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Fix multiple small kitchen leaks (U-bend, loose tap, pipe)

  • Writer: Robert Costart
    Robert Costart
  • May 29
  • 3 min read

Updated: Jun 4



📝 Overview


  • Stopping minor water leaks under a kitchen sink: a dripping plastic U-bend (P-trap), seepage from a wobbling mixer tap base, and a weeping 15 mm copper pipe compression joint.

  • Skill level: 3 / 5 (competent DIYer, basic plumbing and patience).

  • Typical duration: 2–3 h total hands-on.




⚠️ Safety First


  1. Isolate hot and cold supplies at the service valves or main stop-cock before working on any tap or pipe.

  2. Place a sizeable bowl or bucket beneath the trap before opening it—dirty waste water can contain bacteria.

  3. Wear cut-resistant gloves; plastic trap edges, brass olives and stainless sink rims are sharp.

  4. Use eye protection when trimming pipe or tipping trap contents—grit and splashes travel fast.

  5. Disconnect kitchen electrics (e.g. dishwasher plug, waste-disposal spur) where leaks may reach sockets.




🧰 Tools & Materials

Item

Purpose

Adjustable spanner set

Tighten compression nuts on pipe and tap tails

Basin wrench or 11 mm–12 mm monobloc box spanner

Reach the tap’s retaining/back-nut

Pipe cutter & deburr tool

Trim copper and prepare fresh olive seating

Spare 15 mm brass olives & compression nut

Cure weeping pipe joint

PTFE tape

Seal male threads where needed

Replacement P-trap washers / complete trap

Stop U-bend drips

Silicone grease

Lube trap washers & tap gaskets for long life

Plumber’s putty or non-setting sanitary silicone

Reseal tap base to sink

Bucket, old towels, torch

Catch water, keep area lit and tidy


📋 Step-by-Step



1. Locate each leak precisely


  • Action: Dry all suspect joints, run the tap, and watch for the first bead of water.

    • Why: Confirms which component—and which sub-joint—needs attention.

    • Pro-tip: Wrap tissue around joints; damp patches reveal even pin-hole weeps.



2. Fix the U-bend (P-trap) leak


  1. Loosen & clean

    • Action: Unscrew the slip nuts hand-tight (use gloves for grip) and lower the trap into a bucket.

    • Why: Removes sludge and lets you inspect sealing washers.


  2. Replace or flip washers

    • Action: Inspect conical washers; if nicked or flattened, fit new ones (bevel towards the pipe). If sound, flip them for a fresh sealing edge.

    • Why: A fresh edge compresses better and stops drips.

    • Pro-tip: Smear washers with silicone grease before reassembly.


  3. Reassemble & test

    • Action: Hand-tighten slip nuts, then give an extra quarter-turn—plastic threads crack if over-wrenched. Run the sink full-flow for 60 s and look for drips.

    • Why: Confirms a watertight waste before tackling other leaks.



3. Secure the loose, leaking tap base


  1. Tighten the retaining nut

    • Action: From inside the cupboard, use a basin wrench or box spanner to snug up the tap’s back-nut while a helper keeps the tap centred above.

    • Why: Wobble stresses flexi tails and lets water track under the gasket.


  2. Renew the base seal (if still weeping)

    • Action: Isolate water, disconnect flexi tails, remove the tap, peel off the old rubber gasket. Clean the sink deck with methylated spirits, seat the tap on a new rubber gasket or a thin bead of non-setting sanitary silicone, then refit and retighten.

    • Why: Stops capillary leaks around the tap hole.

    • Pro-tip: Lightly grease the gasket so limescale can’t glue it down in future.



4. Repair the weeping compression pipe joint


  1. Open joint & inspect

    • Action: Hold the valve body with one spanner; undo the compression nut with another. Slide off the nut and olive.

    • Why: Lets you see if the olive is distorted or the pipe scored.


  2. Refresh the seal

    • Action: Cut 10 mm off the pipe end, deburr, slide on a new olive and the nut. Apply two wraps of PTFE tape on the male thread, then tighten firmly while counter-holding the valve.

    • Why: Fresh pipe and olive give a perfect metal-to-metal seal.

    • Pro-tip: A tiny smear of silicone grease on the olive helps it seat without ripping.


  3. Pressurise & check

    • Action: Open isolation valves slowly; dab the joint with tissue while the tap runs.

    • Why: Ensures the compression joint is now bone-dry.



5. Final inspection


  • Action: With all three fixes complete, run hot and cold, fill and flush the sink, and check the cupboard base, pipes and trap for 5 minutes.

    • Why: Confirms nothing was disturbed during the sequence of repairs.




🔍 Completion Checks


  • Trap slip-nuts dry to touch after sink has been left full for a minute.

  • Tap base rigid; no moisture around the gasket edge or flexi-tail unions.

  • Compression joint tissue-dry after 10 min at normal mains pressure.

  • Cupboard floor remains dry overnight.




👷‍♂️ When to call a pro instead


If any slip nut or brass back-nut is seized solid, the copper pipe shows pin-hole corrosion, or tightening the tap causes flexi tails to kink and leak, a plumber with replacement pipework, freeze-plug gear and specialist basin sockets can resolve the issues quickly and restore full water-regulation compliance.

 
 
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