It’s Friday night, and someone heads to the shower—then comes the dreaded message no father wants to hear: “We don’t have any hot water.”
You sigh and think, Why does this always happen on a weekend? Hopefully, it’s just the pilot light going out due to a routine fluctuation in gas pressure. Maybe the utility company was working on the city side and had to briefly cut the gas.

In situations like this, the best-case scenario is a simple one: the pilot light went out and just needs to be relit—with minimal disruption.
Many people go through life never needing to relight a pilot light. But if you’re not one of them, here’s some helpful info on how to do it safely on a gas-powered water heater.

What Is a Pilot Light?

First off, you might be asking yourself: What is a pilot light? Simply put, it’s a small, continuously burning flame—usually blue—that stays lit 24/7. When the water heater kicks on to heat the water, it uses this flame to ignite the gas.

Sometimes you’ll hear a “whoosh” or rushing sound—that’s the heater releasing gas into the burner, where it’s then ignited by the pilot flame. If the pilot flame goes out gas will stop flowing to the pilot and the water heater shuts down.

How to Light a Water Heater Pilot Light

Every make and model is a little different and its best to follow the manual that came with your water heater. If you can’t find the manual, instructions are easy to find online for most water heaters. The guide will serve as general information that will work on most modern day heaters.

Always refer to the manufacturer’s instructions for your specific water heater model, as procedures can vary. However, most gas water heaters follow a similar relighting process. Here’s a general guide to help you through it:

Turn Off the Gas Supply
Locate the gas shut-off valve, typically found near the bottom front of the unit. Turn the knob to the “Off” position and wait at least five minutes to allow any residual gas to dissipate.

Access the Pilot Light
Open the access panel or door beneath the gas control valve. On some models, this may be an open slot instead of a removable cover.

Locate the Burner
Use a flashlight to peer inside. Look for the burner, which is connected to two small gas tubes. Keep your eyes on this area as you proceed.

Set to Pilot Mode
Turn the gas control knob to the “Pilot” setting. Press and hold the knob to allow gas to flow. On some units, you may also need to press a separate red button to initiate pilot mode.

Light the Pilot
While holding the gas control, ignite the pilot. This may be done using a built-in igniter (a red or black button) or with a long lighter for manual ignition.

Hold and Check the Flame
Once lit, continue holding the gas knob or button for about 60 seconds. Slowly release it and confirm that the flame stays on.

Turn the Gas On
Rotate the knob to the “On” position. You should hear a “whoosh” or soft “whump” as the main burner ignites.

Close the Access Panel
Replace the cover and enjoy your hot water.

If your pilot light goes out repeatedly, it may be more than just a pressure fluctuation. A common culprit is a dirty or misaligned thermocouple—the small copper rod that detects the flame and shuts off the gas if it goes out.

Troubleshooting a Faulty Thermocouple or Flame Sensor

In many modern water heaters, the thermocouple is now called a flame sensor. If your pilot light keeps going out—even after relighting it correctly—you’re likely dealing with a flame sensor that’s dirty, damaged, or out of position.

If it’s bent away from the burner, start by turning off the gas supply. Gently reposition the sensor closer to the flame, then try relighting the pilot.

Still no luck? It may just need a good cleaning. First, shut off the gas at both the heater’s control valve and the main gas line nearby. Next, remove the three nuts that secure the flame sensor and gas tubes to the control valve. The burner assembly should slide out easily.

Use a vacuum to clean the burner ports, then gently scrub the tip of the flame sensor with steel wool and a microfiber cloth. If cleaning doesn’t fix the issue, replacement sensors are inexpensive—usually under $15 at your local hardware store.