Why Is My Water Heater Leaking and Not Making Hot Water?
When a water heater is leaking and there's no hot water, the leak usually caused the outage. On gas tanks, water dripping onto the burner can put out the flame. On electric tanks, a leak can short an element and trip the breaker. Most often, both point to a tank that's rusting through, which means replacement.
Leaks and heating failures each have plenty of causes on their own. When they show up on the same day, the list gets much shorter. Water and burners don't mix, and water and wiring mix even worse. So the useful question isn't "what's wrong with the heater?" but "how did the water get to the part that heats?"
This post covers that link. If you only have a leak and the water is still hot, our top-to-bottom leak check is the better starting point. If the water is cold and the floor is dry, our no hot water repair page covers pilots, breakers, elements and tankless codes.
What to Do First
- Check for gas. A rotten-egg smell means everyone goes outside first; phone 911 and Southwest Gas or your propane company from there. Do nothing else.
- Shut off the heat source. Turn a gas control to Off, or switch off the double-pole breaker for an electric heater. Don't stand in water to reach a breaker panel.
- Close the cold-water valve on top of the heater to stop more water feeding the leak. Our shut-off guide shows where each control is.
- Don't relight or reset. Relighting a soaked burner or pressing an electric reset button while water is still reaching the wiring can make things worse, and it won't last.
- Look and photograph. Note where the water is coming from, take photos of the heater and its rating label, and protect the floor.
Safety: If hot water or steam is blasting from the relief valve pipe, stay clear of the pipe's outlet. Shut off the gas or power from a safe spot and call. Never cap or plug the relief valve.
Gas Tanks: The Leak Put Out the Flame
On a gas water heater, the burner sits under the tank at the very bottom. That's exactly where leaking water ends up.
Can a leaking tank put out the pilot light?
Yes, and it's one of the most common versions of this problem. When the tank rusts through at the bottom or along the flue, water drips straight down onto the burner. You may hear sizzling for days before the pilot finally goes out. Rust flakes falling with the water are another sign. A tank leaking onto its own burner has failed, so this one ends in replacement. Our page on a water heater tank leaking explains why tanks can't be patched.
What if the leak came from above and soaked the burner?
A drip from a fitting or the relief valve can run down the jacket and into the burner area. Once the fitting is fixed and things dry out, the burner may light again. But on newer gas heaters, the bottom has a sealed combustion chamber with a flame arrestor screen. If that screen gets wet and clogged with rust or mineral crust, the burner can be starved of air and refuse to stay lit. Some models also have a thermal switch that trips and has to be replaced. That's a parts job for a tech, covered on our gas water heater repair page.
Could it just be condensation?
Condensation can drip and sizzle on a cold morning, but it doesn't usually put the flame out on a heater that's sized and vented right. If the pilot is out and there's real water on the floor, treat it as a leak until proven otherwise.
Electric Tanks: The Leak Tripped the Power
Electric elements screw into the side of the tank behind small access panels, each sealed with a gasket. That makes them a common leak point and a common failure point at the same time.
Why did my breaker trip when the water heater started leaking?
If an element gasket leaks, water can run into the wiring compartment behind the panel. Wet wiring or a shorted element can trip the 240-volt breaker or the high-limit reset. A leak from a fitting above can do the same if it runs down inside the jacket. In those cases, a new gasket or element and a dry compartment may be all it needs, on a tank that's otherwise sound.
And if the insulation behind the panel is soaked?
Wet insulation behind the access panel with a dry element usually means the tank itself is leaking behind the jacket. That's not a gasket problem. The heater needs replacing. Our electric water heater repair page covers elements, gaskets and the safe reset steps once the leak is dealt with.
The Relief Valve Dumped Hot Water
This one runs the other way. Instead of the leak stopping the heat, too much heat causes the leak.
If a gas control valve or electric thermostat sticks on, the water keeps heating past its setting. The temperature and pressure relief valve opens to release it, and hot water pours from the side pipe. On an electric unit, the high-limit switch may then cut power, so you end up with a wet floor and a tank that's gone cold. You might notice the taps ran scalding hot just before.
That's the relief valve doing its job, and the fix is the control that failed, not the valve. Shut off the gas or power and call. A relief valve that drips now and then for other reasons, such as thermal expansion, is a different issue covered on our relief valve leaking page.
Tankless Units: Leak Plus Shutdown
Without a tank there's nothing to rust through, yet a tankless unit can still leak and quit heating together. Water leaking inside the cabinet can reach the control board or sensors, and many units shut down and show an error code when that happens. A heat exchanger split by a freeze, or a fitting at the isolation valves, are common sources. Scale from hard water can also stress parts over time.
Shut off the gas or power and the water valves under the unit, and don't keep power-cycling it. Our tankless water heater repair service covers leaks, error codes and descaling.
Why This Combination Often Means a New Heater
Not every case ends in replacement. A leaking element gasket, a fitting that dripped onto the burner, or a stuck thermostat can all be repaired on a tank that's still sound. But the odds tilt toward replacement for three reasons:
- The most common cause is a failed tank. Water from the tank onto the burner or into the insulation means the steel is rusting through.
- Repairs can stack up. A soaked burner, a clogged flame arrestor, a damaged control and a leaking fitting on the same older heater can add up close to the cost of a new one.
- Age is usually against it. Hard local water means many tanks run into trouble by year 7 to 9, and a heater that fails both ways at once is often in that range or past it.
For context, Angi puts the Apache Junction average for installing or replacing a water heater at about $1,136, with most jobs from $819 to $1,320. Our repair or replace guide helps you weigh a fix against that, and our replacement service page explains the visit.
If the leak reached walls, carpet or a mobile-home floor, read our post on water damage after a heater leak. For more homeowner answers, browse the water heater FAQ, or call Apache Junction Water Heater Pros at +1 480-863-0807 for leak repair in Apache Junction, day or night.
Leaking With No Hot Water: FAQs
Can I keep using a water heater that leaks and won't heat?
No. With no heat, the heater isn't doing its job, and a leak that reached the burner or wiring makes restarting it unsafe. Shut off the gas or power and the cold-water supply, then have the source found. Running it on and off while it leaks can damage controls and the floor, and a failing tank can get worse quickly.
Why did my pilot go out and now there's a puddle under the heater?
The two are often linked. Water dripping from a rusting tank or a fitting above can land on the burner and put out the pilot. The puddle is the same water. Look for rust flakes or water coming from under the tank. If the water is coming from the tank itself, the heater needs replacing rather than a relight.
What should I tell you when I call about a leak and no hot water?
Say whether the heater is gas or electric, where the water is coming from, and what stopped: a pilot that went out, a breaker that tripped, or a tankless code on the display. A photo of the rating label helps us bring the right parts. Let us know if you've already shut off the cold water and the heat.
My water heater was scalding hot, then leaked and went cold. What happened?
That pattern often means a thermostat or gas control stuck on and overheated the water. The relief valve opened to release the heat and pressure, which caused the leak. On electric units the high-limit switch may then cut power. It needs a tech to replace the failed control, and the relief valve should be checked too.
Can hard water cause a leak and a cold tank at the same time?
It can speed both up. In water this hard, sediment piles up on the bottom of a gas tank, so the steel under it runs hotter and can wear through sooner. On electric tanks, scale builds on the lower element until it burns out. A tank that has never been flushed is more likely to fail both ways, often around the same age.