A strong gas smell in the house is a leave-now emergency. Do not flip any switch on or off. Get everyone outside, leave the door open behind you, and call 911 and National Grid from the street. After the utility clears the home, call All Island Comfort at 631-591-2289 to find and fix the leak.
A Strong Gas Smell: Do This Right Now
If the rotten-egg smell is strong, steady, or in more than one room, act first. You can finish reading this guide from the sidewalk.
1. Get everyone out now. Children, pets, everyone. Do not stop to hunt for the source. Do not stop to pack anything. Walking out the door is the entire plan.
2. Do not touch anything electrical. Do not flip a light switch on or off. A switch can make a tiny spark in either direction, and a spark is all a gas-filled room needs. Leave every lamp and appliance exactly as it is.
3. Do not use a phone inside. No calls, no texts, no flashlight app. Make every call from outside, well away from the house, or from a neighbor's home.
4. Stay out of the garage. Do not start a car in an attached garage. Do not press the garage door opener, because the motor can spark. If the car matters, it can sit there until the house is cleared.
5. Leave the door open behind you. An open door lets gas drift out and lets responders in. Do not stop to open windows on your way. Just go.
6. Call 911, then National Grid. From outside, call 911 first. Then call National Grid's 24-hour gas emergency line for Long Island at 1-800-490-0045. Tell both where the smell is strongest.
7. Stay out until you are told it is safe. Do not go back for a wallet, and do not go back for a pet that already got out. The fire department or the utility gives the all-clear, not your nose.
What a Gas Smell in the House Usually Means
Not every whiff is the same emergency. Here is how we read the pattern.
| Symptom | Likely cause | Urgency |
|---|---|---|
| Strong rotten-egg smell in one or more rooms | Active natural gas leak | Get out, call 911 now |
| Faint whiff near the stove that fades | Bumped burner knob, or a pilot light that went out | Check it today |
| Rotten-egg smell strongest near a basement floor drain | Sewer gas rising through a dried-out trap | Can wait a day |
| Rotten-egg smell only when hot water runs | Water heater chemistry, not a gas leak | Can wait a day |
| Gas smell outdoors near the meter | Possible leak at the meter or service line | Call National Grid now |
What to Check Yourself After a Faint Whiff
This section is only for a faint, momentary whiff that has already faded. A strong or steady smell means the steps at the top of this page, not a checklist. When in doubt, treat it as strong and leave.
1. Draw the line first (1 minute). Faint, brief, and gone means you can look around. Strong, spreading, or growing means you walk out now. Anyone in the house feeling dizzy or sick also means you walk out now.
2. Check every stove knob (1 minute). A knob bumped a hair past off releases unburned gas with no flame. It is the most common cause of a faint kitchen whiff we see. Turn every knob firmly to off, including the oven.
3. Look at the pilot lights (2 minutes). Older water heaters and gas ranges often use a standing pilot, and so do some space heaters. Look through the little window near the base for a small blue flame. If a pilot is out, gas can seep while the smell stays faint. Do not relight it yourself if you smell anything, and call us instead.
4. Pour water into the floor drains (2 minutes). A basement or laundry floor drain that has not seen water in months lets sewer gas rise into the house. Sewer gas smells like rotten eggs too. Pour a quart of water into each floor drain and see if the smell quits over the next day.
5. Air out and retest (10 minutes). Open windows on two sides of the room, then step outside for ten minutes. Come back in with a fresh nose. If the smell has returned, stop treating it as a fluke, go back outside, and call National Grid.
Call Now or Can It Wait
Leave and call 911 plus National Grid, any hour:
- A strong or steady gas smell anywhere in the house
- A faint smell that keeps coming back after the checks above
- Any hissing sound near a gas line or appliance
- Anyone in the house with headache, dizziness, or nausea
- A gas smell outside near the meter or along the service line
- A propane smell in a basement or crawl space, even a faint one
It can wait for a daytime call to us:
- A faint whiff traced to a bumped stove knob, now aired out and gone
- A rotten-egg smell that only shows up when hot water runs
- A floor-drain smell that stopped after you refilled the trap
- A pilot light that is out with no gas smell in the room
Nothing on the second list involves a live gas leak. The moment a smell comes back or gets stronger, it moves to the first list.
Why Gas Smells Like Rotten Eggs
Natural gas has no color and no smell of its own. Utilities add a chemical called mercaptan before the gas reaches your street. Mercaptan reeks of rotten eggs or sulfur at tiny concentrations, so a leak announces itself long before the gas builds to a dangerous level. That stink is a safety feature working exactly as designed.
