At a glance
Symptoms
- • Strong sulfur, rotten-egg, or skunk-like smell near a gas appliance
- • Hissing sound near a gas line, valve, or appliance connection
- • Pilot light has gone out and the smell remains after a few minutes
- • Dead vegetation in a line over an underground gas pipe (outdoor)
- • Faint headache, dizziness, or nausea while in the room with the appliance
- • Gas detector or carbon monoxide detector alarm sounding
- • Visible damage to a flexible gas connector or rigid gas pipe
Common causes
- • Pilot light has been blown out, leaving raw gas escaping from an older non-safety-valved appliance
- • Failed or partially open gas valve on an appliance
- • Faulty pressure regulator
- • Damaged gas line — kink, crack, or corrosion at a fitting
- • Loose connection at the appliance shutoff or supply line
- • Brief mercaptan smell after relighting a pilot or starting a recently serviced appliance (this should clear within 1-2 minutes; if it persists, treat as a real leak)
- • Cracked heat exchanger on a furnace or water heater (combustion-gas leak — also produces carbon monoxide)
Safety First — Read Before You Start
- •DO NOT operate any electrical switch — light switches, fans, garage door openers, thermostats. The small spark from a switch is enough to ignite accumulated gas.
- •DO NOT use your phone inside the home. Phones can spark internally even with no visible activity. Take the phone outside before calling.
- •DO NOT light matches, lighters, candles, or any open flame. Do not smoke.
- •DO NOT start a car in an attached garage. The starter motor is a powerful spark source.
- •DO NOT plug in or unplug any appliance — outlet sparks ignite gas just as switches do.
- •DO NOT try to find the leak yourself. Even a small soap-bubble test belongs to a licensed tech who is wearing the right equipment and has the gas supply controlled.
- •DO NOT re-enter the home until the gas company or a licensed tech has confirmed it is safe.
Tools & supplies you'll need
- No tools — this is not a DIY situation
- Phone (used from outside the home, not inside)
- Gas company emergency line phone number
- Licensed gas technician contact
Step-by-step instructions
Identify the odor and evacuate promptly
Natural gas and propane are inherently odorless. Utility companies infuse them with mercaptan, which creates that distinct sulfur or rotten-egg stench at very low levels. If you catch this scent, assume a gas leak is present regardless of intensity. The transition from a faint odor to an explosive atmosphere can occur rapidly within confined spaces. Abandon any attempt to investigate the source; your priority is to exit the building.
⚠ Warning: If you feel dizzy, lightheaded, or nauseous — leave immediately. Mercaptan does not cause those symptoms; gas accumulation does, and it means the concentration is already significant.
Ventilate only while exiting
As you move toward the exit, you may open exterior windows or doors that are directly in your path. Do not deviate from your exit route to open windows in other rooms. Avoid touching any electrical controls, including kitchen or bathroom exhaust fans, as these can trigger a spark. The goal is to facilitate airflow while you leave, not to perform a thorough ventilation of the house.
⚠ Warning: If a window is difficult to open, do not struggle with it. Prioritize your exit over ventilation. The utility company will handle the ventilation process once they arrive.
Ensure all occupants and pets are out
Gather all family members, pets, and visitors, and move to a secure location at least 50-100 feet away from the structure, such as the sidewalk or a neighbor's yard. If you reside in a multi-family unit, warn your neighbors so they can evacuate as well, as gas can migrate through shared wall cavities or attic spaces. Do not delay your departure to retrieve personal property or electronics.
⚠ Warning: Do not leave anyone behind to "investigate" or "check the kitchen one more time." A single light switch flip in a room with concentrated gas can level the home.
Notify your gas utility provider from a safe distance
Once you are at least 50 feet from your home, contact your utility provider’s emergency line. Most major providers offer 24/7 emergency response. They will guide you on whether you should attempt to shut off the gas at the meter. If you are uncertain how to do this, wait for the professionals. In Washington, you can contact Puget Sound Energy at 1-888-225-5773 or Avista in the Spokane area at 1-800-227-9187; in Oregon and Southwest Washington, reach out to NW Natural at 1-800-882-3377.
⚠ Warning: Ensure these emergency numbers are saved in your contacts, as the specific number is also listed on your monthly utility statement.
Await professional assessment outside
The utility company will send a technician equipped with specialized combustible-gas sensors to pinpoint the leak and manage the gas supply. This is a complimentary service. Remain outside until the technician verifies the environment is safe. They will determine if the leak originates from the utility infrastructure or your internal piping and appliances. Do not enter the home until they provide clearance.
⚠ Warning: Do not re-enter the home until the gas company or a licensed tech has confirmed it is safe.
Consult a licensed gas appliance technician
If the leak is traced to an appliance, the utility technician will isolate the gas supply to that specific unit and apply a warning tag. To resume service, you must hire a licensed professional—not a general handyman or an untrained individual. In the Pacific Northwest, gas work is strictly regulated by plumbing and mechanical codes. At A-Fix, we maintain the necessary licensing for residential gas appliance service and coordinate with licensed plumbers for line-related repairs.
