Water heaters are one of the most common sources of household water damage because they're always under pressure and often tucked in garages, closets, or attics where leaks go unnoticed. A slow drip can quietly rot a closet floor; a failed tank can release its full capacity at once.
What water heater leak involves
Handling a water heater leak has two parts: shutting the unit down safely and repairing or replacing it (usually a plumber), and cleaning up and drying the area around it (the water damage side).
Common causes
- Tank corrosion
- Tanks corrode from the inside over time. Rust-colored water or rust at the base can be warning signs.
- Temperature and pressure relief valve
- The T&P valve may discharge if pressure or temperature gets too high, or leak if it's failing.
- Drain valve
- The valve near the bottom can drip if it's loose or worn.
- Supply connections
- Inlet and outlet fittings on top of the tank can loosen or corrode.
- Failed drain pan or line
- Pans under attic or closet units can overflow if the drain line is blocked.
What to do right now
- Turn off the cold water supply valve on the pipe feeding the heater. If you can't find it or it won't turn, shut off the main.
- For an electric unit, switch off its breaker. For a gas unit, turn the gas control to 'off' or 'pilot' per the label on the unit.
- If you smell gas, leave the house and call 911 or the gas utility from outside.
- Keep clear of hot water; tank water can scald.
- Remove standing water and move stored items away from the heater.
- Photograph the heater's label (for model and age) and the damage.
What to avoid
- Don't touch the T&P valve discharge; the water can be scalding.
- Don't try to drain a heater that's actively leaking from the tank body unless you know how; it may be simpler to let a plumber handle it.
- Don't leave an electric heater powered on with the water supply off; heating elements can be damaged.
- Don't ignore a small leak at the base. Water often travels under walls and flooring nearby.
Where the water goes
Water heaters in garages often leak onto concrete, which is relatively forgiving, but water can still run under the wall into adjacent rooms. Heaters in interior closets or attics are riskier: water can soak the closet floor, the subfloor, nearby drywall, and the ceiling below. Check neighboring rooms for damp baseboards and stains.
Repair or replace?
That's a question for a licensed plumber. A leaking valve or fitting can often be repaired. A leak from the tank itself generally means the unit needs replacement. Knowing the unit's age helps; it's usually encoded in the serial number on the label.
Damage it can cause
- Rotted closet or utility room subfloor
- Wet drywall and baseboards in adjacent rooms
- Ceiling damage below attic-installed units
- Damaged belongings stored near the heater
When professional help may be appropriate
- The tank has ruptured or water spread beyond the immediate area
- The heater is in an attic or interior closet and water reached the floor or ceiling
- You can't safely shut off gas or power
- Water has been leaking for an unknown length of time
If any of these apply, it may be time to talk to a provider.
Request HelpQuestions to ask a provider
- Will you check the subfloor and adjacent walls for moisture?
- Can you coordinate with a plumber for heater replacement?
- Which materials near the heater need replacement versus drying?
Providers you reach through this site are independent. Verify licensing, insurance, and pricing directly with them before authorizing work.
Water Heater Leak: common questions
What should I do if my water heater is leaking?
Turn off the cold water supply to the heater, shut off power (electric) or set the gas control to off or pilot, keep clear of hot water, and call a plumber. Then remove water and check surrounding areas for spread.
Is a leaking water heater an emergency?
A small drip at a fitting isn't usually an emergency but should be addressed soon. Water pouring from the tank, any smell of gas, or water reaching electrical components is urgent.