Domakihub Replace a Bathroom Sink Siphon Without Calling a Plumber
A leaking bottle trap or P-trap is a quick fix most homeowners can handle in under an hour.
Reviewed by Domakihub home & decor pros · 2026-06-23 · 4 min read
A dripping under-basin siphon is one of the most common plumbing issues in Greek homes, holiday rentals, and hotel bathrooms — and one of the easiest to fix yourself. Whether you have a compact bottle trap tucked inside a vanity unit or an exposed P-trap beneath a pedestal basin, replacing it takes no specialist tools and no trade licence. Watch the video above for a clear visual walkthrough, then follow the steps below to complete the job with confidence.
Bottle Trap or P-Trap: Which Do You Have?
The siphon beneath your basin comes in two common forms. A bottle trap is a slim, cylindrical unit that sits close to the wall and is the default choice in most modern Greek bathrooms where cabinet space is tight. A P-trap (or U-bend) is the traditional S-shaped pipe more common in older properties and commercial settings. Both work on the same principle — holding a water seal that blocks drain odours from rising into the room — and both are replaced using the same basic process.
The most telling sign that your siphon needs replacing rather than tightening is visible cracking in the plastic body, persistent drips from the joints even after hand-tightening, or a foul smell that suggests the water seal is no longer holding. In holiday rental properties, these problems tend to appear after long vacancy periods when water in the trap has evaporated and tenants have made do with temporary fixes.
What You Need Before You Start
Pick up a replacement siphon that matches your existing outlet diameter — 32 mm and 40 mm are the two standard sizes sold in Greek hardware shops (χρωματοπωλεία) and plumbing merchants. Bring the old unit with you if possible, or photograph it alongside a ruler. You will also need a bucket or small bowl, an adjustable spanner or slip-joint pliers, and PTFE tape (teflon tape) for the threaded connections. A small torch helps when working inside a dark cabinet.
Avoid buying the cheapest single-use plastic units if the property sees heavy use. Mid-range polypropylene traps from brands such as McAlpine or Viega last significantly longer and are widely available in Greece through plumbing wholesalers and larger DIY chains.
How to Replace Your Basin Siphon: 5 Steps
- 1
Turn Off the Water and Clear the Cabinet
You do not need to isolate the water supply to replace a siphon — the trap sits on the drain side, not the supply side. However, turn off the tap above to avoid anyone running water mid-job. Remove everything from inside the vanity unit and place a bucket directly beneath the existing trap to catch residual water.
- 2
Unscrew and Remove the Old Trap
Unscrew the slip-joint nut connecting the trap to the basin waste outlet (the vertical stub coming down from the plug hole) and the nut connecting it to the wall drain spigot. On a bottle trap, there is usually also a cleaning cap at the base — unscrew it to let the standing water drain into your bucket before you detach the unit fully. Pull the old trap free and discard it.
- 3
Clean the Connection Points
Wipe the basin waste outlet and the wall drain spigot with a damp cloth. Remove any old sealant residue or limescale build-up from the threads. This step is quick but important: a clean mating surface is what prevents the new joints from weeping. If you see any corrosion on the wall spigot itself, apply a thin wrap of PTFE tape over the threads before fitting the new trap.
- 4
Fit and Hand-Tighten the New Siphon
Offer the new siphon up and thread the slip-joint nuts finger-tight first, starting at the basin waste outlet and working toward the wall. Check that the trap body is sitting level and that flexible sections (if your replacement has them) are not kinked. Once everything is aligned correctly, give each nut a quarter-turn with pliers — firm, not forceful. Over-tightening plastic fittings cracks them immediately or within a few weeks.
- 5
Test and Check for Leaks
Run the tap steadily for 30 seconds, then crouch down and inspect every joint while the water is still flowing. Dry each connection with a piece of kitchen paper and check for damp spots. Fill the basin fully and release the plug to stress-test the waste flow. If any joint weeps, tighten it by small increments until the drip stops. A correctly fitted siphon should be completely dry within one minute of the water draining.
Rather have a pro handle it?
Get a vetted plumbing pro in your city — one number, booked in EN/EL/DE.
FAQ
- How do I know whether to buy a 32 mm or 40 mm replacement trap?
- Measure the outer diameter of the plastic stub that protrudes downward from your basin plug hole. In most Greek bathroom basins the waste outlet is 32 mm; 40 mm is more common in kitchen sinks and older pedestal basins. If in doubt, remove the old trap and take it to the hardware shop — the size is usually stamped on the nut.
- My new trap still drips at the wall connection. What am I missing?
- The wall spigot in older Greek properties is often slightly out of round or corroded. Wrap two or three layers of PTFE tape clockwise around the spigot threads, then refit the slip-joint nut. If the spigot is a push-fit type rather than threaded, make sure the rubber o-ring inside the trap socket is seated flat and undamaged — sometimes it flips during fitting.
- Can I leave the basin out of service overnight if I cannot finish the job?
- Yes, but block the open drain hole with a rag or an old plug to prevent sewer gases from entering the room. In holiday rentals and hotels, also tape a note to the mirror so guests do not use that basin. Siphon replacement is almost always a single-session job, so aim to complete it in one go rather than leaving the drain open.