The move most people skip
A temporary patch is the second-best answer. The best one is isolation: turn the water off, open the taps, let the pipe empty, and the leak stops dead. If the leak is on a branch rather than the main run, you may be able to isolate just that branch — most basins, toilets and washing machines have a small service valve on the feed that closes with a flat screwdriver, and most radiators close on their own two valves.
Patch only when you genuinely cannot live without the supply until it is repaired, or when the leak is on a heating circuit you want to keep running in cold weather. A patch is a way of buying time, not a repair.
What actually holds, and for how long
| Method | Works on | Honest limit |
|---|
| Pipe repair clamp (metal shell, rubber liner, two bolts) | A pinhole or short split on straight, accessible copper or steel | The most reliable of the lot. Still a temporary fix: it seals the hole, it does not stop the corrosion that made it. |
| Self-fusing silicone tape (sometimes sold as self-amalgamating) | Pinholes and weeping joints on copper and plastic, including bends | Hours to days on a low-pressure heating circuit. Much less on mains cold, which in London can be high pressure. |
| Two-part epoxy putty stick | Pinholes on a dry, roughened, fully depressurised pipe | Needs the pipe bone dry and out of service while it cures. Fails quickly on a pipe that flexes or gets hot. |
| Rubber offcut and two hose clips | An improvised version of the clamp above | Will slow a weep long enough to get a bucket under it. Do not rely on it overnight. |
| Bucket, towels and a drip tray | Anything | Undignified and genuinely effective while the water is off and you are waiting. |
How to apply a patch so it holds
- Turn the water off and open the taps. Nothing bonds to a pipe with water moving through it.
- Dry the pipe properly. Kitchen paper, then a few minutes of air. Wet copper defeats tape and putty alike.
- Clean the surface. Wire wool or emery cloth on copper, back to bright metal, then wipe the dust off.
- Cover well beyond the hole. A clamp centred on the split; tape starting about 50mm clear of the damage, stretched hard as you wrap, overlapping each turn by half its width, and finishing 50mm clear the other side.
- Bring the water back slowly. Open the stop tap a quarter turn, wait, watch, then open the rest of the way. A sudden surge pops a fresh patch.
- Put a tray and a towel under it anyway, and look at it again before you go to bed.
Leaks that are not temporary fixes at all
Some of what gets called a leaking pipe is a five-minute job you never need anyone for:
- A weeping compression nut. The nut behind a radiator valve or under a basin, damp but not running, will often stop with an eighth of a turn from a spanner while holding the valve body still. An eighth. Overtightening crushes the olive and turns a weep into a jet.
- A push-fit joint that has crept. Push-fit fittings need the pipe fully home against the stop. A joint that has been nudged out can often be pushed back and re-secured with the proper collet clip.
- A dripping tap. A washer or a ceramic cartridge, and the service valve under the basin isolates it while you work. Changing a tap washer and changing a tap cartridge cover both.
If the drip returns, stop. Repeated tightening is how a small job becomes a burst pipe.
What never to patch
- Anything carrying gas. Not with tape, not with putty, not ever. Work on gas fittings in a domestic property must be done by a Gas Safe registered engineer under the Gas Safety (Installation and Use) Regulations 1998. If you smell gas, leave the appliance alone and call the national gas emergency line — the number is on your gas bill.
- A pipe behind a boiler casing. Removing the casing is gas work. Turn the boiler off and the water off instead.
- A boiler discharge pipe that is dripping. That is a safety valve doing its job, and blocking or patching it removes the safety route. See what a dripping overflow pipe means.
- Lead pipework. Old lead supply pipe is soft, deforms under a clamp and splits beside the patch. It wants replacing, not holding together.
- Any pipe you cannot see all the way round. A patch on the visible face of a pipe buried in a wall or a joist notch is a guess, and the water goes somewhere you are not watching.
- A pipe near live electrics. Isolate the circuit first, or leave it.
When a patch is the wrong decision entirely
Buying time makes sense when the pipe is accessible and someone is coming. It makes no sense at all when the leak is hidden, because the leak you can reach is rarely where the damage is happening. A pinhole in a 15mm heating pipe under screed will not show on a floor for months while it quietly destroys the screed and the insulation under it. If your pressure gauge is dropping and there is nothing visible, the question is not how to patch it, it is where it is: that is what the pressure hub covers and what an emergency leak repair visit starts with.
The same applies to the private supply pipe running from the boundary to your house. You cannot clamp a leak under a driveway. That one shows up as a meter that keeps turning with everything off, and it is a supply pipe repair.
What a proper repair involves
On accessible copper, the split section is cut out and a new piece soldered or coupled in, and the run is checked either side for the corrosion that caused it. On plastic, the fitting is replaced rather than re-used. On a hidden pipe, the leak is located first — pressure test, thermal imaging, tracer gas on a drained circuit — so the wall or floor is opened once, in the right place.
We charge £150 per hour, fixed before we attend, and if we are hunting a hidden leak and do not find it you do not pay for the time spent looking. What the total comes to depends on the hours, so treat anyone quoting a final price unseen with suspicion.
If what you are holding together is a crack rather than a pinhole, read cracked pipe: what to do now, because a clamp holds a crack for less time than it holds a hole.
