How to Detect Leaking Gas

Detecting a gas leak quickly is essential for your safety. Gas leaks are dangerous because they can lead to fire, explosion, or, in some cases, exposure to harmful substances like carbon monoxide. The most common type of gas used in UK homes is natural gas, which is made up mostly of methane. It’s odourless in its natural state, but suppliers add a chemical called mercaptan to give it a strong, distinctive smell — often described as similar to rotten eggs. This is the first and most noticeable sign that gas may be leaking in or around your property.

If you detect even a faint smell of gas indoors, it's important not to ignore it. Prompt action could prevent a serious incident.

Smell Is the Most Common Warning Sign

In most cases, your nose will alert you to a leak before anything else. The rotten egg smell is intentionally added to natural gas to make it easy to detect. You might notice it more strongly near your gas cooker, boiler, fire, or meter — especially if a connection is loose, a pipe is corroded, or a flame has gone out and the gas is still flowing. If the smell becomes stronger when you’re near a specific appliance or pipe, that’s often where the leak is located.

You should never rely solely on your sense of smell, though. In some cases, the odour can be masked by other household scents, or your sense of smell may be weakened due to illness or age. That’s why additional indicators are important.

Other Signs of a Gas Leak

Beyond the smell, there are other signs that may point to a gas leak. A hissing or whistling sound near a pipe or appliance may indicate that gas is escaping under pressure. If the sound is persistent and doesn’t stop when the appliance is turned off, this suggests a leak at the connection point or valve.

You might also notice physical symptoms such as dizziness, headaches, nausea, or difficulty breathing — especially in enclosed spaces. These symptoms can result from prolonged exposure to gas and may be confused with other health issues if the leak is small or slow. Pets may also behave unusually or seem lethargic in areas where gas is leaking.

Another potential sign is unusually high gas usage. If your bills are rising without explanation or you’ve noticed your meter ticking over rapidly even when appliances are off, this could indicate a slow leak somewhere in the system.

How to Confirm a Gas Leak

If you suspect a leak, do not try to fix it yourself. However, one safe way to check for a leak around a pipe or fitting is to apply a soapy water solution to the area using a cloth or sponge. If bubbles form and continue to grow, gas may be escaping. This is a basic check used to identify external leaks on visible pipework — it should never be done near a flame, and you should not attempt it if the leak is strong or the smell of gas is overwhelming.

For a more reliable and permanent solution, you can install a gas leak detector, which continuously monitors the air for the presence of combustible gases. These are especially useful in kitchens, utility rooms, and boiler cupboards where leaks might not be immediately obvious.

What to Do If You Detect a Leak

If you believe there’s a gas leak in your home, open all windows and doors to ventilate the space. Do not use electrical switches, lighters, or naked flames, and do not smoke. If it’s safe to do so, turn off the gas supply at the mains — usually located near the meter. Once the immediate area is safe, leave the property and call the National Gas Emergency Service on 0800 111 999.

Never attempt to find or repair a leak yourself. Gas systems must only be worked on by a Gas Safe registered engineer, who will have the tools and training to locate and fix the issue safely.

Detecting Leaks from Bottled Gas or LPG

If your home uses bottled gas or LPG instead of mains gas, the signs of a leak are similar — but the risks can be greater due to the way LPG behaves. Unlike natural gas, which rises and disperses, LPG is heavier than air. This means it can collect in low areas such as cellars, kitchen cupboards, or beneath floorboards, where it may go undetected without proper ventilation.

In these environments, the rotten egg smell will still be present, but the gas may linger longer and become more concentrated. This increases the risk of ignition, especially near open flames or electrical switches. If you use LPG cylinders or tanks, regularly check the hose connections and valves for signs of wear, and make sure cylinders are stored and used in line with current safety standards.

Regular Maintenance Helps Prevent Leaks

One of the best ways to detect and prevent gas leaks is through regular maintenance. Gas appliances such as boilers, cookers, and fires should be serviced annually by a Gas Safe registered engineer. During a service, the engineer will check seals, test pipework, and inspect joints to make sure everything is airtight and compliant with regulations.

Many leaks begin with a small failure in a valve, hose, or connection. Left unchecked, these minor issues can develop into serious problems. Annual servicing not only improves performance but also gives you a chance to address potential faults before they lead to gas leaks or other safety concerns.

Carbon Monoxide Is Not the Same as a Gas Leak

It’s important to distinguish between a gas leak and a carbon monoxide incident. While both involve gas appliances, they are different hazards and require different types of detection. A gas leak involves the unburnt fuel — methane or LPG — escaping from a pipe, joint, or appliance. Carbon monoxide, on the other hand, is a toxic by-product of incomplete combustion inside a gas appliance.

This means that a gas leak detector will not alert you to carbon monoxide, and a carbon monoxide alarm will not detect raw gas. For complete protection, homes with gas appliances should have both types of detectors installed and tested regularly.

Silent and Slow Leaks Are Easy to Miss

Not all gas leaks are dramatic or obvious. Some are slow and silent, releasing only small amounts of gas over time. These types of leaks might not trigger an immediate smell but can still lead to health problems or pose a fire risk. This is especially true in older homes with aging pipework or properties where gas appliances are rarely used or located in hard-to-reach places.

That’s why it’s a good idea to occasionally check around appliances, meter boxes, and pipe runs — even if you haven’t noticed anything unusual. Installing a plug-in gas detector or having your system checked as part of your annual boiler service can help catch these issues early before they become hazardous

Final Word

Knowing how to detect leaking gas can protect your home and your life. Whether it’s a strong smell, an unusual sound, or a sudden health symptom, taking action at the first sign of a gas leak is essential. Always treat any suspicion seriously, ventilate the area, and call for professional help. Having the right alarms, maintaining your appliances, and arranging regular safety checks are the best ways to reduce the risk and catch problems early.