Gas Leak Detection South London

Gas Safe registered gas leak detection, tightness testing, and repair across South London and Surrey.

If you can smell gas right now, leave the property immediately. Do not switch anything on or off, do not use a doorbell, light a match, or use your phone inside the building — any spark can ignite escaping gas. Once you're outside and at a safe distance, call the National Grid Gas Emergency Service on 0800 111 999. They will attend, make the property safe, and turn off the supply if needed. This is a free, 24-hour emergency service and it always comes first when gas is actively escaping.

Gas leaks are a safety issue first, a repair job second

A gas leak means natural gas escaping from a pipe, joint, or appliance connection instead of being burned safely — it's a genuine hazard, since gas is flammable and can lead to an explosion, and an appliance that isn't venting properly can also bring carbon monoxide into the property alongside it. R.W. Miller provides gas leak detection, tightness testing, and repair across South London and Surrey, for situations that fall outside an active emergency.

What R.W. Miller does

Gas Tightness Testing

Pipework, joints, and appliance connections checked with electronic detection equipment to find the exact source of a suspected slow leak.

Follow-Up Inspection

Once National Grid has attended an active leak and made the property safe, Reion carries out a full follow-up inspection and repair.

Appliance Leak Diagnosis

Boilers, hobs, and other gas appliances checked for faulty connections, worn seals, or incomplete combustion.

Pipe Repair & Replacement

Once a leak is located, the affected section is repaired or replaced, with a fixed price agreed before work starts.

The £80 first-hour diagnostic fee covers the investigation using electronic detection equipment. Once the leak is found, any repair or pipe replacement is agreed as a fixed price before further work starts — no surprises once the job is underway.

This covers follow-up inspection after National Grid has dealt with an emergency, investigation of a faint or occasional gas smell that doesn't warrant an emergency call-out, appliance-related leak diagnosis, and gas pipe repair or replacement once a leak has been located. It is not a substitute for the emergency line during an active gas escape. That call goes to National Grid first, every time.

Signs of a gas leak to watch for

Smell of gas or rotten eggs Natural gas is naturally odourless, so an odorant is added that smells like rotten eggs or sulphur. This is deliberate, so the smell is noticeable well before gas concentration becomes dangerous. If you notice it, treat it seriously.
Hissing or whistling near a pipe or meter A hissing or whistling sound close to a gas pipe, the meter, or an appliance connection point can indicate gas escaping under pressure, even if you can't smell it strongly yet.
Dead or discoloured plants near the meter or gas run Gas escaping into soil displaces oxygen from the root zone, so houseplants or garden plants near an underground gas pipe or meter box can wilt, yellow, or die for no obvious reason.
Yellow or orange flame instead of blue A boiler or hob burner should show a steady blue flame. A yellow, orange, or flickering flame suggests incomplete combustion, which can point to a gas or ventilation problem and is worth having checked.
Soot or scorch marks on or around an appliance Dark staining, soot, or scorch marks on a gas appliance or the wall behind it are a sign of incomplete combustion and should be treated as a fault, not just a cleaning job.
Feeling drowsy, nauseous, or headachey indoors These symptoms, especially if they ease when you leave the property and return when you're back inside, can point to carbon monoxide rather than a raw gas smell. Carbon monoxide has no smell at all, so physical symptoms are often the only warning.
An unusually high gas bill with no change in use If your gas bill has risen sharply without any change in how much you're using the boiler or cooker, gas may be escaping somewhere in the pipework before it even reaches an appliance.

What happens when you call about a suspected gas leak

01

Safety triage over the phone

Every enquiry starts with a phone assessment. If there's an active or strong smell of gas, you'll be told to leave the property and call the National Grid Gas Emergency Service on 0800 111 999 immediately, before anything is booked in. Nothing is scheduled while a property may be unsafe.

