Natural gas leaks are rare but can occur in a variety of places, so it is important to be aware of the signs.
Because natural gas is colorless and odorless, Unitil adds a harmless, non-toxic chemical that makes it easier to detect a gas leak before it can create a hazardous situation. The chemical additive is called Mercaptan, and it gives the rotten eggs smell to natural gas. If you aren't familiar with it, we can provide a "scratch-n-sniff" card that provides you with a sample of the odor by calling our Customer Service center at 1-888-301-7700. Natural gas is also lighter than air, so if it escapes, it rises into the air and dissipates quickly.
Signs of a Leak
Sight

- Dirt being blown or appearing to be thrown in the air
- Water bubbling or being blown into the air at a pond, creek, river or other wet area
- Fire coming from the ground or appearing to burn above the ground
- Dead or dying vegetation on or near a pipeline right of way in an otherwise green area
- Dry or frozen spot on the right of way
Sound

Hissing, blowing or roaring sound.
Smell

Rotten egg odor of Mercaptan.