What to Do — In Exactly This Order
Get everyone out of the building immediately
Tell everyone in the home to leave now — don't stop to collect pets, phone chargers, or belongings. Get to fresh air as quickly as possible. If someone is asleep, wake them. Natural gas accumulates in enclosed spaces and can reach explosive concentrations quickly. Speed matters more than anything else in these first moments.
Do NOT touch any switches, appliances, or outlets
Do not turn lights on or off (the switch arc can ignite gas). Do not use a phone inside the building. Do not light a match or cigarette. Do not turn on or off any appliance. The smallest electrical spark can ignite accumulated natural gas. Even a light switch or doorbell can be enough. The exception: leave doors open as you exit — ventilation is good — but don't stop to open windows.
Leave the door open as you exit but don't stop for anything
Leaving doors open as you leave promotes ventilation and doesn't create ignition risk. But don't stop or slow down to do this deliberately — if the door is already open as you exit, leave it. Exit the building, then move well away from it (minimum 100 feet). Do not stand directly outside the front door.
Call 911 and your gas company — from outside, well away from the building
Once you're at a safe distance (or at a neighbor's home), call 911. Also call your gas utility's emergency line — the 24/7 emergency number is on your bill or on their website. Gas companies have emergency technicians who respond specifically to leak calls, often faster than other services. Don't call from inside the building or from a car in the garage.
If you know where the gas shutoff is — and it's outside — turn it off
The main gas shutoff is typically at the exterior gas meter. If you can reach it without re-entering the building, you can turn it off with a wrench (quarter turn so the valve is perpendicular to the pipe = off). Do not turn off the gas if doing so requires entering or approaching the building closely. This step is optional — emergency responders will do it.
Do not re-enter until cleared by authorities
Do not go back inside for any reason until the fire department or gas company has cleared the building. This isn't negotiable, even briefly. Until the source is found and sealed, the building is not safe.
Common Sources of Gas Leaks
Gas stove or range
A burner left partially on, a poorly seated connection, or an older stove with a deteriorating seal. Check your burner knobs are fully off after cooking. If you smell gas near the stove when the burners are off, don't use the stove — call your gas company.
Gas water heater or furnace
Old or improperly maintained water heaters and furnaces can develop gas leaks. Annual inspection by a licensed HVAC technician prevents most of these. If your furnace or water heater is over 15 years old, consider replacement.
Flexible connector hoses
The flexible connectors between gas lines and appliances degrade over time. These are a leading source of residential gas leaks. Older accordion-style connectors are particularly prone to failure — modern corrugated stainless (CSST) connectors are safer.
Outdoor gas lines
Underground gas lines can be damaged by tree roots, soil shift, or DIY digging projects. If you're digging in your yard, call 811 (national US line) to have underground utilities marked before you dig. Always.
Carbon Monoxide: The Gas Leak You Can't Smell
Detector Placement: What the Codes Actually Require
- Natural gas detectors: Install near floor level (natural gas is lighter than air and rises, but propane/LP sinks — know which you have). Near the stove, water heater, and furnace are priority locations.
- CO detectors: Install at knee height or higher on each floor. Required near sleeping areas in most US states. Near garage entry doors if you have an attached garage. Test monthly.
- Combination smoke/CO detectors are available ($30–50 each). Nest Protect is the gold standard — it has voice alerts and self-tests. A combination unit near each bedroom is the minimum for most homes.
Nest Protect detects both smoke and CO — and tells you which room and what's happening
Unlike standard detectors that beep anonymously, Nest Protect gives voice alerts in plain language and tests itself automatically.
Frequently Asked Questions
I thought I smelled gas but I'm not sure. What should I do?
Treat any suspected gas smell as real until proven otherwise. Leave the building, then call your gas company's non-emergency or emergency line — they'll send someone to check. Most utilities offer this check for free. If the smell was faint and brief and you're not experiencing any symptoms, calling the non-emergency line is appropriate. If it's strong or persistent, treat it as an emergency and call 911.
My gas company turned off my gas after a leak. How long does it take to turn back on?
Your utility won't restore gas until a licensed plumber or gas technician has repaired the leak source and tested the lines. That can take anywhere from a few hours (if a simple connection was loose) to several days (if a line needs replacement or a new permit is required). Your utility will then send someone to do a final safety inspection before relighting pilots and restoring service.
Is propane different from natural gas in a leak?
Yes. Propane (LP gas) is heavier than air and sinks to the floor and into low areas — basements, crawlspaces. Natural gas is lighter than air and rises to the ceiling. Both have a distinctive added odor (mercaptan) and both create explosion risk. The evacuation procedure is the same for both: get out, don't touch anything electrical, call for help from outside. Propane detectors should be placed low; natural gas detectors placed high.