No hot water? Here’s how to fix it

Have you ever lathered up a headful of shampoo, only to have your luxurious hot shower turn into a cold rain? When your water heater suddenly stops working, you realize just how important it is. 

If you have no hot water at all, you can often restart the heater by yourself. Handy homeowners can learn how to relight a gas pilot light or reset an electric water heater.

But if you can’t fix it—or if you have other problems, such as hot water that turns cold quickly, or comes out lukewarm or rust-colored—you’ll need to call a water heater repair service pronto. And if a pro can’t repair the issue, your water heater may be one of the 7 million that need replacing every year.

In this article, you’ll learn how a typical tank water heater operates, simple DIY resets, and how to get help when you need it. 

Need a pro? Read How to find a good plumber and 15 questions to ask a plumber before hiring.

Here are some basics to get you started:

A conventional water heater is essentially a large, cylindrical tank with a gas or electric energy source that’s filled through a cold-water supply pipe. The pipe typically has a shutoff inlet valve just before it gets to the tank, which lets you turn off water for repairs or maintenance. 

Water temperature is set by a thermostat, which is located on the main controls of a gas heater or the heating elements of an electric heater. 

At the top of a water heater tank, there’s a pressure-relief valve that automatically lets out steam if the tank gets too hot. At the bottom, a valve can be opened to drain the water or flush mineral sediment from the tank during yearly maintenance.

There are key differences between gas and electric appliances that affect troubleshooting and repair—so it’s important to know which type of water heater you have. 

Need professional repairs? Read Water heater repair cost guide.

A conventional gas water heater has a flue (vent pipe) at the top to release toxic combustion gases outside—usually through the roof. Electric water heaters don’t need a flue.

A natural gas water heater also has a gas-supply line that goes to a pipe with its own shutoff valve. From there, it goes to a valve on the water heater that controls the pilot light and water temperature. Liquid propane (LP) water heaters work the same way, but deliver gas from a propane tank.

An electric-heated model will have an electric cable or conduit that connects the power source to terminals on the tank. It also has two heating elements, placed one above the other, behind raised access panels. (Small heaters may only have one.)  Each element has its own thermostat, but the upper one must be working for the lower one to heat.

Safety tip: Always turn off the power before working on an electric water heater! 

With a bit of knowhow, you may be able to take care of certain water-heater issues on your own. Here’s what to do for the most common problems.

For a liquid propane (LP) water heater, the first thing to check is the gas level in the propane tank outside. If it’s low, have it refilled.

If your LP or natural gas water heater isn’t working, it’s possible that the pilot light has gone out. This can happen if the gas supply was interrupted, the valve was turned off, or a gust of wind blew it out.

Look through the window behind the access cover at the bottom of the water heater. If you see a very small flame—the pilot light—the problem is something else. Call a water heater service pro.

If the pilot light is out, “it really pays to know how to relight it,” says home improvement expert Don Vandervort of HomeTips.com. “This can save you the cost and inconvenience of a service call and get your hot water working immediately.”

Relighting instructions are usually in your owner’s manual or posted on the water heater itself. They can vary, but this is the typical step-by-step sequence:

If the flame doesn’t stay lit, repeat the process. If it won’t stay lit after a couple of tries, there may be a problem with a part called a thermocouple. Call a pro to replace it, which usually costs $100–150.

When your electric heater isn’t providing hot water, try the following fixes.

Reset the circuit breaker:

If the circuit breaker isn’t the problem, press the reset button:

Check the temperature dial to make sure it’s set hot enough. If it’s set too low, raise the temperature gradually and test it over a day or two, so the water doesn’t become scalding.

If lukewarm water is a chronic problem, try increasing the temperature settings on the heating elements:

If the problem continues, call a water heater pro. The upper heating element probably needs to be replaced, which typically costs $200–300.

If this just started happening with an electric water heater, the lower heating element may have failed and needs to be replaced. Call a water heater pro and expect a charge of $200–300.

But if it’s a chronic problem, with either an electric or gas water heater, there’s a good chance your water heater isn’t large enough or has a too-slow recovery time. Consider replacing the appliance with a larger model or buying a tankless heater that never runs out.

Water heaters typically have a lifespan of 10–20 years; average age at replacement is 13 years, according to Energystar.gov. Older models tend to be energy hogs, too—on average, existing water heaters account for 12% of a home’s overall energy consumption. So replacing an old water heater—especially if it’s electric—with a newer and more energy-efficient model is a great way to reduce your utility bill. 

Some problems—notably those that suggest a failing tank—are either irreparable or so serious that it may not be worth trying to save the water heater. 

Common reasons to suspect an unsound tank:

If the appliance is more than 8 years old, start preparing for replacement. “It doesn’t pay to wait until your water heater dies,” says Don Vandervort. “When it fails, it can cause water damage and you’ll be stuck without hot water—leaving you virtually no time to make an informed decision about its replacement. Do your research ahead of time.”

Need a replacement? Read Water heater installation cost guide.

“I wanted to repair an old water heater before it failed, so I scheduled a visit for an estimate [with Joe’s 2 Sons Plumbing in Seattle],” says Allan L. of Bothell, Washington. “A few days later, my old water heater started leaking. Called up and explained the situation.… Mike went to the plumbing supply store to get a new water heater and installed it, all within 1.5–2 hours.”

“Woke up this morning to a rusted floor of my water heater,” says Michael F. of Olathe, Kansas. “I went through Home Depot because I have an account there. They contracted with True Blue Plumbing in Kansas City, Missouri, for the install, and I’m glad they did. [A] complete professional explained everything he was having to do step-by-step and why he was doing it. Gave me some tips on what to do to prolong the life of my house and my equipment.” 

“I had a gas water heater start sputtering and coughing while I was taking a shower,” says Rob C. of Berkeley. “I called Water Heater Masters in Concord, California, [and] at 8 am the next day the certified tech… took one look at the video I had shot of the noise and knew exactly what the problem was…. He recommended that I replace the burner assembly unit (and gave me tips on how to replace it). … I reinstalled and fired up the heater. It worked.”

Find a water heater service professional in your area.