Smell Gas in House? What to Do Now
If you smell gas in your house, knowing what to do in the next few minutes matters more than figuring out where the smell is coming from. Natural gas is odorless on its own, so utilities add a chemical called mercaptan that smells like rotten eggs or sulfur. That smell is a warning system, and it means you should act right away. This guide gives you the exact steps to take, what not to do, and when it is safe to go back inside, so you can protect your household without panic or guesswork.
Act Immediately: Leave the House
The moment you notice a gas smell, especially a strong one, get everyone out of the house. That includes children, elderly family members, and pets. Do not stop to open windows, gather belongings, or investigate the source. Walk calmly to the nearest exit and leave the door open behind you if you can do so without delay, since ventilation helps, but do not spend time on it. If anyone in the household feels dizzy, nauseous, headachy, or unusually tired, treat that as a serious sign of gas exposure and get them into fresh air immediately. Move at least 100 feet from the house if possible, or to a neighbor's yard, and do a head count. If someone is unconscious or cannot move on their own, call 911 right away and only re-enter if emergency dispatchers tell you it is safe and you can do so without putting yourself at risk. Firefighters have breathing equipment and gas detectors for exactly this situation. Your safety comes before property, and there is no smell so faint that it justifies staying inside a house that may be filling with gas.
Do Not Flip Switches or Use Phones Inside
Natural gas becomes explosive when it mixes with air in the right concentration, and a tiny spark can ignite it. That is why the rules about what not to do are just as important as the rule to leave. Do not turn lights on or off. Do not flip any electrical switch, including garage door openers, fans, and appliances. Do not use a landline phone inside the house, and do not use a cell phone inside either — a phone can spark when it connects to a network or when a button is pressed. Do not light matches, candles, or cigarettes. Do not start a car in an attached garage, and do not operate any electrical equipment. Even a doorbell can spark. If you are already outside, use your cell phone there, or borrow a neighbor's phone. If you must pass through the house to leave, do not touch switches on your way out. This advice applies even if the smell seems mild. A small leak can grow, and gas can accumulate in a closed room or basement faster than you expect. For more on the shutoff hardware involved, see our guide to gas shutoff valve types and our gas lines hub.
Call 911 and Your Gas Utility From Outside
Once you are safely outside, call 911 first if the smell is strong, if anyone feels ill, or if you hear hissing or see a damaged gas line. Fire departments respond to gas calls every day and carry detectors that measure gas concentration. Then call your gas utility's emergency line, which is printed on your gas bill and usually available 24 hours a day. Tell them your address, that you smell gas, how strong the smell is, and whether anyone feels sick. Do not assume a neighbor already called. Utilities treat gas odor calls as emergencies and typically send a technician quickly, often at no charge for the emergency response itself. Stay outside and away from the house until responders arrive, and keep others, especially children, away from the building. If responders ask you to move farther back or to evacuate neighboring homes, follow their instructions immediately. Do not re-enter to grab pets, valuables, or to turn off the gas yourself unless a firefighter or utility technician explicitly tells you to do so and explains how. In many cases, responders will shut off the gas at the meter themselves.
What If the Smell Is Faint?
A faint, brief whiff of gas near a stove right after lighting a burner is often normal: a small amount of unburned gas escapes before the flame catches. If the smell disappears within a minute or two, the burner lights normally, and no one feels ill, it is usually not an emergency. But a faint smell that persists, returns repeatedly, or shows up in a room with no gas appliance deserves the same caution as a strong smell. Open no windows from inside if you can avoid lingering — instead, step outside and call your gas utility's non-emergency or emergency line for advice. Utilities would rather investigate a false alarm than miss a real leak, and they will tell you honestly whether to wait outside or to come back in. Never try to judge a leak by smell alone. Mercaptan odor can fade over time, a condition called odor fade, and some people have a reduced sense of smell. A gas detector or a professional's meter is the only reliable check. If you are ever unsure whether a smell is normal or dangerous, treat it as dangerous. The cost of a false alarm is a visit; the cost of ignoring a real leak can be a fire, an explosion, or carbon monoxide exposure.
