Protect people, use the emergency control valve only where safe, report from safety, and restore gas only after the fault is repaired and proved tight.
Natural gas has no smell of its own. A strong, distinctive odour (a stenchant) is added so that people notice an escape early and can act. Treat any reported smell of gas, indoors or outdoors, as an emergency until it is proved otherwise: escaping gas can reach a flammable concentration and be ignited by something as small as a light switch. Work in a fixed order: protect people, make safe where you can do so safely, report, and only then find and repair the fault.
Protect people and avoid ignition
- Warn others and get everyone out of the affected area, away from danger and into fresh air. Do not use a light switch or doorbell to warn people.
- Avoid flames and smoking, and operate nothing electrical, on or off. A switch may spark when its contacts open or close, and that can ignite a flammable gas-air mixture. The same goes for a light pull, doorbell, thermostat, extractor fan, plug or mobile phone in the affected area.
- Ventilate by opening doors and windows, and only where it is safe.
- If anyone has symptoms such as headache or dizziness, get them into fresh air and seek urgent medical help as well as reporting the escape.
The emergency control valve
The emergency control valve (ECV) is where anybody, not just an engineer, can stop gas entering the property. It shuts off the whole installation, not one appliance. It is usually next to the gas meter and is turned by hand: when the handle lies across the pipe, the gas is off. It must be readily accessible, so keep it clear and make sure the customer knows where it is and how to turn it off.
Close it, and open doors or windows, only where you can do so safely: neither action may require entering or staying in danger. Never enter a gas-filled cellar, basement or other dangerous space to reach the valve or a window; leave and make the call instead. If the control cannot be reached or will not close, withdraw and tell the emergency service that isolation has not been achieved. Do not force the handle, dismantle the valve or open a gas connection.
Decision check: the caller is already outside, but the meter is in the affected cellar. Keep the caller out and report the inaccessible control. Sending them downstairs would reverse the protective action already taken.
Report from a safe place
- For network natural gas in Great Britain, call 0800 111 999 promptly: the dedicated gas emergency freephone line, separate from 999 and from NHS 111. For LPG, use the supplier's emergency arrangements. Call 999 for a fire or if there is immediate danger to life.
- Make the call from a safe place. Do not stay inside using a phone while tracing the smell.
- Do not delay the call to find the exact leak: you do not need to identify a leaking joint, obtain a meter serial number or prove a failed tightness test first. If the escape cannot be stopped at the property, the gas emergency service attends to make it safe. Do not leave the customer to monitor the danger.
- Tell the responder what you saw and what isolation you carried out. A smell that persists after the ECV is closed still needs reporting: it does not show whether gas is left from earlier, is still escaping or is coming from upstream of the valve.
- Follow the responding service's instructions and wait for the all-clear before going back in.
Advising a member of the public
- A smell outdoors near a meter is still a possible escape; open air does not make it safe. Avoid ignition sources and call the gas emergency line straight away.
- Do not attempt a repair or touch the meter.
- Do not delay the call to find a meter serial number or the leaking joint.
What a quieter situation does not prove
An open window, a fading smell or a silent CO-only alarm does not show that an escape has stopped: a CO-only alarm does not detect unburnt fuel gas. Odour disappearing after ventilation tells you about the room air; it cannot certify sound pipework. Emergency attendance may make the situation safe but leave the repair to a competent engineer, so do not reopen the supply for normal use until safety has been established.
Where escaping gas collects
- Natural gas is mostly methane, which is lighter than air, so it tends to rise; indoors it can still build up to a mixture that will ignite.
- LPG is heavier than air, so it sinks and can pool in cellars, basements, drains and other low places, where it can ignite or displace breathable air. Keep people and ignition sources away from low areas near an LPG escape.
- Density gives a tendency, not a safe floor or room: airflow and building routes affect where escaped gas spreads, so floor level alone does not make anywhere a safe place to remain. Do not use occupants to search for the strongest smell.
Diagnosis comes after control
Trace-and-repair is not the first action while gas is escaping uncontrolled: hunting for the leak while gas keeps building leaves everyone exposed. Once the escape is controlled, a competent person locates and repairs its cause using the applicable procedure.
Where valid sectional tests are appropriate, a pass in one section and failure in another narrows the search to the failed section. It does not identify the first joint after a valve, prove every joint in the failed section leaks, or establish the safety of the whole installation.
Repair and check before normal use
Making the emergency safe does not necessarily include repairing the customer's installation. Arrange the required competent repair, then carry out the required tightness test on the affected installation and the applicable purging and recommissioning checks before opening the supply again for normal use or relighting. Keep it safely isolated if that cannot be achieved.
Controlled gas admission for a prescribed test is different from permission to use a known leaking installation. A cooker lighting successfully does not prove gas-tightness, and a pipework tightness result does not establish every appliance's combustion or flue safety.
Which regulation applies?
GSIUR regulation 37 deals with escapes outside the network-gas scope, including LPG; its paragraph (7) excludes escapes from a network and fittings supplied by that network. Network natural-gas escape duties are covered by regulation 7 of the Gas Safety (Management) Regulations 1996.