No hot water? Start here
A water heater that stops heating often has a simple cause. On an electric heater, check the breaker and the reset button. On a gas heater, check whether the pilot light has gone out. On either kind, make sure the thermostat hasn't been turned down. Those checks cost nothing and take a few minutes. While you're there, check the date on the label. Tank water heaters often last around 10 years, give or take, and an older one that starts acting up may be near the end.
How your water heater works
Most homes have a tank water heater that keeps 40 or 50 gallons hot around the clock. Gas models heat with a burner lit by a pilot light or electronic igniter. Electric models use two heating elements, top and bottom. When hot water disappears, it's usually because the heat source lost power or flame, not because the tank itself failed.
A useful clue: if you get lukewarm water that runs out fast, an electric heater's upper or lower element may have failed. If it's completely cold, look at power or the pilot first.
Why the hot water stopped
Electric water heaters have their own breaker and a high-temperature reset button inside.
A draft, a dirty thermocouple or a gas supply hiccup can put out the pilot light.
If the water is lukewarm or runs out quickly on an electric heater, one of the two elements likely burned out.
Minerals settle in the bottom of the tank, which cuts capacity and makes popping or rumbling sounds.
| If you have | Check first | Then |
|---|---|---|
| Gas heater | Is the pilot lit? Look through the small window near the bottom. | Relight following the label, or call if it won't stay lit. |
| Electric heater | Is the breaker tripped? It's usually a double breaker. | With the breaker off, press the red reset button behind the upper panel. |
| Either type, water just lukewarm | The thermostat setting | About 120°F. Then think sediment or a failed element. |
| Either type, water on the floor | Leaks | Turn off power or gas and see the leak guide. |
Work through the checks
- Figure out gas or electricGas heaters have a gas line and a flue pipe on top. Electric ones have a thick cable going into a box on top and no flue.
- Electric: check the breakerWater heaters usually have a double breaker labeled "water heater" or "WH". If it's tripped, push it fully off, then on. Some heaters also have a red reset button behind the upper access panel; turn the breaker off before you open it.
- Gas: check the pilotLook through the small window near the bottom. If there's no flame, first make sure the gas valve on the supply line is open, then relight it by following the instructions on the label on the heater, step by step. If you smell gas, don't relight anything; leave and call the gas company.
- Check the temperature settingDials get bumped, especially on heaters tucked in a garage or closet. Safety agencies commonly suggest about 120°F to reduce the risk of scalding; your heater's label and manual show its own settings.
- Give it timeAfter fixing power or the pilot, a full tank takes 30 to 60 minutes (gas) or 60 to 90 minutes (electric) to heat up.
Watch it done
- The breaker is on, or the pilot flame shows in the window
- The dial is at the setting you chose
- Hot water at the tap after 30 to 60 minutes (gas) or 60 to 90 minutes (electric)
Pilot won't stay lit? Stop and call a pro. If you smell gas, leave and call the gas company.
If the water stays cold
If the pilot won't stay lit after relighting, the thermocouple is probably bad. It's an inexpensive part, but it's a job for someone comfortable working on gas appliances.
If hot water runs out much faster than it used to, flushing the tank can help.
What a pro typically charges (a rough estimate; prices vary by area): Water heater repairs typically run $150–$600. A new tank water heater installed usually costs $1,200–$2,500.
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