Natural gas has no smell of its own. Utilities add a chemical called mercaptan so leaks announce themselves with that sulfur, rotten-egg stink — and the additive is deliberately hard to ignore, because the correct response is not to investigate. It's to leave. Here's the sequence, in order.
Get everyone out. Say it plainly, grab the kids and the dog, and walk out. Don't stop for coats, chargers, or to crack a window. If someone is asleep, wake them and go. Speed matters more than thoroughness.
Call from outside. Once you're clear of the house — sidewalk, yard, a neighbor's porch — call 911 or your gas company's emergency line. Either one works; dispatchers coordinate with each other. This call costs nothing and neither does the visit that follows.
Stay clear and keep others clear. Wait across the street or at a neighbor's. Don't start a car parked next to the house, and wave off anyone heading toward your door. If you can smell it strongly out on the sidewalk, mention that when you call — it helps them gauge the size of the leak.
Let the responders work, and stay out until they say so. The utility crew will check the meter, the appliances, and the lines with proper detectors, and shut the gas off at the meter if needed. If you couldn't get a pet out, tell them — firefighters retrieve animals from gas-filled houses routinely. Nobody goes back in for a cat. People go back in when the crew clears the house.
A weak odor near one appliance tempts people to sniff around, light the burner to test it, or decide to see how it smells tomorrow. Don't. A faint smell can mean a small leak, and it can also mean your nose has already adapted to a stronger one — smell is a terrible measuring instrument. Utilities handle these calls constantly and would rather check a hundred false alarms than one real leak late. The gray area doesn't change the move: step out, call, let the detector decide.
Three smells get confused, and telling them apart matters — after you're safe.
Sewer gas from a dried-out drain trap smells like a swamp and stays in one bathroom or near one rarely used drain. The fix is embarrassingly simple: pour a quart of water down the drain to refill the trap.
Sulfur bacteria in the water heater make hot water itself smell like rotten eggs — the smell comes out of the tap, strongest on the hot side, and the room air smells fine. That's a water quality nuisance, covered in our guide to why hot water smells like rotten eggs, not an emergency.
A gas leak smells in the air itself — near the meter, the furnace, the stove, or everywhere — whether or not any water is running. If you can't pin the smell to a drain or to hot water use, treat it as a leak. Every time.
One related device note: carbon monoxide is the other invisible gas threat in a home, and unlike natural gas it has no odor at all — your nose can't do that job. Working CO detectors on every level, placed per our CO detector placement guide, are the only warning you get. And while you're thinking about fire and gas readiness, an extinguisher you can't reach is useless — the placement rules in our fire extinguisher guide take five minutes to apply.
Hunting for the leak. Following your nose with a phone flashlight is how a manageable leak becomes a news story. Locating leaks is what the utility's detectors are for.
Airing the house out first. Opening every window before calling feels productive and accomplishes two things: it delays your exit and puts your hands on switches and latches the whole way through the house. Ventilation happens later, by the crew, safely.
Calling from the kitchen. The phone isn't special — any electrical device used inside is a potential spark. Walk out, then dial. The call takes the same ninety seconds from the sidewalk.
Re-entering "just for a second." For medication, a pet, a wallet — the list of reasons people give is long, and the rule exists because of it. Tell the crew what you need; retrieving things is part of their job.
Smell gas: out first, call second, investigate never. The utility's emergency visit is free, fast, and judgment-free, and it's the only instrument in this story that can actually measure anything. When the smell turns out to be a dry drain trap, you've lost ten minutes. When it's real, those ten minutes were the whole game.
Either. 911 dispatchers will route it, and the gas utility's emergency line sends its own crew; they coordinate. Call whichever number you can get to first, from outside the house. If anyone feels dizzy, nauseous, or has a headache, call 911 and say so — that adds a medical response.
Rotten eggs, sulfur, or garlic — that's mercaptan, an additive, because natural gas itself is odorless. Some people notice it as a chemical or skunk-like smell instead. If a strong unfamiliar odor like that is in the air near appliances or the meter, don't spend long classifying it. Leave and call.
No — leave first, untouched house behind you. Opening windows delays your exit and means operating latches and moving through the smelliest rooms. Your phone comes with you if it's in your pocket; if it isn't, use a neighbor's. Call from outside either way.
No. Emergency leak investigations are free — utilities would rather check false alarms all day than have customers hesitate to call. If they find a leak on their side of the meter, they repair it; leaks on your side may be shut off and left for your plumber, but the check itself costs nothing.
That tells you nothing either way. CO alarms detect carbon monoxide, not natural gas — different gas, different sensor. A quiet CO alarm during a gas smell is expected, not reassuring. Get out and call.