How to Fix a Leaking Compression Fitting — Trade Method
A compression fitting leaks for one of three reasons: nut not tight, olive damaged, or pipe out of round. Here is the trade fix for each.
Step-by-step method
1. Tighten the nut a quarter turn
Two spanners: one on the nut, one holding the fitting body. Turn 15° at a time — never gorilla-tighten as it crushes the olive.
2. Add jointing compound
If still weeping, isolate water, undo nut, apply Boss White or Loctite 55 to the olive, reassemble.
3. Replace the olive
If tightening doesn't seal, the olive is deformed. Cut it off (or split with a hacksaw carefully), slide a new one on, reassemble.
4. Check pipe roundness
If pipe was crushed by pipe clamps, cut back 25mm to fresh round pipe. Any oval section cannot seal a compression joint.
Frequently asked questions
Can I use PTFE tape on a compression fitting?+
Not on the olive — it goes on the thread only if you're using it as a backup. The olive itself needs jointing compound or nothing.
Compression vs solder joints?+
Compression is serviceable (undoable). Solder is more compact and permanent. Both are WRAS-approved for potable water.