What Does a Gas Leak Smell Like? Get Out, Fix From $120

Do this now if you smell gas

1. Leave the building on foot, and take everyone with you. Do not try to find the leak (Kansas Corporation Commission).
2. Do not flip light switches, unplug anything, ring doorbells or use a phone inside. A spark can ignite the gas (City of Mesa; California Public Utilities Commission).
3. No flames. Do not smoke or use matches or lighters (City of Mesa).
4. Do not turn appliance or gas valves and do not start a car in the garage (KCC; CPUC).
5. Once you are a safe distance away, call the gas utility's emergency line or 911 (KCC; CPUC).
6. Stay out until a gas company employee says it is safe to go back in (KCC; Peoples Gas).

What does a gas leak smell like

A gas leak smells like rotten eggs. Natural gas has no color or smell of its own, so an odorant is added to help you notice it, the City of Mesa's gas utility says, and the Kansas Corporation Commission names mercaptan as the chemical that gives the rotten egg smell. Federal rules (49 CFR 192.625) require gas in a distribution line to be readily detectable by a person with a normal sense of smell at one-fifth of the lower explosive limit, well before it can burn.

If you notice any of these, leave first and call from a safe place.

Natural gas smell vs. sewer gas, propane and carbon monoxide

Natural gas, propane and sewer gas can all smell like rotten eggs, and carbon monoxide has no smell at all. Treat each one this way:

• Propane (a tank outside the house): call your propane retailer, 911 or the fire department (Propane Education and Research Council).
• Sewer gas from a dry drain trap or cracked waste line: the Virginia Department of Health says a strong rotten egg odor means go outside and call the fire department. Once it is cleared, drain cleaning or sewer line repair fixes the cause.
• Carbon monoxide cannot be seen or smelled. Only an alarm finds it. See what to do if your carbon monoxide alarm goes off.

If you cannot smell well, the City of Mesa says a methane detector can warn you when gas is in the air.

Is it an emergency? Treat any gas smell as one

Yes. The Kansas Corporation Commission, the California Public Utilities Commission and the City of Mesa all say to leave first and call from a safe place, and KCC says to leave immediately rather than wait. A hissing sound, blowing dirt or bubbling water outside are leak signs too, by the same sources.

Who to call for a gas leak

Call the gas utility's emergency number or 911 from outside; for propane, call the propane retailer, 911 or the fire department. A plumber comes after that. Atmos Energy says the customer owns the gas piping from the meter to the house, and "a licensed plumber or qualified contractor can locate, inspect, and repair" it. CenterPoint Energy says buried piping past the meter is the property owner's to maintain and can corrode and leak. Before anyone digs, call 811 so utility lines are marked (CPUC; Atmos).

Gas leak repair cost

HomeAdvisor's June 2026 guide puts a leak at a fitting behind a stove at $120 to $250 and a leak hidden in a wall or crawl space at $270 to $760; the price depends on where the leak is.

Prices are for repairs on your side of the meter, after the utility has made the house safe.

A loose fitting behind a stove is the cheap end. A buried line is the expensive end because of digging, and Fixr says a leaking line should be replaced. Full pricing for new lines and appliance hookups is on gas line repair.

What happens before the gas comes back on

Nearly all gas line installations need a permit, HomeGuide says, and a city can require a pressure test before service returns. In Dallas, for example, the city requires a gas test at 3 psig for 15 minutes witnessed by a city inspector, who then releases service to Atmos to reconnect. Rules vary by city.

• Ask for the license number and proof of insurance. HomeGuide says licensed plumbers usually handle gas lines and some states license gas fitters separately; check the license yourself.
• Ask what the quote includes: permit, pressure test ($75 to $150 at HomeGuide) and relighting appliances.
• Ask if the appliance itself is the problem. A leak at a water heater or furnace may lead to water heater repair or furnace repair.

After-hours plumbing rates are on emergency plumber, and more plumbing jobs are on the plumbing hub. Compare prices across trades on home repair costs.

Calls go to an independent company that serves your area and takes this kind of job. Ask for its license number and proof of insurance before work starts. Some companies take emergency calls; hours vary. How calls work.

Rotten egg, sewer gas or burning smell and not sure which: gas smell in house.