How to Detect a Gas Leak — UK Safety Guide
A gas leak indoors is a life-threatening emergency. Here is exactly what to do — and what NOT to do — plus how to check for slow leaks.
Step-by-step method
1. If you smell gas — immediate action
Turn off the meter emergency control valve (yellow/red handle at the meter). Open all doors and windows. Do NOT switch anything electrical on or off — sparks ignite gas.
2. Evacuate and call 0800 111 999
National Gas Emergency line — free, 24/7. They respond within 1 hour. Do not re-enter until an engineer confirms safe.
3. Never search with a naked flame
Lighter flame near a leak = explosion. Use soapy water on suspected joints — bubbles show the leak.
4. Slow leak detection
Turn off all appliances. Check the meter — if the test dial turns, you have a leak. Call National Gas Emergency.
Frequently asked questions
What does natural gas smell like?+
Rotten eggs — the mercaptan added to odourless natural gas. If you smell it, act.
How much does emergency gas leak repair cost?+
Free emergency capping (National Grid). Actual repair by a Gas Safe engineer £120–£400 depending on where.