Relighting a pilot light on a gas water heater is a common household task, but it must be done with serious attention to safety. Before you reach for a lighter, understand the risks: natural gas is flammable, and a faulty relight can lead to gas leaks, fires, or even explosions. This guide walks you through the entire process, explaining how your water heater’s pilot system works, what safety checks to perform, and how to diagnose problems that may prevent the pilot from staying lit. Follow these steps carefully, and if you ever hesitate, call a licensed professional.

How the Pilot Light System Works

The pilot light is a small, continuously burning flame that sits inside the burner chamber of a gas water heater. Its job is to ignite the main burner when the thermostat calls for heat. The system relies on a thermocouple, a heat-sensitive safety device. The thermocouple sits in the pilot flame and generates a small electrical current that keeps the gas valve open. If the pilot goes out, the thermocouple cools down, the voltage stops, and the gas valve closes automatically—preventing unburned gas from leaking into your home.

Modern water heaters also incorporate a flame arrestor and a gas control valve. Some models use an electronic ignition instead of a standing pilot, but most traditional tanks still have a standing pilot. The steps below apply to standing pilot systems. If your water heater has an electronic igniter, refer to the manufacturer’s instructions or call a professional.

Safety Preparation Before Relighting

Safety is not optional. Before you do anything, prepare the area and yourself.

  • Turn off the gas supply at the shutoff valve on the gas line feeding the water heater. Usually this is a small lever; turn it so it is perpendicular to the pipe.
  • Wait at least 5 minutes after turning off the gas. This allows any accumulated gas in the burner chamber to dissipate. If you smell gas during this time, leave the area immediately, do not use any electrical switches or flames, and call your gas company from outside.
  • Ventilate the room. Open windows or doors near the water heater to increase air circulation.
  • Gather your tools: a long-reach butane lighter or fireplace match (never use a cigarette lighter that requires you to put your hand close), protective gloves, and safety goggles if desired. Also have a flashlight handy to inspect the burner area.
  • Read your water heater’s manual. Different brands have slightly different pilot assemblies. The manual will tell you if your model has a pilot button that must be held down, or if it uses a different reset procedure.

Critical warning: If you ever smell gas after turning the gas back on, or if the pilot flame is yellow or lifting off the thermocouple, do not try to relight again. Shut off the gas and call a professional.

Step-by-Step Relighting Procedure

Follow these steps in order. Do not skip any.

1. Locate the Pilot Light Assembly

Remove the access panel(s) at the bottom front of the water heater. You will see a small gas line (the pilot tube), the thermocouple wire, and the main burner tube. The pilot light assembly is usually positioned near the thermocouple. Some models have a small observation window or a slot where you can insert the lighter.

2. Turn the Gas Control Knob to “Off”

Find the gas control valve (usually a knob with markings for Off, Pilot, and On). Turn it fully to Off. Do not apply excessive force. Wait at least 5 minutes (some manufacturers recommend 10 minutes) to allow any residual gas to clear. Use this time to inspect the area for any signs of gas smell.

3. Set the Knob to “Pilot” and Hold the Reset Button

After the wait, turn the knob to Pilot. Many valves require you to push and hold a red or black button (often labeled “Reset” or “Pilot”) while lighting. If your model has this button, you will need to hold it down continuously to allow gas to flow to the pilot tube.

4. Light the Pilot

With the button held down (if applicable), use your long lighter or match to ignite the pilot through the access opening. Aim the flame directly at the pilot tube opening. You should see a small blue flame appear. Continue holding the reset button for about 30 seconds after the pilot lights. This gives the thermocouple time to heat up and generate enough voltage to keep the gas valve open.

Important: If the pilot does not light within a few seconds, release the reset button, turn the gas knob to Off, wait 5 minutes, and try again. Do not keep the gas flowing if the pilot won’t light—this can release raw gas.

5. Release the Button and Verify the Pilot Stays Lit

After 30 seconds, slowly release the reset button. The pilot flame should remain burning. If it goes out, the thermocouple is likely not sensing enough heat. This could mean the thermocouple is dirty, worn out, or not positioned correctly in the flame. If the pilot goes out, turn the knob to Off, wait, and try again—if it fails repeatedly, you need professional service.

6. Turn the Gas Control Knob to “On”

Once the pilot stays lit on its own, turn the knob from Pilot to On. You should hear the main burner ignite within a few seconds if the thermostat is calling for heat. Listen for a steady, low roar. Check that the pilot flame remains lit and does not change appearance.

7. Replace the Access Panels

After confirming everything is working, replace the access panels securely. Do not block the airflow openings at the top or bottom of the water heater.