⚠ Warning: Do not bypass a tagged appliance to keep using it. The tag is there because the appliance is unsafe at this moment.
Verify and validate the repair
Once repairs are completed, the technician will perform a pressure test and check every fitting using electronic detection equipment or leak-detection solutions to ensure the flame is burning cleanly. Do not accept any repair that has not been thoroughly pressure-tested. Ensure your carbon monoxide detectors are current and less than 7 years old. If your home lacks a CO detector on every level, install them before resuming appliance use.
⚠ Warning: A combustible-gas detector (separate from a CO detector) is a low-cost safety addition—typically $30-60—and can provide early warning for gas leaks.
Brand-specific notes
Some brands have known design quirks worth knowing about before you start.
Bosch
Bosch gas tankless water heaters and ranges have safety valves on every gas-using component, so a pilot-out-with-gas-flowing situation is unusual unless a valve has failed. Smell on a Bosch usually points to a connection at the supply rather than a control issue.
GE
GE gas appliances span a wide age range — older models (pre-2000) may not have modern flame-sensing safety valves and can leak gas if a pilot blows out. Modern GE gas ranges and dryers all have flame-sense shutoff and should not leak from a pilot loss.
Wolf
Wolf gas ranges and rangetops are commercial-style with high BTU output. The flexible gas connectors behind these heavier units are often the failure point — repeated pull-out cleaning over years can stress and crack them. Annual inspection of the connector is recommended on Wolf installations.
Viking
Viking gas appliances are similar to Wolf in being heavy commercial-style units. The convection fan and oven igniter assemblies on older Vikings can develop weak ignition that allows gas to flow briefly before lighting — if you smell a brief gas puff at oven start, schedule a service call to inspect the igniter.
Whirlpool
Whirlpool gas ranges, dryers, and water heaters all use industry-standard flame-sense and pilot ignition. A persistent gas smell from a Whirlpool is more likely a connection or regulator issue than a control issue — call a tech.
What our techs see most often
When a customer calls reporting gas smell, our dispatcher's first answer is always the same: hang up, leave the house, call the gas company. We do not roll a truck to a confirmed gas leak before the gas company has shut it off — that is not how gas safety works in Washington & Oregon. After the gas company has the leak controlled and tagged the appliance, we come out on a priority basis to repair or replace. Roughly half of the gas-smell calls we eventually service are pilot-light related on older water heaters and floor furnaces; the other half are deteriorated flexible connectors at the back of the appliance.
When to call a professional
- → You smell gas from any appliance, even faintly — call the gas company first, then a licensed gas appliance tech
- → A pilot light has gone out and you are not 100% certain about how to safely relight it (most modern appliances have automatic relight; for those that require manual relight, the procedure is on the appliance label, but if you have any doubt, call a tech)
- → You see physical damage to a gas connector — kinks, cracks, fraying, or corrosion
- → A carbon monoxide detector has alarmed (this is a separate but related emergency — leave the home, ventilate, call 911 or the gas company, and do not return until tested)
- → An appliance has been tagged or red-tagged by the gas company
- → You are renovating, moving, or replacing a gas appliance — gas line work always requires licensing
- → Any time you would otherwise be searching for a tutorial on gas line work — that is the cue to call a pro instead
Frequently asked questions
I smell gas faintly. Is it safe to keep using my appliance until I can get someone out?
No. A faint smell can mean a slow leak that is accumulating in walls, attics, or low spots in the home. The smell threshold is well below the explosive concentration but the gap can close quickly in a closed environment. Stop using the appliance, leave the home, and call the gas company. They will respond same-day for free.
Why does the smell go away after I open the windows? Was it a real leak?
Ventilation reduces the concentration but does not stop the source. If the smell came back when you closed the windows, or if it was strong at any point, it was a real leak. Even if it has cleared, have a licensed tech inspect — slow leaks at fittings can come and go with temperature and pressure cycling.
My pilot light keeps blowing out — is that the source of the smell?
Possibly. Modern gas appliances have a thermocouple or flame sensor that shuts off gas when the pilot is out, so a pilot-out should not produce a sustained gas smell. If yours does, the safety valve has failed and is allowing gas through without an active flame. That is a high-priority repair — stop using the appliance and call a tech.
Is it safe to just shut off the gas at the appliance valve and not worry about it?
Shutting off the appliance valve stops gas to that appliance, which is good. But it does not address what caused the leak in the first place — a deteriorated connector, a failed valve, a damaged regulator. Those need diagnosis and repair before the appliance is used again. The gas-off step is a holding pattern, not a fix.
How do I prevent gas leaks?
Three things. First, have all gas appliances inspected annually by a licensed tech — this catches deteriorating connectors, weak valves, and dirty burners before they fail. Second, replace flexible gas connectors every 10-15 years; older yellow-coated brass connectors are no longer code-compliant and should be replaced on sight. Third, install combustible-gas detectors and carbon monoxide detectors on each floor, replace per manufacturer schedule (CO detectors typically every 7 years).