Water Dripping Inside the Water Heater
On this page (6 sections)
The Short Answer: Water inside a tank heater has three usual sources. On gas heaters, flue condensation drips while a tank of cold water heats, then stops. A leaking fitting on top can run down inside the jacket. Or the tank has rusted through. Condensation clears on its own and a fitting can be replaced, but a leaking tank means a new heater.
Where the water shows up
- Gas heater, burner compartment: you may hear sizzling or see drips on the burner through the sight glass.
- Electric heater, behind an element cover: you see rust stains or wet insulation, or a status light reports a fault.
- Between the jacket and the tank: water seeps out from the bottom edge of the jacket.
Condensation or a leak?
Burning gas produces water vapor. When the tank is full of cold water, for example after long showers or right after installation, that vapor condenses on the cold flue tube and drips onto the burner. It can sizzle and may even put out the pilot. A. O. Smith’s condensation bulletin (opens in a new tab) describes this: a typical heater produces about half a gallon of water vapor per hour of burner operation, and condensation usually stops once the tank water warms past roughly 115°F. The same bulletin suggests a simple check. Set the gas control to PILOT for about eight hours and see whether water still collects; if it does, the cause is a leak, not condensation.
| Clue | Points to condensation | Points to a leak |
|---|---|---|
| Timing | Mostly at first startup or after heavy hot-water use | Happens with the burner off or the tank already hot |
| Trend | Lessens as the tank heats | Stays the same or gets worse |
| Water temperature | Cool | Warm, or the same as the tank |
| Other signs | None | Rust streaks, mineral crust, wet insulation at the base |
| Electric heater | Does not apply (no combustion) | Any water inside the element compartment is a leak |
Common sources of a leak
- Fittings on top: a corroded nipple, connector, anode port, or relief valve can drip down the outside of the tank under the jacket. See water coming from the top of the water heater.
- Element gasket (electric): water at one element cover while the rest of the tank is dry often comes from the gasket.
- Relief valve discharge: a relief valve that has been discharging can wet the side of the heater.
- Tank failure: water that appears at the bottom of the jacket or in the burner area, with all fittings dry and no cold-start timing, usually means the tank has rusted through. See water leaking from the bottom of the tank.
What you can do now
- Turn off the energy source: the gas control to OFF, or the breaker for an electric heater.
- If water is actively leaking, close the cold-water inlet valve if it is clearly labeled and you can reach it.
- Dry the outside of the heater and the floor. Over the next hour, check which fitting, cover, or seam gets wet first.
- On a gas heater, note whether the dripping happens only while the burner heats a tank of cold water. If so, condensation is likely.
- Write down what you saw and when, and pass it on to the technician; prepare for service covers what else to note.
What the technician will check
A technician will inspect the burner, flue, and combustion chamber for rust, scale, and soot, and check the fittings and relief valve on top. On electric models, they switch the power off and check the element gaskets and the compartments. They may run the heater from cold and watch to confirm condensation. If the tank itself is leaking, there is no repair. Sealants and patches are not safe on a pressurized tank.
Frequently Asked Questions
Q: My new gas water heater drips on the burner. Is it defective? A: Not necessarily. A new tank starts full of cold water, so condensation on the flue is common for the first heat-up. If the dripping stops once the tank is hot, it was condensation. If it continues with the tank hot, have the installer check it.
Q: Can I use the water heater while it drips inside? A: Not if water is reaching the burner or an electrical compartment because of a leak. Turn the heater off and close the cold inlet until it has been checked. Brief condensation during a cold start is different and normally clears up by itself.
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.
- A. O. Smith technical bulletin 15: condensation (opens in a new tab)Why combustion condensate can resemble a tank leak; not a diagnosis of another manufacturer’s model.
- A. O. Smith technical bulletin 51: puddles around a heater (opens in a new tab)Common water-leak sources and the distinction between fittings and a failed tank.
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