Tank Water Heater Drain Pan
Install a drain pan under any tank water heater located in or above conditioned living space.
Spec
Applies uniformly from Certified upward.
Scope
Tank-style water heaters located in or above conditioned living space (e.g. utility closets on upper floors, attic installations). Garage and basement installations are excluded if a tank failure would not damage living space.
Requirements
- 01.
Install a drain pan rated to fully contain a worst-case tank-failure leak under the water heater.
- 02.
The pan must have a plumbed drain line routed to a safe discharge point (floor drain, exterior wall, or condensate line) per IPC §504.7.
- 03.
Pan material: galvanized steel (≥ 24 ga) or aluminum, OR plastic rated for sustained 140°F exposure.
Documentation
Evidence the inspector / Institute will need.
- 01.
Photo of the installed pan showing the tank seated in it and the drain line connection.
- 02.
Photo of where the drain line discharges (must be visible / observable per code).
Guidance
Tankless heaters
Tankless water heaters are exempt from this requirement — their failure mode is leak-free (they shut off on internal fault). However, GHI recommends still installing a small drip pan + sensor under tankless units mounted in conditioned space, since fittings on cold-water inlet and TPR valves can still fail.
Pan sizing
The pan must extend at least 2 inches beyond the tank diameter on all sides per most jurisdictions. Standard pans come in 22", 24", 26", and 28" diameters — match to your tank.