If you suddenly have no hot water, the cause is usually simple: a tripped breaker or reset button on an electric water heater, or a pilot light that went out or a gas control problem on a gas model. Start by identifying your water heater type, then work through the checks below. If the tank is leaking or you smell gas, stop and get professional help.
Quick answers
- Electric: check the breaker, then the red reset button behind the upper access panel.
- Gas: check that the pilot is lit (older models) or read the status light (newer models).
- Lukewarm water: often a failed lower element (electric) or sediment buildup.
- Running out fast: see Hot Water Runs Out Fast.
- Smell gas: leave the home and call the gas utility from outside.
Step 1: Identify your water heater type
- Gas tank: has a gas pipe and a vent pipe on top. Look for a control knob with ON, OFF and PILOT.
- Electric tank: has a thick electrical cable and two access panels on the side, no vent pipe.
- Tankless: a box on the wall. See the manual for error codes.
- Heat pump water heater: a tall tank with a fan unit on top.
If you have an electric water heater
1. Check the breaker
Electric water heaters use a double-pole breaker, usually 30 amps. If it’s tripped, reset it once. If it trips again, call a technician or electrician: an element or the wiring may be shorted.
2. Press the reset button
With power off at the breaker, remove the upper access panel and insulation. Press the red high-limit reset button firmly. If it clicks, it had tripped. Replace the insulation and cover, then restore power. If it trips again, a thermostat or element may be failing.
3. Test the heating elements
Most electric tanks have two elements. If the upper element fails, you get no hot water. If the lower fails, you get a small amount of lukewarm water.
To test an element: turn the breaker off and confirm with a non-contact voltage tester that no power reaches the terminals. Disconnect one wire from the element and set a multimeter to ohms. A good element usually reads roughly 10 to 30 ohms (for example, about 13 ohms for a 4,500-watt, 240-volt element). A reading of zero or “OL” (open) means the element has failed. Replacing an element requires draining the tank below the element level. If you’re not comfortable working with 240-volt circuits, have a technician do it.
If you have a gas water heater
1. Check the gas supply
Make sure the gas valve on the supply pipe is open (handle parallel to the pipe) and that other gas appliances work.
2. Check the pilot or status light
- Older models: look through the small window at the bottom. If you don’t see a small blue flame, the pilot is out. Relight it following the instructions on the label on the tank.
- Newer models with electronic controls blink a status light. Count the blinks and check the label.
If the pilot won’t stay lit, see Water Heater Pilot Light Won’t Stay Lit.
3. Check the thermostat dial
Someone may have turned the gas control to VACATION or a low setting. The U.S. Department of Energy suggests 120°F as a good setting for most households.
4. Check for a tripped thermal cutoff
Many gas water heaters have a flammable vapor sensor or thermal switch. If it trips, the pilot won’t stay lit until the cause is addressed. This usually requires a technician or part replacement.
If the water is warm but not hot
- Thermostat set too low
- Failed lower element (electric)
- Heavy sediment in the tank reducing capacity (How to Flush a Water Heater)
- Broken dip tube mixing cold water into the hot outlet
- Cold weather increasing demand
If the tank is leaking
Turn off power or gas and the cold water supply valve. See Water Heater Leaking from the Bottom: What to Do Right Now.
When to replace instead of repair
If your tank water heater is more than about 10 years old and needs a major repair, replacement is often the better investment. See How Long Do Water Heaters Last? and Water Heater Replacement Cost.
Frequently asked questions
How long does it take a water heater to reheat?
A typical 40–50 gallon gas tank recovers in about 30–40 minutes; electric tanks often take longer, around 60–80 minutes.
Why do I have hot water in some faucets but not others?
That suggests a faucet or mixing valve problem, not the water heater.
Is it safe to relight a pilot light myself?
Yes, if you follow the instructions on the water heater label exactly and don’t smell gas. If you smell gas, don’t attempt it.