Stopcock or stop tap is leaking
Check the steps below first — if you're not confident, get it fixed safely today.
Post a job — we'll find you an engineer →⚠️ If the leak is from the main house stopcock and you cannot stop it, turn off at the external stopcock (in a box near your boundary) before attempting any repair.
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Most likely cause & what to check
A stopcock can leak from two places: the gland (the seal around the valve spindle, visible when the valve is partly open), or from the body/connection joints (compression fittings or solder joints either side of the valve body).
For a gland leak (drip from around the valve handle/spindle area): try tightening the gland nut clockwise — it is the nut immediately below the handle. Use a spanner to turn it one flat at a time. This compresses the packing material inside and often stops the leak without any disassembly.
If tightening the gland nut does not stop the leak, the gland packing needs repacking. Turn the water off upstream. Remove the valve handle and unscrew the gland nut. Remove the old packing (PTFE ribbon, graphite rope, or fibre). Repack with fresh PTFE tape wound tightly around the spindle, or use PTFE fibre packing (available from plumbers merchants, under £5). Refit the gland nut and turn on.
For a leak from the compression joints either side of the valve: try tightening the compression nuts slightly (quarter turn). If leaking continues, the compression fitting needs to be remade — this requires draining the section of pipe, disassembling the fitting, possibly replacing the olive, and retightening.
If the stopcock is old, corroded, or has a stem that is difficult to turn, replacement is often more cost-effective than repair. Modern lever-handle ball valves (£8–£20) are far more reliable than old gate-type stopcocks and are easier to operate in an emergency.
When refitting any stopcock, ensure the valve is installed in the correct flow direction — an arrow on the body indicates the direction of flow. A stopcock fitted backwards will not work correctly.
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