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How to Recognize a leak


Natural gas and Highly Volatile Liquids (HVL) are colorless and nearly invisible to the eye. Small leaks can be identified by looking for dying or discolored vegetation in a naturally green area.

Hazardous liquids produce a strong sheen or film standing on a body of water. A HVL leak may be identified by a fog-like vapor cloud in areas of high humidity. Natural gas is colorless, but blowing dirt around a pipeline area may be observed, or vapor and “ground frosting” may be visible at high pressures, regardless of temperature.

Other ways to recognize a leak may include: water bubbling up or standing in an unusual area, a mist or vapor cloud, a powerful fire or explosion with dense smoke plumes, or an area of petroleum-stained ground.


The volume of a pipeline leak can range from a quiet hissing to a loud roar, depending on the size and nature of the leak.


An unusual smell, petroleum or gaseous odor will sometimes accompany pipeline leaks. Natural gas and HVLs are colorless, tasteless and odorless unless odorants, such as Mercaptan, are added.

Most HVLs contain a slight hydro-carbon or pungent odor. Most are non-toxic; however, products such as ammonia are considered a toxic chemical and can burn the senses when it seeks out moisture (eyes, nose or lungs). If inhaled, HVLs may cause dizziness or asphyxiation without warning.

If you suspect a pipeline leak


  • Make sure gas appliances are turned all the way OFF.
  • Leave the area.
  • Telephone 911 and the pipeline company from a safe location upwind, well away from the location of the leak.
  • If it is safe to do so, warn others against entering the leak area and/or creating ignition sparks.

Do not:

  • Start an engine of any kind.
  • Strike matches or create a flame of any kind.
  • Use a telephone or cell phone, unless from a safe location upwind, well away from the location of the leak.
  • Turn on or off any light switches, garage door openers or other electrical switches.
  • Touch, breathe or make contact with leaking product.
  • Drive into a leak or vapor cloud area.


911 and 711*

Dialing 911 is the most familiar and effective way Americans have to find help in an emergency. The Americans with Disabilities Act (ADA) requires all Public Safety Answering Points (PSAPs) to provide direct, equal access to their emergency response services for people with disabilities who use TTYs or other devices. Therefore, in the event of an emergency, TTY users should call 911 directly and not make a TRS call via 711.