Check the pilot light on a gas water heater.

Have a problem with your hot water heater? With their plumbing pipes and gas lines or electric wires, water heaters may seem like complicated appliances. However, there is some simple DIY hot water heater troubleshooting you can try before you call a plumber or electrician.

Troubleshooting a Gas Hot Water Heater

If a gas hot water heater stops working, try sparking the pilot light. If it won’t stay lit, you may need to replace the thermocouple or clean the burner. Your owner’s manual should have straightforward instructions for replacing a thermocouple. On most models, you turn off the gas control knob and detach both ends of both the thermocouple and pilot supply line. Buy a same-length replacement, reinstall the thermocouple, turn the gas on and relight the pilot.

If you still aren’t getting any hot water, or if the pilot light is more yellow than blue, clean the burner. Turn off the gas and remove the thermocouple and pilot supply line. Also remove the burner tube and unclip the burner unit. It should look like a metal plate with a clamp on the bottom. Unscrew the burner and clean the pilot gas tube with a small wire brush or wire. Shake any debris off the burner plate and vacuum the gas tube.

Reassemble the unit, turn on the gas and light the pilot. If your hot water heater troubleshooting didn't solve the problem, it’s time to call a professional.

Troubleshooting an Electric Hot Water Heater

If you aren’t getting any hot water from an electric water heater, hit the reset button and wait for a click. If that fails, reset the electric breaker. The next step is to test and possibly replace the thermostat or heating element.

Water and electricity are a dangerous combination, so first drain the tank and switch off the power breaker. Then remove the access panel and test each terminal screw with a voltage tester. After confirming the power is off, loosen the terminal screws and pull the wires away from the end of the element. Loosen and unscrew each element, then have an appliance parts dealer test the part. Replace a broken element.

If the element is fine, the thermostat might be broken. The next step in hot water heater troubleshooting is to disconnect and mark the thermostat wires, then have the thermostat tested. Replace if necessary.

If Hard Water Won’t Get Hot

If the unit is set on high, but the water is not hot enough, try draining the tank and removing crusted minerals from the anode. Shut off the water and the power supply. Then attach a hose to the drain valve and drain the tank.

Look for a one-inch nut on the top of the heater. Loosen the nut and pull out the anode rod. If it is covered in mineral deposits, replace the rod. Refill the tank, then turn on the power supply. To prolong the life of the water heater, drain and refill the tank once a year if you have hard, mineral-laden water.

Try some hot water heater troubleshooting before calling in a professional. But also know when to throw in the towel. For example, if the heater leaks, the tank is probably rusted through and should be replaced.

Updated April 16, 2018.