Dripping compression fitting
⚠️ Turn off the water supply before attempting any repairs.
A dripping compression fitting is one of the most common plumbing niggles homeowners encounter, and the good news is it's usually straightforward to fix. These leaks typically develop where copper pipe meets a compression nut — often under sinks, at stop taps, or on radiator connections — because the olive (a small brass ring inside the fitting) gradually loses its grip over time, especially after years of temperature fluctuations and slight pipe movement. Whether you're dealing with a persistent drip that's driving you mad or a leak that's started suddenly, this guide walks through the simple repair process that works in most cases. The beauty of compression fittings is that they're designed to be serviced without special tools, though patience and a gentle touch are essential. If you've already tried the basic fix or suspect corrosion damage inside the pipe, that's when it's worth calling a qualified plumber to avoid making matters worse.
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Most likely cause & what to check
Turn off the water supply. Gently tighten the compression nut by a quarter-turn only.
Do NOT over-tighten — this can crush the olive inside and make the leak worse.
If tightening doesn't stop it, dismantle the fitting, inspect the olive, and replace if damaged.
Wrap PTFE tape on threads before reassembling.
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Frequently asked questions
Can I just tighten the nut to stop a dripping compression fitting?
Often yes — many leaks respond well to a gentle quarter-turn tightening of the compression nut. However, the key word is gentle; over-tightening will crush the olive and make the leak worse, so resist the temptation to wrench it hard. If a quarter-turn doesn't work after 10 minutes, stop and move to dismantling and inspection instead.
What is the olive in a compression fitting, and why does it leak?
The olive is a soft brass or copper ring that sits inside the fitting and grips the copper pipe to create a watertight seal. Over time, it can become compressed, corroded, or slightly dislodged by vibration, causing water to weep past it. Replacing a damaged olive is inexpensive and usually fixes the problem permanently.
Do I need a special tool to dismantle and repair a compression fitting?
No — you'll only need two adjustable spanners or wrenches: one to hold the fitting body steady and one to turn the nut. Some people use a pipe wrench, but spanners are gentler on the chrome finish and are perfectly adequate for this job.
What's the difference between PTFE tape and plumber's tape, and which should I use?
They're the same thing — PTFE tape (polytetrafluoroethylene) is commonly called plumber's tape or thread seal tape and prevents leaks around threaded connections. When reassembling a compression fitting, wrap it clockwise around the male threads a few times before reconnecting, which creates an extra watertight barrier.