In a plumbing emergency, the priority is to stop the flow or stop using the affected system, then protect people and the property before attempting diagnosis. For a burst or serious leak, turn off the internal stop tap or suitable isolation valve, switch off heating where appropriate and keep water away from electrical equipment. If water has reached electrics and it is safe to do so, isolate the affected electrical supply.
A suspected gas leak is not an ordinary plumbing leak. Open doors and windows, turn off the gas at the meter if you know how and it is safe, avoid switches or flames, leave the area if necessary and use the National Gas Emergency number 0800 111 999. For a professional assessment or installation, Best Gas London Ltd can help you decide what is appropriate for the property and the problem in front of you.
Originally published: 9th August 2024 | Last updated: 16th August 2026
Plumbing Emergency: The Short Answer
- Burst water pipe: turn off the water supply, switch off the boiler/heating if appropriate and drain cold outlets as advised for the system.
- Water near electrics: do not touch wet electrical equipment; isolate electricity only if it can be done safely.
- Overflowing toilet: stop flushing, isolate the cistern if possible and stop other fixtures if a shared drain is backing up.
- Sewage: keep people and pets away and minimise use of affected drains until the blockage is cleared.
- Suspected gas leak: call 0800 111 999, ventilate, avoid ignition sources and do not attempt a repair.
- After containment: photograph damage, arrange repair and dry affected materials rather than assuming the problem ends when the water stops.
Think in This Order: People, Utilities, Property, Repair
The first minute is about safety. If there is an electrical hazard, gas smell, scalding water or sewage, keep people away from the affected area. Do not wade into water to reach an electrical switch and do not create sparks if gas is suspected.
Next, isolate the utility causing damage. For clean-water leaks, that may be a local service valve or the internal stop tap. For a central-heating leak, the boiler and heating circuit may also need isolation. For drainage backups, the correct action is usually to stop adding water rather than opening a supply valve.
Only after the flow is controlled should you inspect the source, take photographs, move possessions and consider temporary containment. A quick but unsafe repair is never more important than proper isolation.
Six Plumbing Emergencies and the First Priority
Burst Pipe
Shut off the water supply and reduce water remaining in the pipework. Protect nearby electrics and ceilings below the leak.
Major Hidden Leak
If water is spreading through walls or ceilings, isolate the main supply and do not puncture a bulging ceiling while standing beneath it or near electrics.
Overflowing Toilet
Stop flushing and isolate the toilet cistern if possible. If other drains are also affected, treat it as a downstream blockage.
Sewage Backup
Stop using toilets, sinks and appliances connected to the affected drainage route. Keep people away from contaminated water.
Boiler Water Leak
Turn the boiler off using normal user controls and isolate water/heating as appropriate. Do not remove the boiler casing.
Gas Smell
Ventilate, avoid switches and flames, turn off gas at the meter if safe, leave if necessary and call the National Gas Emergency service on 0800 111 999.
Emergency Plumbing Decision Table
| Emergency | Immediate action | Do not | Who to call |
|---|---|---|---|
| Burst mains-water pipe | Close internal stop tap; contain water; protect electrics. | Keep using water or rely on a bucket while damage continues. | Emergency plumber; electrician if electrics are affected. |
| Heating pipe / radiator leak | Turn heating off; isolate radiator or circuit where possible. | Open boiler casing or repeatedly repressurise a leaking system. | Heating engineer / plumber. |
| Ceiling leak | Stop water source if possible; keep people away from sagging ceiling. | Stand beneath saturated plaster or touch wet lights. | Plumber plus electrician/building repair as needed. |
| Blocked toilet with rising water | Stop flushing; isolate cistern if needed; plunge cautiously. | Add more water or chemicals blindly. | Plumber/drainage contractor if not local. |
| Sewage coming up drains | Stop using affected drains; restrict access; ventilate. | Spread contaminated water through the home. | Drainage contractor / plumber. |
| Gas smell | Ventilate, avoid sparks, call 0800 111 999. | Operate electrical switches or search for leak with a flame. | National Gas Emergency service, then Gas Safe engineer as directed. |
| No water throughout property | Check water-company status and neighbours. | Dismantle plumbing before ruling out supply work. | Water company if network issue; plumber if property-specific. |
| Sudden very low pressure + meter movement | Isolate supply if leak suspected and inspect for damage. | Ignore it because no water is visible. | Plumber / leak-detection specialist. |
Know Your Stop Tap Before You Need It
WaterSafe advises homeowners to know where the internal stop tap is and make sure it operates. In many homes it is under the kitchen sink, but location varies. Test it gently during normal conditions; do not force a seized valve during an emergency.
What to Do During a Major Water Leak
1. Keep People Safe
Move children and pets away, especially where ceilings are saturated, sewage is present or water is near electrical equipment.
2. Shut Off the Water
Use the nearest suitable isolation valve or the internal stop tap. If it will not move, do not apply excessive force that could break the valve.
3. Turn Off Heating Equipment as Appropriate
Switch off the boiler/heating using normal controls if the water supply is isolated or the leak involves the heating system. Follow manufacturer guidance for your system.
