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If you've searched for how to solder copper pipes, there's a decent chance you're dealing with a leak.

Copper pipework typically lasts 70-80 years, so if yours is dripping, corrosion has usually had time to eat a small "pinhole" through the pipe wall from the inside out.

Soldering is the traditional way to join copper pipe permanently, and it's still what most plumbers use for anything carrying mains water pressure. It's a satisfying skill to learn, but it involves an open flame near your home's pipework, so it's worth being honest with yourself about your comfort level before you start.

It's often quicker and a lot safer to get a plumber or heating engineer to do the work for you.

Tools and safety kit you'll need

• Lead-free solder

• Flux and a flux brush

• Blowtorch (propane or MAP gas - MAP gas burns hotter and is faster on wider pipe)

• Pipe/tube cutter

• Deburring tool or emery cloth

• Wire brush or wire wool

• Heatproof mat

• Wet rag

• Heatproof gloves and eye protection

Safety first

Naked flames are an obvious fire and burn risk, so always wear gloves and eye protection - solder can spit when it's heated.

Flux also contains rosin, which can irritate your eyes, throat, and lungs if you breathe it in, so work in a ventilated space and avoid leaning directly over the joint.

Before you start any work on the pipework itself, isolate the water supply to the section you're working on and open a nearby tap to drain any residual water.

Soldering a pipe that still has water in it essentially can't be done - the water absorbs the heat and stops the joint reaching soldering temperature, so you'll need to fully drain the line first.

Copper pipe soldering checklist

• Isolate and fully drain the water supply

• Cut pipe square and deburr the edges

• Clean pipe and fitting until bright

• Apply flux evenly to both surfaces

• Heat the fitting, not the solder

• Test thoroughly once cooled

How to solder a copper pipe

1. Cut the pipe to length

Measure and mark the pipe, then use a pipe cutter to make a clean, square cut. Tighten the cutter gradually and rotate it around the pipe rather than forcing it through in one go, or you risk denting the copper.

2. Deburr the cut ends

Run a deburring tool or the reamer on your pipe cutter around the inside edge of the cut to remove sharp burrs, then tap the pipe to clear any shavings. Skipping this step is one of the most common reasons a joint doesn't seat properly.

3. Clean the pipe and fitting

Use emery cloth or a wire brush on the outside of the pipe end and a wire brush inside the fitting until both surfaces are bright and shiny. Any dirt, oxidation, or old flux residue will stop the solder bonding properly, so don't rush this part.

4. Apply flux

Brush an even, thin layer of flux onto the cleaned pipe end and the inside of the fitting.

5. Assemble the joint

Push the pipe fully into the fitting until it seats, then twist slightly to spread the flux evenly. Wipe away any excess flux that squeezes out with a clean cloth.

6. Protect the surrounding area

Position a heatproof mat behind and beneath the joint, especially near timber, plastic fittings, or anything flammable nearby.

7. Heat the joint

Light the blowtorch and adjust it to a steady, controlled flame. Heat the fitting itself, not the solder wire directly - once the fitting is hot enough, touching the solder to the joint will melt it and draw it into the gap by capillary action.

8. Apply the solder

Run the solder wire around the circumference of the joint, feeding roughly half an inch of solder for every half inch of pipe diameter. You should see a thin, even line form all the way around.

9. Turn off the torch safely

Extinguish the flame and set the torch down somewhere heatproof - the nozzle stays hot for a while afterwards.

10. Inspect the joint

Check for a continuous, even line of solder right around the fitting with no visible gaps.

11. Clean off excess flux

Wipe the warm joint with a wet rag to remove any remaining flux residue before it discolours the pipe.

12. Test for leaks

Once the pipe has fully cooled, turn the water supply back on and check the joint closely for drips or weeping, ideally leaving it under pressure for a few minutes before you consider it done.

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Soldering alternatives if you'd rather avoid a flame

If working with a blowtorch indoors doesn't appeal, push-fit (push-to-connect) fittings are a legitimate flame-free alternative for many jobs.

They connect copper, and often plastic pipe, in seconds without heat, though some plumbing situations still call for a soldered joint for a fully permanent, code-compliant connection - particularly on pipework carrying full mains pressure.

If your leak is at a tap connection rather than mid-pipe, our guide on how to fit a tap may solve it without soldering at all - otherwise, a plumber can advise on the best fitting for your specific pipework.

Should you hire a professional instead?

Soldering copper pipe isn't technically complicated, but the combination of an open flame, your home's water supply, and (often) working in a tight, awkward space is exactly why many people choose to leave it to a plumber.

It's also worth bearing in mind that a poorly soldered joint on a pressurised water line won't announce itself as a problem until it fails - sometimes inside a wall or under a floor.

When it's worth calling a plumber:

• The pipe you need to join is still wet and you can't fully isolate the supply

• The joint is in a tight or hard-to-reach space, increasing the fire and injury risk

• You're working on a pinhole leak in old pipework that may indicate wider corrosion

• You've never used a blowtorch indoors before and this is a job that matters (e.g. pipework buried in a wall)

See our plumber cost guide for typical hourly rates, or our guide to plumber call-out charges if you need someone out quickly for a leak.

On Checkatrade, you'll only find trades who meet our high standards and pass up to 12 checks.

Any plumber you hire through Checkatrade is covered by our guarantee, and you can review their profile, past work, and verified customer reviews before booking.

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