Gas leaks are much more common than you may think

Gas leaks are much more common than you may think

One of the most intriguing and surprising things I have noticed as a home inspector is that we find so many gas leaks in our work. It’s amazing, shocking, and it’s not good. Gas leaks are potentially extremely dangerous, and unhealthy, and they are a tremendous waste of resources. Even as I write this, the gas utility has been working on my street for the past two days to repair a leak on piping running to my neighbor's house here in Watertown.

We find gas leaks often. It never fails - at least once a month on an inspection, I will notice that characteristic odor of Mercaptan, the odoroant added to natural gas to make sure that it is noticed. It smells like nothing else, and it’s so distinctive that it can be identified even in extremely small quantities. Sometimes it is such a faint smell that you just think you smell it. But that’s what it is designed to do - the best way to think about it is: if you think you smell gas, you usually do smell gas. Next step: call the gas utility right away.

Gas leak located in a natural gas pipe coming into a home in Salem. Utility was digging up the street within an hour of reporting this leak.

Who do you call in Massachusetts? 

Eversource or National Grid are the largest providers, but there are several others, including municipal providers, depending on your area. If you know your provider, you should call them, but if you don’t know who your provider is, you can call 911 or Eversource at 800-525-8222. also has a page on the state website indicating what to do:

What causes gas leaks? 

-workmanship issues (improper pipefitting)

-freezing pipes

-corrosion/rusting pipes

-work on other parts of the gas piping system can lead to damage or leaks in places

-mechanical damage (stuff falling on, leaning on, hanging from piping)

-soil conditions (settlement of soil that piping is laid in, or other issues)

-pressure issues in piping

-other conditions

How do you find a gas leak?

You can find a gas leak with your nose - generally, the odor becomes stronger and more intense when you get nearer to the source of leakage. But once you have established that there is an odor, professionals need to step in and use more sophisticated equipment to locate the source. These are devices that detect small quantities of gas and can locate the exact place where the leakage is occurring.

Serious, large, gas leak coming into the basement from the street.

What problems do gas leaks cause?

Fire or Explosion 

Natural gas is flammable. It can accumulate inside a home, and can be ignited by a switch, outlet, spark, match, stove, or any other source of flame or spark. So it is extremely dangerous if contained within a home, then ignited by a source of ignition. That's why you should not turn on or off any appliances, and leave the home, if you suspect a gas leak.

We had a pipe freeze years ago on our street and a huge amount of natural gas was flowing into our home. It's scary to think how easily that gas could accumulate in our home.


“Methane is a component of natural gas, mainly used as a fuel source and chemical feedstock in industries. It is usually harmless, however, at high concentrations, it may reduce the oxygen percentage in air, causing suffocation.” NIH:,percentage%20in%20air%2C%20causing%20suffocation.

Extreme exposure to methane gas in high quantities and high concentration is not good for your health. This is another reason why you should leave a home if you smell gas.


Methane can cause damage to vegetation. Recent studies have linked deaths of urban trees to methane exposure. This is a huge issue because we need and value the green canopies in the urban environments we currently have for a number of important reasons, and the vast infrastructure underground on city streets can result in more and more death to this much-needed vegetation.

Just a month ago, while out walking my dog in the evening, I could smell that characteristic smell outside, on the sidewalk. I called the gas company and they were out and digging up the sidewalk to repair the leak. Imagine if that went on for decades, or if it reached high enough concentration to flow into the home... Not good for overall environmental health.


“As methane is emitted into the air, it reacts in several hazardous ways. For one, methane primarily leaves the atmosphere through oxidization, forming water vapor and carbon dioxide. So, not only does methane contribute to global warming directly but also, indirectly through the release of carbon dioxide.”,the%20release%20of%20carbon%20dioxide.

While we are not experts in gas and the gas pipeline system, our area of expertise is in inspecting the systems in a house. The aging state infrastructure is resulting in significant problems. 

Here are just a few examples of gas leaks we’ve found:

  • Gas entering in the foundation wall from underground through a small hole (frozen/cracked piping)
  • Gas entering around a gas pipe at the entrance
  • Gas entering through the front of the house through an abandoned pipe
  • Many times found at gas piping connections (most common)
  • Extreme odor observed outside between buildings
  • Gas leak in a pipe fitting connection after service professional (plumber) worked on another pipe in the home
  • Gas leak at a pipe connection for a gas fireplace

Dangerous conditions:

Gas leaks have led to fires, explosions, and other safety hazards. Numerous documented fires and explosions are caused by damaged, cracked, and leaking pipes. This is concerning, especially given the age of the infrastructure in old cities like Boston and its surrounding towns. 

Other kinds of explosions have occurred due to changes in pressure by the gas infrastructure system - like the fires and explosions in Andover in 2018 - but it is not clear, or at least we haven’t done the investigation, whether or not leaks had anything to do with the explosions in this case. If there were leaks in piping in any of these homes, it certainly could not have helped things.

It is kind of amazing when you think about it - and a huge amount of gas must be wasted due to leakage. An interesting utilization of google street view mapping cars in 2017 captured leaks in several cities in the country.

We need more of this. There is much news being generated about the move away from fossil fuels - which may ultimately be a good idea if we can create sustainable sources of energy - however in the meantime, let’s prevent waste leakage and dangerous, unhealthy conditions in the meantime. Let’s preserve our infrastructure so we don’t throw the baby out with the bathwater.  

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