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Fix a water heater that will not light

We'll check gas supply and pilot orifice, then direct you to call a plumber for pilot and thermocouple work—gas pilot work requires a professional.

Troubleshooting · Home plumbing
10–20 min
What you'll need
  • Thin wire or needle (to clear pilot orifice only)
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Steps

Goal: Confirm the symptom, check gas supply and pilot orifice, then call a plumber for pilot work.

  • Check the label on the tank—it should say gas. Look through the sight glass at the bottom. If the pilot is out or goes out when you release the control knob, the heating system has failed.
  • Good: The pilot will not light or goes out when you release the knob—heating fault. Proceed to Check gas supply and pilot.
  • Bad: The pilot stays lit—different problem (hot water output, tank). See When to get help.

Check gas supply and pilot

Goal: Rule out gas supply and pilot orifice issues. If the pilot is out, call a plumber.

  • Confirm the gas supply valve on the line feeding the water heater is fully open (parallel to the pipe). Check that other gas appliances in the home work.
  • If the pilot will not light, shut off the gas, inspect the pilot orifice, and clear any debris with a thin wire or needle. Do not enlarge the hole.
  • Good: Gas is on and pilot orifice is clear. If the pilot is still out, call a plumber—gas pilot work requires a professional.
  • Bad: No gas at other appliances—call a pro for gas supply. Pilot out or will not stay lit—call a plumber. Do not attempt to work on the pilot yourself.

When to get help

If you smell gas, evacuate immediately. Do not turn on lights or appliances. Call 911 or your gas utility from outside. Do not call a technician for an active gas leak—that is an emergency.

Call a plumber if:

  • The pilot is out.
  • The pilot will not stay lit when you release the knob.
  • You suspect a gas leak.

Do not attempt to work on the pilot yourself. Gas pilot work requires a professional.

Verification

  • The gas supply valve is on and the pilot orifice is clear.
  • If the pilot is out or will not stay lit, you have called a plumber.
  • No gas odor. If you smell gas, evacuate and call 911 or your gas utility from outside.

Escalation ladder

Work from the device outward. Stop when the problem is fixed.

  1. Confirm symptom Verify the pilot will not light or will not stay lit; rule out a different problem.
  2. Gas supply and pilot orifice Check gas valve is on and pilot orifice is clear. If the pilot is out, call a plumber.
  3. Call a pro Gas smell—evacuate, call 911 or gas utility from outside. Pilot out or will not stay lit—call a plumber.

What to capture if you need help

Before calling support or posting for help, have these ready. It speeds everything up.

  • Whether gas supply is on
  • Whether the pilot is lit at all
  • Whether the pilot stays lit when you release the knob
  • Steps already tried

Will the pilot not light or not stay lit?

Check the label on the tank—it should say gas. Look through the sight glass at the bottom. If the pilot is out or goes out when you release the knob, the heating system has failed.

Look through the sight glass. Good: pilot will not light or goes out when you release the knob—heating fault. Bad: pilot stays lit—different problem; check hot water output or tank.

Yes No

You can change your answer later.

Is the gas supply on and the pilot orifice clear?

Gas supply valve must be fully open. Pilot orifice may be clogged. Check both.

Confirm the gas supply valve is fully open (parallel to the pipe). Check that other gas appliances work. If the pilot will not light, shut off gas, inspect the pilot orifice, and clear any debris with a thin wire. When the orifice is clear, call a plumber to restore the pilot. Good: gas on and orifice clear. Bad: no gas at other appliances—call a pro for gas supply.
Question

Is the gas supply on and the pilot orifice clear?

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You can change your answer later.

Call a plumber

If you smell gas, evacuate immediately. Do not turn on lights or appliances. Call 911 or your gas utility from outside—do not call a technician for an active gas leak. Call a plumber if: the pilot is out; the pilot will not stay lit; or you suspect a gas leak. Do not attempt to work on the pilot yourself. Never work on gas lines or gas valves yourself.

Done

Reviewed by Blackbox Atlas

Frequently asked questions

Why would a gas water heater pilot not light?
Common causes: gas supply off, pilot orifice clogged, thermocouple dirty or failed, or gas valve faulty. Check gas supply and pilot orifice first. If the pilot is out or will not stay lit, call a plumber—gas pilot work requires a professional.
Can I fix a water heater that will not light myself?
You can check the gas supply and pilot orifice. If the pilot is out or will not stay lit, call a plumber—gas pilot work requires a professional. Do not attempt to work on the pilot yourself.
When should I call a plumber for a water heater that will not light?
If you smell gas, evacuate immediately and call 911 or your gas utility from outside—do not call a technician for an active leak. Call a plumber if the pilot is out, the pilot will not stay lit, or you suspect a gas leak. Gas valve and thermocouple work require a professional.

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