What Is a Pilot Light and Why Does It Go Out?

A pilot light is a small, continuously burning flame inside your gas water heater. It serves one critical purpose: igniting the main gas burner whenever the thermostat calls for heat. When the pilot light goes out, the burner can't fire, and you're left without hot water.

Pilot lights can go out for several reasons:

Drafts — Wind from nearby windows, doors, or vents can blow out the flame
Dirty thermocouple — The safety sensor near the pilot can get coated in soot, causing it to shut off the gas
Faulty thermocouple — A worn-out thermocouple may incorrectly signal that the pilot is out
Gas supply interruption — A temporary interruption or a partially closed valve
Clogged pilot tube — Dust or debris blocking the small gas line to the pilot

The good news is that relighting a pilot light is usually a simple process that takes about 15-30 minutes. Here's how to do it safely.

Before You Start: Safety Precautions

Gas appliances require extra caution. Follow these safety rules before attempting to relight your pilot light:

Smell the area carefully. If you detect a strong rotten egg or sulfur smell, do NOT attempt to relight. This indicates a gas leak.
If you smell gas: Turn off the gas valve immediately, do not flip any electrical switches, open windows and doors, leave the house, and call your gas company or fire department from outside.
Ensure good ventilation. Open a window or door near the water heater.
Clear the area. Remove any flammable materials, rags, or chemicals from around the water heater.
Read your owner's manual. Your water heater may have model-specific instructions printed on the label or in the manual.

What You'll Need

A flashlight to see inside the access panel
A long-reach lighter or long matches (for older models without an igniter)
A screwdriver (if the access panel has screws)

Most water heaters built after 2010 have a built-in piezo igniter, so you likely won't need a lighter at all.

Step-by-Step: How to Relight Your Pilot Light

Step 1: Turn Off the Gas Control

Locate the gas control valve on your water heater. It's typically a box-shaped device near the bottom of the tank with a dial that has three positions: ON, OFF, and PILOT.

Turn the dial to the "OFF" position. This stops all gas flow to the unit.

Wait at least 10 minutes. This is critical — it allows any residual gas in the combustion chamber to safely dissipate. Don't skip this step.

Step 2: Find the Pilot Light Assembly

Look at the bottom of your water heater for a small access panel or viewing window. Some models have a removable metal cover held by screws or clips; others have a clear window you can look through.

Use a flashlight to locate the pilot light assembly inside. You'll see a small metal tube (the pilot tube) aimed at the burner assembly.

Step 3: Set the Dial to "PILOT"

Turn the gas control dial to the "PILOT" position. On most models, you'll also need to push the dial inward (about a quarter inch) to allow gas to flow to the pilot tube only.

Step 4: Light the Pilot

If your water heater has an igniter button (most modern models):

Press and hold the gas control dial in the pushed-in position
While holding the dial, press the igniter button repeatedly (usually a red or black button nearby)
You should see a spark through the viewing window, followed by a small flame
Continue holding the dial in for 30-60 seconds after the flame lights — this allows the thermocouple to heat up enough to keep the gas valve open

If your water heater does NOT have an igniter (older models):

Press and hold the gas control dial in the pushed-in position
While holding, carefully bring a long-reach lighter or long match to the pilot opening
Light the pilot flame
Continue holding the dial for 30-60 seconds

Step 5: Release and Check

After holding the dial for 30-60 seconds, slowly release it. The pilot flame should remain lit on its own.

If the flame goes out: Wait 5 minutes, then repeat the process from Step 3. It sometimes takes two or three tries, especially if air got into the gas line.

Step 6: Turn the Gas to "ON"

Once the pilot light is burning steadily, turn the gas control dial from "PILOT" to "ON." You should hear a soft whooshing sound — that's the main burner igniting. This is normal.

Replace the access panel if you removed one.

Step 7: Set Your Temperature

Adjust the temperature dial to your preferred setting. The recommended setting is 120°F for the best balance of comfort, safety, and energy efficiency.

Your hot water should be fully restored within 30-40 minutes.

What a Healthy Pilot Flame Looks Like

A properly burning pilot light should be:

Blue with a small yellow tip — this indicates clean, efficient combustion
Steady — not flickering wildly or wavering
Touching the thermocouple — the flame should be making contact with the tip of the thermocouple sensor

Warning signs of a problem:

Yellow or orange flame — indicates incomplete combustion, possibly due to insufficient air supply or a dirty burner
Weak or small flame — may mean a clogged pilot tube or low gas pressure
Flame that flickers excessively — could indicate a draft problem or a failing thermocouple

Pilot Light Won't Stay Lit? Common Causes

If your pilot light keeps going out after relighting, there's likely an underlying issue:

Dirty or Faulty Thermocouple

The thermocouple is a safety device that detects whether the pilot light is burning. If it can't sense the flame (due to dirt or wear), it shuts off the gas supply as a safety measure.

Fix: Gently clean the thermocouple tip with fine sandpaper or steel wool. If cleaning doesn't help, the thermocouple may need to be replaced — an inexpensive part (usually under $20) that a handy homeowner can install or a plumber can replace quickly.

Draft or Ventilation Issues

Strong air currents near your water heater can repeatedly blow out the pilot light.

Fix: Check for open windows, gaps in walls, or HVAC vents blowing directly toward the water heater. Consider adding a draft shield if drafts are persistent.

Clogged Pilot Tube

Dust, dirt, or spider webs can partially block the small tube that feeds gas to the pilot light, resulting in a weak flame that won't sustain itself.

Fix: A professional can clean or replace the pilot tube. Do not attempt to clear it with compressed air while gas is connected.

Failing Gas Control Valve

In older water heaters, the gas control valve itself can wear out and fail to hold gas flow to the pilot.

Fix: This typically requires professional replacement of the gas valve assembly. See our gas water heater ignition troubleshooting guide for more detailed diagnostics.

Modern Water Heaters: No Pilot Light?

If your water heater was manufactured after approximately 2010, it may not have a traditional standing pilot light at all. Many modern gas water heaters use electronic ignition systems instead:

Hot surface igniter (HSI) — A ceramic element that glows red-hot to ignite the gas
Spark igniter — Creates an electric spark to light the burner on demand

These systems are more energy-efficient since they don't burn gas continuously. If your water heater has electronic ignition and isn't working, the issue may be electrical rather than a pilot light problem. Check your circuit breaker and consult your owner's manual.

When to Call a Professional

While relighting a pilot light is generally safe for homeowners, call a licensed plumber or gas technician if:

You smell gas at any point during the process
The pilot light won't stay lit after three or more attempts
The pilot flame is yellow, orange, or excessively weak
You hear hissing near the gas connections
Your water heater has electronic ignition and won't fire
You see signs of soot, scorching, or carbon buildup around the burner area
You simply aren't comfortable working with gas appliances

How Old Is Your Water Heater?

If your pilot light keeps going out or your water heater is giving you repeated trouble, it might be nearing the end of its lifespan. Most gas water heaters last 8-12 years. If yours is getting up there in age, replacement may be more cost-effective than ongoing repairs.

Not sure how old your unit is? Use our free Water Heater Age Checker to find out instantly — just enter your brand and serial number.

How to Relight a Water Heater Pilot Light Safely