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What Does a Gas Leak Smell Like?

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Author Image Written by Brenda Woods Updated 03/22/2024

Natural gas provides heat to many homes across the country, powering gas appliances and systems such as the stove and water heater. While it is safe when contained within those appliances, a natural gas leak is highly dangerous and can cause a fire or explosion. Since natural gas is odorless and tasteless, a harmless substance called mercaptan is added to make the gas smell like sulfur or rotten eggs. In addition to the smell, there are other signs of a natural gas leak. We’ll identify those signs and tell you what to do if you spot them.

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Identifying a Natural Gas Leak

Although natural gas isn’t toxic, a leak increases the risk of fire or combustion, making it important to identify the gas and find the source so that you can take the appropriate safety measures.

Rotten Egg Smell

Mercaptan or thiol is an additive in natural gas that produces an odor similar to rotten eggs. The specific scent may differ slightly by region, since it’s added by the utility company, so you can visit the company’s website for more information. If you smell this odor in the home, you could have a natural gas leak.

Continuous Bubbling in Standing Water

If standing water outside your home is bubbling, there could be a leak in your outdoor gas line. This is the effect of water dissolving the leaking natural gas, resulting in visible bubbles.

Roaring or Hissing Sound

Natural gas can softly hiss or roar as it escapes from a leaking pipe. Usually, the source of the leak is the natural gas connection at the back of an appliance, in which case you’ll most likely be able to smell the gas as well.

Dead Plants

If there’s a leak in the outside gas line leading to your home, dead or dying plants could signal an issue. When natural gas leaks into your lawn, it displaces the oxygen necessary for the plant’s roots to survive. If you notice dead plants in your yard despite proper gardening care, you could have a natural gas leak. The same could be true for your houseplants if you have a slow indoor leak.

Unnatural Dirt and Air Movement

The pressure released by a leak in your natural gas line can cause an unusual amount of air to blow across your yard. If there isn’t a noticeable natural breeze and you see dirt blowing out of your yard or air blowing across plants, you could have a natural gas leak. Sometimes an outdoor gas line rupture can even cause a white mist or fog.

Health Effects

Prolonged exposure to a natural gas leak can cause health problems. Additionally, recent studies have shown that residential natural gas in some regions contains air pollutants that cause long-term health problems. More research is currently being conducted to determine the size and nature of this risk.

In the short term, as natural gas continuously leaks into your home, it can affect your sense of smell and displace oxygen, causing breathing difficulties, headaches, and nausea. If you’re experiencing these symptoms and aren’t suffering from a separate illness or underlying condition, there’s a possibility you have a gas leak.

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What to Do If You Smell Natural Gas

If you think you’re experiencing a gas leak, follow these steps:
Exit the area immediately—If the smell of natural gas is mild, open the windows of your home, turn off any open flames, and leave the house and surrounding area. If there’s a severe gas leak causing an overpowering smell or symptoms like nausea and headaches, exit your home and leave the area immediately.
Call the gas company and emergency services—Once you and any other building residents are safely away from your home and yard, contact the proper authorities to confirm and fix the leak. Contact your local natural gas supplier or call 911.
Never use your phone or other electronics near a suspected leak—If you suspect a gas leak in your home, wait until you’re outside at a safe distance from your home to use your phone to call your gas service or 911. Electronics create static electricity that’s capable of igniting the highly flammable natural gas in the air.

Read MoreStaying Safe with Natural Gas

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How to Prevent Natural Gas Leaks

Although you can’t always stop a natural gas leak, there are some precautions you can take to minimize your risk.

  • Regularly service your systems and appliances, checking them for wear and tear that can lead to a gas leak.
  • Have your appliances and pipelines professionally inspected at least once a year to confirm there are no leaks.
  • Learn where the main shut-off valve for your home’s natural gas supply is located. It’s usually outdoors.
  • Make sure your family members know what to do if they smell gas.
  • If necessary, contact a professional to have your gas fittings and shut-off valves replaced. This will prevent the old infrastructure from corroding and causing a leak.

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FAQ About Gas Leaks

What does a gas leak smell like in your house?

A substance known as mercaptan is added to your natural gas to give it a pungent rotten egg smell. If you notice this odor in your home, it’s possible you have a natural gas leak.

Who pays for a gas leak?

You as the homeowner are responsible for paying for the repair and damage caused by leaks in gas lines. Thankfully, some home warranty companies, such as American Home Shield, cover leaks and breaks in gas lines.

What should you do if you smell gas?

If you suspect a natural gas leak, open the doors and windows, turn off any open flams, exit your home, and contact 911 or your gas provider. For more severe leaks, leave the property immediately before contacting the appropriate authorities.

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