Gas Water Heater Got Wet and the Pilot Won't Light
On this page (6 sections)
The Short Answer: If floodwater reached the gas control or burner, don’t relight the heater. Gas water heater labels say not to use the heater if any part has been under water, and to have a qualified technician replace any submerged control parts. Water can corrode the valve and sensors without visible damage. Even a burner that was only splashed needs checking and drying first.
Why a wet heater won’t light, and why that’s a good thing
Water can soak the pilot assembly, the igniter, the thermocouple or thermopile, and on most newer tanks the flame-arrestor screen at the bottom that lets in combustion air. Any of these can stop the pilot lighting or keep it from staying lit. More importantly, a gas control that has been submerged can fail in ways that aren’t obvious, which is why the instructions call for replacing it instead of drying it out.
How it got wet decides what happens next
| What happened | What it usually means | Next step |
|---|---|---|
| Floodwater rose to or above the gas control or burner door | Control and burner parts submerged | Leave it off; technician replaces affected parts or the heater |
| Burst pipe or roof leak sprayed the outside of the heater | Burner area may be wet | Leave it off; technician inspects and dries it |
| Water dripping onto the burner from above | Leaking fitting, relief valve, vent condensation, or the tank | Find the source; see gas water heater dripping on burner |
| Wet after heavy rain, no flooding | Water coming down the vent | See gas water heater not working after rain |
| Rust and scale at the burner, water returns with all fittings dry | Tank leaking into the combustion chamber | Replacement |
What you can do safely
- Turn the gas control to OFF if you can reach it without standing in water, and close the gas supply valve to the heater.
- Stop the water. If the heater itself is leaking, close the cold-water valve above it. Never wade through standing water near gas or electrical equipment.
- Don’t press the igniter repeatedly or hold the knob in to “dry it out.”
- Photograph the water line on the heater and the room before cleanup. Your insurer and the technician will both want to know how high it reached.
- Arrange inspection before any relight. After area flooding, gas utilities and local officials often advise having every gas appliance checked.
What the technician will check
A technician looks for the high-water mark, inspects the gas control, pilot assembly, igniter, thermocouple or thermopile, and flame arrestor for water, silt, and corrosion, and checks the vent and combustion chamber. Submerged controls are replaced. If the burner area was only dampened, they may dry and clean it, test the safety devices, and relight once they confirm the source of the water has been fixed.
Repair or replace
Replacing a gas control, pilot assembly, and thermocouple or thermopile is a significant repair but still less than a new heater on a newer tank. Heaters that sat in floodwater are often replaced, because the insulation, jacket, and burner area are also contaminated. A tank that leaks into its own burner is always a replacement.
Frequently Asked Questions
Q: The flood water never reached the gas valve. Is it safe to relight? A: Not until someone has checked the burner area and flame-arrestor screen, which sit lower than the gas control. If water reached the bottom of the heater, it may have reached the burner.
Q: Can I dry the pilot with a hair dryer and relight it? A: No. Drying the outside doesn’t show whether water got into the control or sensors, and a damp flame-arrestor screen can cause poor combustion. Leave it to a technician.
Manuals and supporting references
These links distinguish general safety information from model-specific documentation. A manual directory helps you locate your unit’s instructions; it does not establish that every model uses the same parts, codes, or test values.
- PG&E: recognizing and responding to a gas leak (opens in a new tab)Emergency actions for suspected fuel-gas leaks.
- CPSC: carbon monoxide fact sheet (opens in a new tab)Carbon monoxide hazards and emergency response.
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