Color and Odor

Natural gas is nontoxic, odorless and colorless, making it difficult to detect. Gas providers add an odorant called mercaptan to the gas in their distribution lines. It smells like sulfur or rotten eggs.

Mercaptan can be a useful indicator of a natural gas leak. However, you may not be able to smell this odorant if you’ve been exposed to it for long periods of time or if other odors mask the smell. Mercaptan also may be stripped from the gas due to chemical and physical processes, in an effect known as “odor fade.”

ALL [your utility name here] transmission pipelines have odorized gas, but it is important to note, not all gas is odorized.

So never rely on your nose alone to detect a natural gas leak. Instead, use your combustible gas indicator, (CGI), to be certain a flammable atmosphere does not exist. And be alert for other visual and auditory gas leak warning signs, including:

• A hissing, whistling or roaring sound
• Dirt being blown into the air from a hole in the ground
• Continuous bubbling in water
• A damaged connection to a gas appliance
• An exposed pipeline after an earthquake, fire, flood or other disaster
• A fire or explosion nearby
• Dead or dying vegetation in an otherwise moist area over or near a gas pipeline
• Frozen ground in warm weather