Before you call, check the breaker or gas supply, confirm other gas appliances work, look at the thermostat setting, and see whether the pilot is out on a gas unit or the high-limit reset has tripped on an electric one. If you smell gas, see water on the floor, or a breaker keeps tripping, stop and call a plumber.
Key takeaways
- A tripped breaker, a closed gas valve, or a thermostat bumped to vacation mode are the most common reasons for no hot water.
- On a gas heater, a pilot that won't stay lit usually means a worn thermocouple, which is a repair, not a replacement.
- On an electric heater, the red high-limit reset button under the upper panel trips when a thermostat or element fails.
- Hot water that runs out fast or turns lukewarm points to sediment, a broken dip tube, or one dead element.
- Never remove electric panels without shutting the breaker off, and never relight a pilot if you smell gas.
What are the quick checks anyone can do?
Start with the boring stuff. It solves the problem more often than you'd guess, and it takes two minutes.
- Electric heater: find its breaker in the panel. If it's tripped, flip it fully off, then on. If it trips again, stop there.
- Gas heater: make sure the gas valve handle on the pipe is in line with the pipe (open). Check that the stove or furnace also works, so you know gas is reaching the house.
- Look at the thermostat dial or control screen. Someone may have turned it down or set vacation mode.
- Run the hot tap for a full minute. In a big house it takes time for hot water to reach the far bathroom.
- Look under and around the heater for water. A puddle changes everything; skip to the last section.
- Sniff. If you smell gas anywhere near the unit, leave and follow the steps in our gas smell guide.
Gas water heater: what should I look at?
Most gas heaters have a small window near the bottom where you can see the pilot flame. No flame means the pilot is out. Newer units show a blinking status light instead, and the label on the unit explains what the blink pattern means. Relighting the pilot is fine to try if the instructions are printed on the tank and you don't smell gas. Follow them exactly and wait the full time it asks for before trying again.
If the pilot lights but goes out as soon as you let go of the button, the thermocouple is the usual suspect. That's the small sensor that sits in the pilot flame and tells the gas valve it's safe to stay open. They wear out, and swapping one is a normal repair. A pilot that lights, stays lit, but the main burner never fires points to the gas control valve or a safety sensor, and that's ours to diagnose.
Electric water heater: what should I look at?
Electric heaters have two panels on the side, an upper and a lower, each covering a thermostat and a heating element. Behind the upper panel is a red reset button on the high-limit switch. It trips when the water gets too hot, which usually means a thermostat stuck on or an element shorting. Shut the breaker off first, remove the panel and the insulation behind it, press the button firmly, put everything back, and turn the breaker on.
If the reset trips again within a day, don't keep pressing it. Something is failing and it needs testing with a meter. Elements and thermostats are inexpensive parts, but finding which one is bad requires checking them under power, which isn't a homeowner job. Two other electric clues: lukewarm water that never gets hot often means the lower element is dead, and water that's hot briefly then cold means the upper one is.
Why is my hot water lukewarm or running out fast?
If you have some hot water but not enough, the heater is working and something else is off. Sediment on the bottom of a tank takes up space that should hold hot water and insulates the burner from it, so the tank heats less and slower. A flush can help. A broken dip tube, the plastic pipe that sends cold water to the bottom of the tank, lets cold water mix in at the top, and you get lukewarm water almost right away.
A thermostat that drifted low or was set low on purpose is easy to correct; the U.S. Department of Energy recommends 120°F for most homes. On a tankless unit, lukewarm water or short bursts of cold usually mean scale in the heat exchanger or a flow rate above what the unit can handle. Check the display for an error code and write it down before you call.
When should I stop troubleshooting and call?
Some things aren't worth pushing on. Call right away if you see water pooling under the tank, if a breaker trips more than once, if the pilot won't stay lit after one careful relight, if the T&P relief valve on the side is dripping steadily, or if you smell gas or see scorching around the burner or vent. Those are signs of a failing tank, a bad part, or a combustion problem, and each one needs a licensed plumber.
When you call us, tell us the fuel type, roughly how old the unit is, and what you already tried. That helps us bring the right parts. We offer 24-hour emergency service, and once we're there we'll show you what failed and give you options, whether it's a quick part swap or a conversation about replacement. No high-pressure sales.
People also ask
Is it safe to relight the pilot on my water heater myself?
Why does my breaker trip when the water heater turns on?
My tankless water heater shows an error code. What now?
References: U.S. Department of Energy. Requirements vary by municipality and change over time; confirm current rules with the authority having jurisdiction.