4. Manage Electrical Risk
If water has reached electrical fittings, do not touch wet equipment. Isolate power only from a dry, safe location; otherwise keep clear and call an electrician.
5. Drain and Contain
For a burst clean-water pipe, opening cold taps after isolation can help drain the system. Collect water, move belongings and use towels or containers without putting yourself at risk.
6. Call and Describe the Problem
Tell the plumber what has been isolated, where water is appearing, whether heating or electrics are affected and whether the leak is clean water, heating water or sewage.
7. Document and Dry
Photograph the damage for insurance where relevant, then begin safe drying and ventilation once the leak is repaired. Hidden moisture can remain after visible water is gone.
Emergency Containment vs Permanent Repair
| Measure | What it achieves | What it does not achieve | Next step |
|---|---|---|---|
| Closing stop tap | Stops incoming mains water. | Does not empty stored tanks or repair the leak. | Drain safely and repair source. |
| Closing local isolation valve | Keeps the rest of the property supplied if successful. | Does not help if the valve itself is leaking or failed. | Repair isolated component. |
| Pipe repair clamp | Can reduce leakage temporarily on suitable pipe. | Does not remove corrosion or guarantee long-term integrity. | Plan a permanent pipe repair. |
| Bucket / towels | Limits spread of water. | Does not stop continuing flow. | Isolate water first. |
| Resetting boiler | May clear a transient user-level fault. | Does not fix a leak or internal safety fault. | Stop repeated resets and arrange diagnosis. |
| Drain plunger | May clear a local soft blockage. | Does not fix downstream structural problems. | Escalate if several fixtures are affected. |
Burst Pipes: What to Do After the Water Is Off
Once the stop tap is closed, residual water may still discharge from pipework, storage tanks or the heating circuit. Open cold taps as appropriate and use containers while monitoring ceilings and rooms below.
Do not restore the supply until the failed pipe is properly repaired and disturbed joints are checked. Refill slowly so a second weak point does not produce another uncontrolled leak.
Leaks Above Ceilings Need Extra Caution
Water can travel along joists and cables, so the visible drip may be away from the source. Saturated plasterboard can become heavy and fail. Keep the area below clear and do not casually puncture a bulging ceiling near electrical fittings.
A plumber may stop the source, but damaged electrics, plaster, insulation and flooring may need separate inspection and drying. Treat secondary damage as part of the incident.
Sewage Backups Are Different from Clean-Water Leaks
Sewage introduces contamination rather than simply water damage. Stop using connected fixtures, prevent access and arrange drainage clearance. Wear appropriate protection if you must handle contaminated materials.
After the blockage is resolved, clean and disinfect affected surfaces appropriately and remove porous materials that cannot be safely restored.
Gas Smells Need the Gas-Emergency Process
HSE advises anyone suspecting a gas leak to contact the National Gas Emergency service on 0800 111 999, ventilate by opening doors and windows and shut off the gas at the meter if they know where it is.
Do not operate electrical switches, smoke or use naked flames. A householder should not search for the leak by dismantling an appliance; follow the emergency operator’s instructions and use Gas Safe engineers for subsequent gas work.
Prepare Before an Emergency Happens
Label the internal stop tap, know which valves isolate toilets and appliances, keep the plumber and insurer details accessible and make sure household members know not to force unfamiliar valves.
Photograph important plumbing locations during a calm moment: stop tap, water meter, boiler filling arrangement and key isolation valves. That information is extremely useful when water is already escaping.
Emergency Plumbing Preparation Checklist
Emergency Plumbing Preparation Checklist
- Locate and label the internal stop tap.
- Gently test the stop tap periodically so you know it operates.
- Know how to switch the boiler off using normal user controls.
- Know the location of the consumer unit but never approach it through water.
- Keep the National Gas Emergency number 0800 111 999 available.
- Keep a working torch where it can be reached safely.
- Check visible flexible hoses and appliance connections for deterioration.
- Insulate vulnerable pipes before freezing weather.
- Keep an emergency plumber contact accessible.
- Know what your home insurance expects after an escape-of-water incident.
Do Not Let Urgency Override Safety
A plumbing emergency creates pressure to act quickly, but do not enter water near live electrics, climb under a collapsing ceiling, handle sewage without precautions or dismantle gas equipment. The correct emergency action is often isolation and evacuation from the immediate hazard, not a hurried repair.
When to Call for Emergency Plumbing Help
Urgent help is appropriate for uncontrolled leaks, burst pipes, sewage entering the home, a leak you cannot isolate, severe ceiling water damage, loss of essential sanitation or heating-water leaks that prevent safe system operation. You can review the company’s main heating and plumbing services before deciding what type of visit or work is likely to be needed.
Suspected gas leaks follow the gas-emergency route first—0800 111 999—and gas repairs should then be carried out by a competent Gas Safe registered engineer. You can also read more about the Best Gas team or contact Best Gas with the property details, symptoms and any relevant appliance information.
Need Help with an Active Plumbing Emergency?
If it is safe, isolate the water and tell us what system is affected, which valve has been closed, where water is appearing and whether electrics, heating or drainage are involved.
Call Best Gas London Ltd on 07534 110 487 to discuss the next step.