Guide · Appliances
Water heater leaking: what to do and when it needs replacing
Water heaters fail in two ways: a slow drip that rots the floor, or a tank that splits and dumps 40 to 80 gallons. Either way, the first steps are the same.
Shut it down
- Turn off the energy. Gas: turn the control knob to off or pilot, and close the gas valve on the supply line. Electric: switch off the water heater's breaker.
- Close the cold water supply valve on the pipe going into the top of the tank. If it won't turn, shut off the main.
- Let the water cool for a few hours if you need to drain it. Tank water can be hot enough to scald.
- Drain the tank if it's leaking from the bottom. Attach a garden hose to the drain valve near the bottom, run it to a floor drain or outside, open a hot faucet upstairs to let air in, and open the drain valve.
Where is it leaking from?
| Location | Likely cause | Usually means |
|---|---|---|
| Pipe connections on top | Loose fitting or corroded connector | Repairable |
| Temperature and pressure relief valve or its discharge pipe | Valve doing its job because pressure or temperature is too high, or a failing valve | Needs a plumber to diagnose. Never cap or plug this valve. |
| Drain valve at the bottom | Valve not fully closed or worn out | Repairable |
| Bottom of the tank or under the jacket | Tank corroded through | Replace the water heater |
| Puddle with no visible drip | Condensation on a cold tank, or a leak from a nearby pipe or furnace | Dry everything, then watch where the water reappears |
Signs the tank is near the end
- Rusty or discolored hot water, but not cold.
- Rumbling or popping from sediment buildup.
- Moisture or rust around the base.
- Age. Tank water heaters commonly last around 8 to 12 years. The manufacture date is usually coded into the serial number on the label.
Dry the area quickly
Water heaters usually sit in basements, garages, utility closets or, in some homes, an upstairs closet over a finished ceiling. Mop up standing water, pull wet boxes and rugs away, and check the drywall and baseboards around the closet with your hand. If water ran under walls or into a finished ceiling, it needs professional drying: the EPA advises drying water-damaged materials within 24 to 48 hours to prevent mold.
Limit the damage next time
- Set the tank in a drain pan piped to a floor drain, especially in a finished basement or upstairs closet.
- Add a water leak sensor or an automatic shutoff valve.
- Flush sediment once a year, following the manufacturer's instructions.
- Ask a plumber to check the anode rod and whether you need a thermal expansion tank.
Insurance
Water damage from a sudden tank failure is usually covered. The water heater itself, and damage from a slow leak that went on for weeks, usually aren't. See what homeowners insurance covers.