Do not rely on your nose alone, though. The odor can fade as gas passes through soil or rusty pipe, and some people lose sensitivity to it with age, colds, or smoking. Other leak signs include a hissing sound near a line, a patch of dead grass over a buried pipe, and bubbles in standing water outside. A plug-in natural gas detector is cheap insurance, and it is not the same device as a carbon monoxide alarm.
Natural Gas, Propane, or Sewer Gas: Three Different Problems
The rotten-egg smell has three common sources on Long Island, and they behave differently. Knowing which one you have changes who you call.
Natural gas rises
Natural gas is lighter than air. It drifts up, collects near ceilings, and travels to upper floors. A smell that seems strongest upstairs or near the ceiling fits a natural gas leak. It comes from National Grid's mains and your house piping.
Propane sinks and pools
Propane is heavier than air. It flows downhill like water and pools in basements, crawl spaces, and low corners, where it can sit long after the smell fades at nose height. Plenty of East End and North Fork homes run on propane tanks instead of gas mains. If your home is one of them, the get-out steps are the same, and your call from outside goes to 911 and your propane supplier.
Sewer gas is the look-alike
Sewer gas carries hydrogen sulfide, which smells like rotten eggs on its own. It rises through dried-out drain traps, failed toilet wax rings, and cracked vent pipes. A smell that hugs one drain, in a home with no gas appliance nearby, usually points here. It is a health irritant and a plumbing problem rather than an explosion risk, but if you cannot tell the difference, treat it as gas and make the call.
The smell is outside, near the meter
An outdoor gas smell near the meter or along the path to the street still gets a call to National Grid. Leaks at meters and buried service lines are their equipment and their emergency, and they respond around the clock. Do not dig near the line for any reason, and call 811 before any digging project on the property.
Never Hunt for the Leak Yourself
The old trick of tracing a gas line with a lit match is how houses end up on the news. Natural gas burns when it makes up roughly 5 to 15 percent of the air in a room. Inside that range, one flame or spark can ignite the whole space, not just the leak point.
Soapy water on fittings is not much smarter on a live leak. It keeps you standing inside a house that may already hold an explosive mix, it only finds leaks at the exact joints you brush, and it says nothing about the hidden piping in walls and crawl spaces. Leak-hunting is safe work only after the gas is shut off, with a pressure gauge and an electronic detector. That is the utility's job first and ours second, never a homeowner's.
What We Do When We Arrive
National Grid's crew makes the house safe, and that usually means shutting the gas and locking the meter. They do not repair the piping on your side of the meter, which is where we come in. We put a gauge on the house piping and pressure-test it, which proves whether the system holds and how badly it leaks. Then we walk the lines with an electronic combustible-gas detector to pinpoint the exact fitting or pipe section at fault.
You get the repair price in writing before we open a single joint. After the repair we pressure-test again, because a gas system gets proven tight, not assumed tight. Then we work with the utility to get the meter unlocked, restore gas, and relight every appliance. You end the day with heat, hot water, and appliances you can trust.
What Finding a Gas Leak Costs
Once the utility has made the house safe, leak detection falls under our regular $189 service call. That covers the diagnosis, the pressure testing, and the first hour of labor. After-hours emergency calls are $249.
If the test finds a leak, the repair is priced in writing before any work starts. Parts are extra and quoted up front. A small fix, like a failed fitting or valve, often lands within the service call plus a part, while a major piping repair runs $500 to $950 on average.
Gas Off After a Leak?
We pressure-test, pinpoint, and repair house gas piping across Suffolk and Nassau. Our licensed gas line installation team handles everything from one bad fitting to a full re-pipe.
Call 631-591-2289Why Gas Smell Calls Are Different on Long Island
National Grid supplies the natural gas on Long Island, and their emergency crews are the first call for any leak. What they do not do is repair the piping past your meter. Two decades of oil-to-gas conversions have threaded new gas lines through pre-1960 basements in Nassau and western Suffolk that were never built for them, with long runs past old oil equipment and damp foundation walls. Those same older basements have floor drains that dry out and fake a gas smell every winter.
Geography adds two more wrinkles. Beyond the reach of the gas mains, much of the North Fork and East End runs on propane, which sinks into basements and crawl spaces instead of rising like natural gas. Near the shore, salt air eats at outdoor meters, exposed piping, and tank fittings faster than anything inland sees. We carry that map in our heads, so tell us your town and your fuel when you call.
Any gas smell, carbon monoxide alarm, or smoke means the same first move: get everyone out, then call 911 and National Grid from outside. Call us after the utility has made the house safe.