Plumbing Emergencies: What to Do Before the Plumber Arrives (Could Save You Thousands)

Plumbing emergencies don't politely wait until business hours. The worst ones happen on a Sunday evening, on Christmas Day, or while you're on holiday. By the time the plumber arrives — even if response is fast — significant damage may already be done unless you take the right action in the first few minutes.

I run a 24/7 emergency plumbing line for Orpington, Bromley and Kent. The customers who minimise damage are the ones who know what to do before I arrive. This guide tells you exactly that — broken down by emergency type — so you can act fast and confident when something goes wrong.

Burst Pipe

The most damaging emergency. A burst pipe under mains pressure can release thousands of litres in an hour, flooding ceilings, wrecking floors, and triggering insurance claims that take months to resolve.

What to do — in order:

1. Turn off the internal stopcock immediately. Clockwise to close. This isolates the entire property.
2. Open all cold taps to drain the system fast. Less water in the pipes = less water leaking.
3. Turn off your boiler or heat pump — without water flow, heating systems can damage themselves.
4. Switch off electrics at the consumer unit if water is anywhere near electrical fittings or sockets.
5. Move valuables and electronics out of the affected area.
6. Place buckets and towels to catch ongoing drips.
7. Call an emergency plumber.
8. Take photos and videos for your insurance claim before cleanup.

Don't try to fix a burst pipe with tape or sealant unless absolutely necessary as a temporary measure — and only on visible, accessible pipework with low pressure.

Overflowing Toilet

Water plus gravity plus contamination — overflowing toilets cause more damage than people expect because they keep flowing until manually stopped.

What to do:

1. Stop the flush mechanism. Lift the cistern lid and lift the float ball to stop water filling.
2. Turn off the toilet's isolation valve. There's usually a small valve where the cold supply enters the cistern. Turn the screw 90° with a flathead screwdriver.
3. If you can't find an isolation valve, turn off the internal stopcock.
4. Don't keep flushing hoping it'll clear — you'll just add more water.
5. If safe, try a plunger or toilet auger to clear the blockage.
6. Use towels to contain the spill from spreading to other rooms.
7. Disinfect thoroughly after the issue is resolved (toilet water is contaminated).

Boiler or Heating System Leak

A leak from your boiler, heat pump or heating system pipework can be subtle (slow pressure loss requiring frequent topping up) or dramatic (water on the floor near the unit).

What to do:

1. Turn off the boiler or heat pump at the appliance and at the electrical isolator.
2. Turn off the cold water feed to the heating system (separate from the main stopcock — usually a small valve near the boiler).
3. Find the leak source if visible. Most heating leaks come from radiator valves, the boiler itself, or visible pipework joints.
4. Place a container under the leak.
5. Don't keep topping up the system pressure — you're just adding more water to leak out.
6. Call a heating engineer (Gas Safe for gas, ASHP-qualified for heat pumps).

Hot Water Cylinder Failure

Unvented cylinders (Megaflo, Gledhill, Vaillant) are pressurised systems. When they fail, they can fail dramatically — but more often they leak slowly from a relief valve or fitting.

What to do:

1. Turn off the cold water feed to the cylinder (usually a clearly-marked valve where the cold pipe enters).
2. Turn off the heat source (immersion heater, boiler, or heat pump).
3. Don't try to drain the cylinder yourself — this is G3-qualified work for safety reasons.
4. If water is dripping from the external discharge pipe outside your house, this is the safety relief valve doing its job — don't try to stop it.
5. Call a G3-qualified engineer.

Frozen Pipes

UK winters can drop below freezing for days at a time, and exposed or unlagged pipework freezes. Frozen pipes don't leak immediately — but when they thaw, they often split.

What to do:

1. Turn off the internal stopcock first — this minimises damage when the pipe thaws and potentially splits.
2. Open the affected tap fully to relieve pressure as the ice melts.
3. Thaw the pipe slowly with a hairdryer on low, hot water bottles, or warm towels. Start nearest the tap and work backwards.
4. NEVER use naked flames, blowtorches or boiling water — pipes will split or you'll start a fire.
5. Check for leaks immediately after thawing — a thaw can reveal a split.

Blocked Drain or Sewage Backup

Water coming up the wrong way — out of a shower drain, gully, or worst of all toilet — usually indicates a blocked drain. This is genuinely urgent.

What to do:

1. Stop using all water in the property immediately. No flushing, no taps, no washing machines.
2. Check your external drains for visible blockages (leaves, debris).
3. Don't pour drain unblocker down the affected drain — chemicals make later clearance more dangerous and damage pipework.
4. Call a drainage specialist or your water company if it's the main sewer (often the water company's responsibility).

No Hot Water Suddenly

Not always a true emergency, but inconvenient. Quick checks before calling:

• Boiler pressure — should be 1–1.5 bar cold. If lower, top up using the filling loop.
• Programmer/timer — has it changed mode?
• Power — is the boiler/heat pump still receiving electricity?
• Trip switch — has the immersion or boiler tripped?
• Gas supply (gas systems only) — has the gas been cut off?

What to Tell the Plumber When You Call

A clear initial call gets help to you faster. Have ready:

• Your full address with postcode
• Brief description: "burst pipe under kitchen sink, mains is now off"
• What you've already done
• Whether anyone is in danger or there's electrical risk
• Whether children, elderly, or pets are affected

Insurance Claims After a Plumbing Emergency

Most home insurance covers damage caused by leaks but not the cost of fixing the leak itself. After the immediate emergency:

• Document everything with photos and videos before cleanup
• Keep all receipts (emergency call-out, repairs, replacements)
• Don't dispose of damaged items until your insurer has assessed
• Get the work done by a qualified, insured plumber — your insurer may reject claims for work done by uninsured tradespeople

Prevention: Stop Emergencies Before They Happen

Most emergencies are preventable with basic maintenance:

• Annual servicing of unvented cylinders and heat pumps catches small problems before they become emergencies
• Lag exposed pipework in lofts, garages and outbuildings before winter
• Replace flexible hoses on washing machines, dishwashers, and under sinks every 5–10 years
• Test your stopcock twice a year so you know it works when you need it
• Address slow leaks immediately — they always get worse, never better