02

On-site detection and tightness testing

Once the property is confirmed safe to enter, whether that's a suspected slow leak or a follow-up after National Grid has attended, Reion carries out electronic gas detection and tightness testing across pipework, joints, and appliance connections to find the source.

03

Trace the source, agree a fixed price

The £80 first-hour diagnostic fee covers locating the leak. Once it's found, the repair or pipe replacement needed is explained and a fixed price is agreed before any further work starts, no surprises once the job is underway.

04

Reinstate supply and confirm the fix

After the repair, the gas supply is reinstated and retested to confirm it's holding correctly. Relevant paperwork is issued or updated, including a gas safety certificate where the property needs one.

Frequently asked questions

What should I do if I smell gas in my home right now?
Leave the property straight away. Don't switch any lights, appliances, or electrics on or off, don't use a lighter, doorbell, or your phone while inside, and don't strike a match. Once you're outside at a safe distance, call the National Grid Gas Emergency Service on 0800 111 999. They'll attend and make the property safe. Only once that's done does it become a job for a Gas Safe engineer to investigate further.
Is it safe to stay in the property while a suspected leak is investigated?
It depends entirely on what you're dealing with. If there's an active or strong smell of gas, no, leave immediately and call 0800 111 999. If it's a faint or occasional smell, unexplained high gas bills, or a concern about pipework rather than an obvious ongoing leak, that's a suspected minor issue and can usually be assessed safely with a phone call first to establish what's going on before anyone attends.
Who do I call in a gas emergency, National Grid or a plumber?
National Grid, always, for an active leak. Their Gas Emergency Service on 0800 111 999 is the first call, it's free, available 24 hours, and they have the authority to isolate the supply and make a property safe. R.W. Miller's role is the follow-up, tightness testing, inspection once the property has been made safe, and repairing or replacing the pipework or appliance connection that caused the problem, not responding to a live gas escape in place of the emergency line.
What does a gas leak smell like?
Natural gas itself has no smell, so suppliers add a chemical called mercaptan that gives it a distinctive rotten egg or sulphur smell. It's added specifically so leaks are noticeable at very low, safe concentrations, well before there's any danger. If you notice that smell anywhere in or around your property, treat it as a leak until proven otherwise.
What are the first signs of a gas leak?
The most obvious sign is the rotten egg smell described above. Other early signs include a hissing sound near a pipe, meter, or appliance connection, a boiler or hob flame burning yellow or orange instead of blue, dead or discoloured plants near an underground gas run, and an unexplained rise in your gas bill. Any one of these on its own is worth a call to get checked.
What are the symptoms of carbon monoxide poisoning?
Carbon monoxide has no smell, colour, or taste, which is what makes it dangerous. Symptoms include headaches, dizziness, nausea, breathlessness, tiredness, and confusion, often described as feeling like a bad flu without a temperature. A telltale sign is symptoms easing when you leave the property and returning when you go back inside. If you suspect carbon monoxide, get fresh air immediately and seek medical advice, then have your appliances checked by a Gas Safe engineer.
Is a gas leak call-out free, and how much does gas leak detection cost?
For an active emergency, National Grid's response on 0800 111 999 is free. For a suspected slow leak, tightness testing, or follow-up inspection, R.W. Miller charges £80 for the first hour, which covers a thorough investigation using electronic detection equipment to locate the source. Once the leak is found, any repair or pipe replacement is quoted as a fixed price and agreed with you before further work starts.
Are landlords responsible for gas leak repairs, and does this affect my gas safety certificate?
Yes. Landlords have a legal duty to keep gas pipework and appliances safe and properly maintained, and a leak found during an inspection needs to be repaired before a gas safety certificate can be issued or renewed. If a tightness test or leak investigation on a rental property turns up an issue, it's usually sensible to deal with the repair and the annual gas safety certificate in the same visit.
Gas Leak Detection across South London
Wandsworth Lewisham Greenwich Lambeth Clapham Southwark Bromley Surrey

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