Stop condensation dripping from cold water pipes

Wrap cold water pipes in foam insulation and cut room humidity so condensation stops forming and dripping.

AB-01Check it's condensation, not a leakDry the pipe completely with a cloth, then leave it for 30 minutes without running any taps or appliances nearby. If moisture reappears with no dripping tap or running water, it's condensation. If you see a steady drip or a wet patch that keeps coming back on its own, treat it as a leak: turn off the water at the stopcock, usually under the kitchen sink, and get it checked before doing anything else.

1 each · Cloth or old towel

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AB-02Find every pipe that's sweatingFollow the cold pipe run through the house and check for bare metal or plastic pipe passing through warm, humid rooms. Common spots are under the kitchen sink, in bathrooms, and where a cold feed runs through an airing cupboard. Mark every length that's cold and damp to the touch - there's often more than one.

AB-03Measure the pipe and the runMeasure the pipe's outside diameter with a tape measure - UK cold pipes are usually 15mm or 22mm. Measure the total length of each run you need to cover and add about 10% extra for waste at joints and bends.

1 each · Tape measure

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AB-04Buy the right foam laggingChoose foam pipe insulation matched to your pipe size (15mm or 22mm bore) with at least 13mm wall thickness. In colder spots like a loft, use thicker 19mm or 25mm foam for better protection. Pre-slit, self-seal lagging is easier to fit and needs less taping.

4 each · Foam pipe insulation, 15mm bore, 13mm wall, 1m length

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1 each · Self-adhesive lagging tape roll

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1 each · Utility knife

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AB-05Clean and dry the pipe before fittingWipe the whole length of pipe with a dry cloth to remove dust, grease and any leftover condensation. Insulation fitted over a damp pipe traps moisture underneath and won't stop the dripping, so the pipe must be completely dry before you start.

AB-06Fit the foam laggingOpen the pre-slit foam along its length and clip it over the pipe like a hinge, working along the run from one end to the other. Push each length firmly against the next so there are no gaps, and trim pieces with a utility knife to fit round bends.

AB-07Seal every joint, end and elbowTape over every join between lengths of lagging with the self-adhesive lagging tape, and seal both open ends. Cut small offcuts to wrap round elbows, valves and stop taps, leaving no bare pipe exposed - these spots are usually where dripping starts again first.

1 each · Self-adhesive lagging tape roll

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AB-08Cut humidity in the room, not just the pipeLagging alone won't fix a very steamy room. Run the extractor fan during and after cooking or showering, and open a window for 10-15 minutes afterwards. Avoid drying wet laundry on radiators near the pipe, as this adds extra moisture to the air.

AB-09Tidy up and check your workCollect foam offcuts and used tape and put them in general waste. Wipe down the area under the pipe, then check back after a few days - the pipe should stay dry even once the room warms up and gets humid again.

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