What to Check If the Pilot Won’t Stay Lit

If your pilot light repeatedly goes out after relighting, or if it doesn’t light at all, consider these common issues:

  • Dirty or damaged thermocouple: Over time, the thermocouple can accumulate soot or become bent. Gently clean the tip with fine steel wool or replace it. The thermocouple is a cheap part and easy to swap on most models.
  • Clogged pilot orifice: A tiny particle can block the gas flow to the pilot. Use compressed air or a fine wire to clear the orifice. Turn off the gas before doing this.
  • Weak or failing gas control valve: If the valve itself is defective, it may not allow gas to flow even when the pilot is lit. This requires replacement by a technician.
  • Draft or downdraft: A strong draft from a nearby vent or open door can blow out the pilot. Install a draft diverter or close windows near the water heater.
  • Thermocouple not in the flame: Verify that the tip of the thermocouple is positioned directly in the pilot flame. If it’s misaligned, gently bend it back into place.

For a more comprehensive troubleshooting guide, see Energy.gov’s water heating tips. Also consult your manufacturer’s manual—many brands like Rheem, AO Smith, and Bradford White have detailed online resources.

Pilot Light Flame Appearance Guide

The color and shape of your pilot flame tell you a lot about combustion quality.

Flame Appearance Meaning Action
Steady blue with a yellow tip Normal None
All yellow or orange Poor combustion; may indicate dust, lint, or a blocked air intake Clean the burner and pilot area
Lifting off or fluttering Excessive draft or gas pressure too high Check for drafts; call a professional if pressure is suspected
Very small or weak Clogged pilot orifice or low gas supply Clean orifice; check gas valve

When to Call a Professional Immediately

Do not attempt to relight the pilot—or even troubleshoot—in these situations:

  • You smell gas continuously even after turning off the supply. Leave the building and call the gas company from outside.
  • You see signs of a gas leak (hissing sound, bubbles on gas lines, rotten egg odor).
  • The water heater has been flooded or exposed to water. Internal electrical components may have shorted.
  • You cannot access the pilot assembly because of corrosion or physical blockage.
  • The pilot lights but the main burner never ignites. This could be a faulty thermostat or gas valve.
  • You’re unsure about any step. A licensed plumber or HVAC technician can safely relight and inspect your system.

Regular professional maintenance—including thermocouple replacement and burner cleaning—can prevent most pilot light problems. The American Gas Association recommends an annual inspection of gas appliances. For more information, see AGA’s home safety resources.

Preventive Maintenance to Avoid Pilot Light Issues

You can extend the life of your water heater and reduce pilot light failures with a few simple habits:

  • Keep the area around the water heater clean. Dust and lint can clog the pilot orifice or burner.
  • Check the pilot flame monthly. If it’s ever erratic, clean the assembly before it goes out.
  • Test the temperature-pressure relief valve annually.
  • Drain a few gallons of water from the tank every 6 months to remove sediment buildup, which can affect burner efficiency.
  • Ensure there are no flammable materials (boxes, chemicals, gasoline) within 3 feet of the water heater.

If you live in an area with hard water, consider installing a water softener to reduce mineral scale that can affect the thermocouple and gas valve.

Understanding Gas Shutoffs and Safety Valves

Every gas water heater has a safety shutoff device that stops gas flow if the pilot goes out. This is the thermocouple. If your pilot won’t stay lit, the thermocouple is the first thing to check. Replacing a thermocouple is a DIY-friendly job for many homeowners: it usually costs less than $20 and requires only simple hand tools. However, if you have any doubt, hire a professional. A miswired or loose thermocouple can cause a dangerous gas leak.

Some water heaters also have a flame lockout feature: after three failed attempts to light the pilot, the gas control valve enters a lockout mode that requires a reset. Check your manual for the reset procedure—often it involves turning the knob to Off for 30 seconds, then back to Pilot.

Final Checks After Relighting

Once you’ve successfully relit the pilot and turned the gas control to On, monitor the water heater for a few minutes. Listen for the main burner to fire up. Feel the gas line connections (using soapy water) for any bubbles that indicate a leak. If you see bubbles, tighten the connection or call a plumber. Ensure the water heater’s exhaust vent is properly drawing—place a piece of paper near the vent hood; the paper should be sucked toward the vent, not blown away.

Finally, note the date and the condition of the pilot flame. If you have to relight the pilot again within a few days, schedule a professional inspection. A pilot that frequently goes out is a sign of a deeper problem, such as a failing gas valve, a cracked heat exchanger, or a blocked vent.

Relighting a pilot light is a straightforward skill, but it demands respect for the risks involved. Follow the steps, trust your senses (if something smells off, stop), and know when to call for help. By maintaining your water heater and addressing small issues early, you can avoid cold showers and expensive emergency repairs.

For additional reference, see the U.S. Consumer Product Safety Commission guide on gas water heaters and your local utility’s safety information.