I have drilled into a water pipe — what do I do?
Stopping the water first, why leaving the drill bit in the hole buys you time, working out which pipe you have hit, and what a proper repair involves rather than a patch.
- Difficulty
- beginner
- Time
- 30 min
- Read
- 6 min
- Safety
- warning
Short answer
Leave the bit in the hole — it partly plugs it — while you turn the water off. Mains stopcock for a cold supply, or drain the system for heating. Then isolate the electrics if water has run near any. Only once the pipe is dry and depressurised can it be repaired, and a buried pipe needs cutting out and jointing properly rather than sealing over.
The first thing to understand is that the amount of water coming out has almost nothing to do with how bad the damage is, and everything to do with the pressure behind it. A mains cold pipe will empty a great deal of water into a wall very quickly; a heating pipe will produce less but it will be hot and full of dirty system water that stains. Either way the sequence is the same: stop the water, then stop the electricity, then think.
Safety
What you'll need
- Buckets and towels
- Knowledge of where your stopcock is
- Torch
- Pipe repair clamp or a compression coupler (optional)
Step by step
- Leave the drill bit where it is for a moment.The bit is partly blocking the hole it made. Withdrawing it immediately turns a leak into a jet. Support the drill, get a bucket and a towel under it, and go and turn the water off first.
- Turn the water off at the right place.For a cold mains pipe, the internal stopcock — usually under the kitchen sink, in a downstairs cupboard or under the stairs. For a hot or a stored cold pipe, the gate valve on the tank feed if there is one, or drain the tank. For a heating pipe, turn the boiler off and shut the valves at either end of the run, or drain the system.
- Open the taps to drop the pressure.Once the stopcock is off, open the lowest cold tap in the house to drain the standing water in the pipes. This turns a pressurised leak into a dribble and lets you work.
- Switch the electricity off if water has gone anywhere near it.Water running down inside a wall or across a ceiling reaches cables, sockets and light fittings. If there is any doubt, switch off at the consumer unit and leave it off until things are dry and, if necessary, checked.
- Now withdraw the bit and see what you have.With the pressure off, remove the drill and look. Copper, plastic or steel; a small nick or a hole through; heating pipe (usually running to a radiator) or supply pipe. What you do next depends entirely on this.
- Open the wall up enough to work.A repair on a buried pipe means exposing at least 150mm either side of the damage so a proper joint can be made with the pipe cut back to sound metal. Chipping away just enough to see the hole is not enough and produces repairs that fail.
- Make a proper joint, not a patch.Cut the damaged section out and joint in a new piece with compression or push-fit fittings, or solder if you are competent with it. A repair clamp or self-amalgamating tape is an emergency measure to get you through the night, not a buried repair — anything hidden in a wall must be a joint you would be happy never to see again.
- Test under pressure before closing anything.Restore the water, run it up to full pressure, and leave the repair visible and dry-wiped for at least an hour, checking with a torch and a dry tissue. Only then make good the plaster.
- Deal with the water that got in.Lift what you can, get air moving, and use a dehumidifier if a significant volume went into a floor or a ceiling. Water in a wall causes damp and staining long after the leak is fixed, and plasterboard that has been soaked usually has to come out.
Tips
- Know where your stopcock is, and check it turns, before you need it. A seized stopcock discovered during a leak is a much worse evening than one discovered on a quiet Sunday.
- If you cannot find or turn the internal stopcock, the external one in the pavement or the front garden can be closed with a stopcock key. Water companies will usually attend an emergency where the supply cannot be isolated.
- A pipe freezing kit is worth knowing about: it freezes a plug of ice in a pipe so a short section can be worked on without draining a whole system. Hire shops stock them.
- Photograph the pipe run once the wall is open, before you make good. Knowing exactly where the pipes are is the best possible outcome of a bad afternoon.
- Central heating water is black and it stains everything it touches. Get towels down early and rinse anything it lands on quickly.
If it doesn't work
Water is still coming out after the stopcock is off
Cause: You have hit a pipe fed from a tank rather than from the mains, or there is a lot of standing water in the run — Fix: Open the taps to drain down, and shut the gate valve on the tank outlet or tie up the ball valve and drain the tank. Stored water gravity-feeds regardless of the stopcock.
Hot dirty water and the radiators are cooling
Cause: You have drilled a central heating pipe — Fix: Turn the boiler off, close the valves at both ends of the affected radiator circuit if you can, and drain the system from the lowest drain-off point before repairing.
No water appeared but the drill went suspiciously easily
Cause: You may have gone through an empty pipe, a plastic waste pipe, or a pipe on an isolated circuit — Fix: Do not assume it is fine. Open the wall enough to see, because a nicked pipe that is not currently in use will leak the moment it is.
A stain appears on the ceiling below some days later
Cause: A slow leak from the damaged pipe that was not fully repaired, or water that soaked into the structure — Fix: Isolate again, open up and inspect the repair. A joint that weeps is a joint that was not made properly and it will not improve.
Questions people ask
Can I just seal the hole with sealant or tape?
Not for anything that stays buried. Self-amalgamating tape and a proprietary repair clamp will hold a low-pressure leak temporarily and are genuinely useful to get through until morning. A permanent repair means cutting the damage out and jointing in new pipe.
How do I know whether I hit a heating pipe or a water pipe?
Heating pipes are usually 15mm, run to and from radiators, and carry hot black water. Supply pipes run from the stopcock towards taps and appliances and carry clean water. If the radiators go cold and the boiler pressure drops, it was heating.
Will my insurance cover it?
Escape of water is a standard peril on most buildings policies, and accidental damage cover — which is often optional — is what typically covers the damage you caused to the pipe itself. Ring them early rather than after you have stripped the wall out.