- Possibly an electrical permit if a dedicated circuit is required.
What about "the box store said no permit"?
Big-box water-heater install contractors sometimes skip the permit on routine swaps. We don't. Aside from the legal and safety issues, when something goes wrong (CO incident, gas leak, water damage from a bad T&P discharge), the unpermitted install is the first thing the insurer will point to.
Action
- Request a water-heater quote — the permit and inspection are always included.
- Read the tankless vs tank explainer if you haven't decided yet.