Common Causes of a Gas Smell
Most residential gas smells come from a short list of causes. A pilot light that has gone out on a furnace, water heater, or fireplace lets unburned gas seep into the room. A loose or aging flexible connector behind a stove or dryer can develop a slow leak. A burner left on without a flame, or a stove knob bumped partway on, releases gas directly. Cracked or corroded gas piping, especially older steel lines, can leak at joints. A recently moved appliance may have stressed its connector. Outside the home, a damaged underground line, construction nearby, or a meter problem can push gas toward the house through soil or conduit. Seasonal patterns matter too: furnaces that sit idle all summer sometimes develop issues on first startup in fall, which is when many homeowners first notice a smell. Regular maintenance catches most of these problems early, which is why our gas line maintenance guide recommends an annual inspection. If a technician finds your piping is aging, see how long gas lines last to understand replacement timelines.
How Professionals Find and Fix Leaks
When firefighters or utility technicians arrive, they will use handheld combustible gas detectors to measure gas levels room by room and locate the source. They may shut off gas at the meter, ventilate the house with fans, and check appliances and connections. If the leak is on the utility's side of the meter, the utility repairs it. If it is on your side, you will need a licensed plumber or gas fitter to repair it, and the utility may leave the gas off until the repair passes inspection. Technicians often test joints with a soapy water solution, since bubbles reveal even small leaks, and they may pressure-test the whole system to confirm there are no additional leaks. Repairs can range from tightening a fitting or replacing a flexible connector, often 150 to 400 dollars, to replacing a section of pipe, which can run 500 to 2,000 dollars depending on length and access. After repairs, the technician will purge air from the lines, relight pilots, and verify each appliance burns correctly before restoring full service. Never accept a repair that skips the pressure test, and never relight pilots yourself after a leak-related shutoff unless a professional has cleared the system.
After the All-Clear: Next Steps
Once professionals confirm the house is safe and the leak is fixed, ventilate the home by opening windows for a while, especially in the room where the smell was strongest. Check on everyone in the household: headaches, dizziness, nausea, and fatigue after gas exposure should be evaluated by a doctor, even if symptoms fade in fresh air. Keep the technician's report and any repair invoices, since they document the cause and the fix for insurance or future buyers. If the leak came from an appliance, consider having that appliance serviced or replaced rather than simply relighting it and moving on. If the leak came from piping, ask the plumber whether the rest of the system should be inspected, since one failing joint can signal wider corrosion. Consider installing a natural gas detector, similar to a carbon monoxide detector, near gas appliances and in bedrooms. These detectors sound an alarm at low gas concentrations and give you warning before odor alone would. They cost 30 to 80 dollars each and are a sensible addition to any home with gas service, alongside the carbon monoxide detectors most codes already require.
Preventing Gas Smells in the Future
Prevention is straightforward and mostly comes down to routine care. Schedule a professional gas system inspection once a year, ideally before heating season. Replace flexible appliance connectors every 10 to 15 years, or sooner if they look worn, and never reuse a connector after moving an appliance. Keep the area around your gas meter clear and visible, and know where your main shutoff is. Teach everyone in the household the smell of gas — some utilities offer free scratch-and-sniff cards — and rehearse the evacuation steps the way you rehearse a fire drill. Never store flammable materials near gas appliances, and never block appliance vents. If you plan digging in your yard, call 811 before you dig so underground gas lines are marked; striking a buried line is a leading cause of serious outdoor gas incidents. Finally, save your gas utility's emergency number in your phone now, while you are calm, so you are not hunting for it during an actual emergency. A household that knows the steps reacts in seconds, and seconds are what keep a gas smell from becoming a gas disaster.
If you take one thing from this guide, let it be the order of operations: out first, no switches, call from outside, stay out until cleared. Do not try to find the leak with a flame, do not turn the gas back on yourself, and do not assume a faint smell is harmless without a professional check. Gas systems are safe when respected, and the smell added to natural gas exists precisely so that you can act early. Teach these steps to your family, keep your utility's emergency number handy, and schedule the annual inspection that catches problems before they announce themselves by smell.