Common Signs of a Natural Gas Leak

Kitchen Gas Stove Burner
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More than 65 million homes in the U.S. use natural gas or liquid propane (LP) to power furnaces, stoves, ovens, water heaters, and other appliances. Gas is one of the safest and cleanest fossil fuel, and it is also better for the environment, as it produces mostly water vapor and carbon dioxide and significantly fewer greenhouse emissions than is produced by burning oil, coal, or wood.

But natural gas is highly combustible. This means it can produce a lot of heat when you burn small amounts, but it also means that a natural gas leak can pose a serious risk of fire and explosion since it spreads quickly and goes up in flames easily. If you have a gas leak in the house, any electrical spark or fire source can ignite the gas—with results that can be devastating.

It's important for everyone in your family to be educated about gas leaks, as a leak in or around the home can be quite dangerous. Even if it doesn't ignite, a natural gas leak can, at certain levels, kill you through suffocation. In much the same manner that carbon monoxide can kill by preventing the body from absorbing oxygen, natural gas or LP gas in the air at high concentrations can have the same effect.

Indoor Signs of a Gas Leak

To help ensure that you live safely using natural gas, be aware of the signs of a gas leak. A gas leak indoors is the most dangerous, since the levels of gas in the air can quickly build up to levels that are toxic and highly explosive, so it is important to know the signs:

  • Unpleasant smell: Neither natural gas nor liquid propane has any color or odor, but utility companies include an additive that gives the gas a highly distinctive odor that almost anyone can recognize. Known as mecaptan or methanethiol, this substance is harmless but pungent-smelling; it is often described as having an odor like rotten eggs or rotting cabbage. If you can smell this odor in your home, it is likely that you have a gas leak.
  • Hissing sound: A hissing sound coming from the area around a gas appliance is often a sign of a gas leak. This is a highly dangerous situation, since it means that large quantities of gas are escaping. If you can hear a gas leak, you almost certainly will also smell it. Don't try to fix the connection yourself; leave the house and call the utility company to investigate.
  • Dead house plants. Plants are extremely sensitive to any buildup of gas in the air, and they may begin to die before you can detect any gas odor in the air. Failing house plants may indicate you have a slow gas leak that is otherwise undetectable.
  • Pet symptoms: Unusual behavior in dogs, cats, birds, and other pets can be a sign of a gas leak. If pets show lethargy, lack of appetite, vomiting, or other symptoms, make sure to check for a gas leak. Pets are often more sensitive to humans when it comes to air quality.
  • Health symptoms: Dizziness, breathing difficulties, or flu-like symptoms can sometimes be caused by the presence of gas in the air. If the symptoms can't be explained in any other way—and especially if the symptoms disappear when you are away from the house—it's wise to check for gas leaks.

Outdoor Signs

Look outside the home as well for evidence of a gas leak, including:

  • Visible air movement: A gas leak from an underground pipe can cause dirt to be thrown into the air or plants to be blown, as if by a breeze. Unusual air movement from the ground near the home is a possible sign of a gas leak.
  • Bubbles: A leak in a gas pipe can sometimes cause bubbling in moist ground areas around the home. A water puddle that bubbles may be hiding a leaking underground gas pipe.
  • Dying plants: Plant life near a gas leak will become sickly and eventually die. While plants can certainly wilt and die due to a variety of reasons, plants that die without an obvious cause can indicate a gas leak. A natural gas leak blocks a flower's source of oxygen and fruits and vegetables will change color when they come in contact with natural gas. If you see dead or discolored plants surrounded by healthy green plants, it is worth investigating.
  • Dry spot inside an area of moist ground. A gas leak can dry out moist ground, so if you see an unusual spot of dry earth within a moist area, it may mean that leaking gas from an underground pipe is drying out the soil.
  • Ground on fire. A clearly defined blue or yellow flame coming from the ground, or a flame appearing to hover above the ground, is a clear sign of a gas leak in an underground pipe. Move far away from the area and call the authorities immediately.

How to Stay Safe

If you suspect a gas leak in or around your home, stay calm, stop what you're doing (don't turn any electrical switches on or off or unplug anything) and go outside immediately. Inhaling high concentrations of natural gas can lead to asphyxia—a potentially fatal condition in which your body is deprived of oxygen, and you may not recognize it until it is too late. Once you're at a safe distance from the house, call your gas company to come and inspect for leaks. Utility technicians have special tools that can detect even minute amounts of gas in the air.

Just because you don't detect the familiar rotten-egg smell, doesn't mean you may not be in danger. There still may be small quantities of gas that are affecting you and your family, so it is better to be safe than sorry.