If you smell gas in the house, this is a leave-now emergency. Here is exactly what to do — and what never to do — plus how licensed gas line repair works once the property is safe.
Written bySteven Lockhart·Reviewed byMiguel Lopez, Owner & Licensed Plumber, New Pro Plumbing (CSLB #974600)·Last reviewedAugust 2026 · 8 min readIf you smell gas right now: leave the building immediately, do not touch any light switches or flames, and call 911 and your gas company from outside. Do not go back in until they say it is safe.
If You Smell Gas
Leave the building immediately and take everyone, including pets, with you. Do not switch anything on or off, use a phone, or light a flame inside. From a safe distance outside, call 911 and your gas company’s emergency line. Do not go back in until they say it is safe. This applies any time you smell gas in the house.
Natural gas is highly flammable, and a leak in an enclosed space can build to a level where a single spark — from a light switch, an appliance, or a phone — ignites it, causing a fire or explosion. Breathing it can also cause dizziness, headaches, nausea, and, at high levels, loss of consciousness. That combination of fire risk and health risk is why a suspected gas leak is treated as leave-now emergency, not something to investigate.
Because natural gas is naturally colorless and odorless, gas utilities add a chemical odorant, mercaptan, that smells strongly of rotten eggs or sulfur — deliberately, so that leaks are easy to notice. That smell is your warning. Knowing the signs of a gas leak and exactly what to do if you smell gas is the kind of safety knowledge worth having before you ever need it.
One important overlap: sewer gas from plumbing also smells like rotten eggs. If you are ever unsure which you are smelling, treat it as natural gas and follow the steps below — it is always safer to evacuate for a false alarm than to stay for a real leak.
Any one of these is reason enough to leave and call. You do not need to be certain — natural gas leak safety is built on acting on the warning, not waiting for proof.
Follow these steps in order. The goal is simple: get everyone out and away, then call for help from outside.
Get everyone out of the building — do not stop to investigate or gather belongings.
Bring all people and pets with you as you go.
No light switches, appliances, garage-door openers, or thermostats — a spark can ignite gas.
Do not light a match or lighter, smoke, or start a vehicle in an attached garage.
Move a safe distance from the building — do not linger by the door.
From outside, call 911 and your gas company’s emergency line.
Do not re-enter until 911 or the gas company tells you it is safe.
When you call, 911 and your gas company respond to make the property safe — locating the leak, shutting off the gas, and ventilating. The utility may “red-tag” the meter or a specific appliance, meaning gas stays off until the problem is repaired. This is the point at which a plumber comes in: gas line repair happens only after the leak has been made safe, never during an active leak.
Once the property is cleared, licensed gas line repair restores the system properly — repairing or replacing the failed line, pressure-testing it, and passing inspection before gas flows again. New Pro is licensed for exactly this work, and it is a core part of our emergency plumber services on the Westside. If the smell turns out to be sewer gas rather than natural gas, that is a different, non-emergency plumbing fix; and if a gas appliance simply will not stay lit, that is usually the appliance, such as a water heater pilot light, not a leak.
The division of labor matters and is worth remembering: the gas company handles the active leak and makes it safe; a licensed plumber handles the repair afterward. Trying to compress those into one DIY step is exactly what makes gas leaks dangerous. That is why our 24/7 emergency plumbing approach to gas always starts with “is it safe yet?” — and why the emergency plumbing service you call for the repair should always be licensed, permitted, and pressure-testing its work.
The Bottom Line
If you smell gas, the response is always the same and always first: leave, do not touch anything that could spark, and call 911 and your gas company from outside. Do not investigate, do not try to fix it, and do not go back in until it is safe. Repair — licensed, tested, permitted — only happens after the property has been made safe. When in doubt, treat it as a leak and get out.
Leave the building immediately, taking everyone and any pets with you, and do not stop to investigate or find the source. Do not touch light switches, appliances, or anything electrical, and do not light a flame — a single spark can ignite gas. Once you are a safe distance outside, call 911 and your gas company’s emergency line. Do not go back inside for any reason until 911 or the gas company confirms it is safe to return.
Natural gas is naturally odorless, so utilities add a chemical odorant called mercaptan that smells strongly of rotten eggs or sulfur — this is a deliberate safety measure so leaks are noticeable. If you smell that distinctive rotten-egg odor, treat it as a possible gas leak. Note that sewer gas smells similar, so if you are certain a gas leak is ruled out the smell may be plumbing-related — but when in doubt, always treat it as gas and leave.
Your priority is to leave immediately, not to ventilate. While opening a window in passing on your way out is not harmful, you should not stay inside or go around the house opening windows, because every extra moment in a building with a gas leak is a risk, and reaching for a window near an ignition source is dangerous. Get out first, then call 911 and the gas company from outside and let them handle making the property safe.
Generally, no — not unless the gas company specifically instructs you to and you can do it safely from outside. Trying to locate and operate the gas meter shut-off during a leak can put you in the hazard longer than necessary, and operating anything nearby risks a spark. The safest action is to leave and let the professionals shut off and make the property safe. Only after that is done does any repair happen, and gas line repair is always licensed work.
From a safe location outside, call 911 first, and also call your gas utility’s emergency line — the number is on your gas bill and on the utility’s website, and utilities have 24-hour emergency response for leaks. These are the people who make the property safe. A plumber does not respond to an active leak; a licensed plumber repairs the gas line only after the utility has confirmed the property is safe. If you are unsure whether it is gas or sewer gas, treat it as gas.
This safety guide was written by the New Pro Plumbing content team and reviewed by Miguel Lopez, owner and California-licensed plumber (CSLB #974600). It follows public safety guidance from PHMSA, the CPSC, and gas utilities. It is general safety information, not a substitute for calling 911 and your gas company in an emergency. New Pro performs licensed gas line repair only after the utility has made a property safe.
Last reviewed: August 2026.
Once the gas company has made your property safe, we handle the licensed, permitted, pressure-tested repair. Never during an active leak — leave and call 911 for that.
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