How To Clear A Blocked Trap


When a bath or basin becomes blocked it is usually the trap underneath that is at fault. Loose hairs are the most common cause of trap blockages and if conventional plunging fails to shift them you have no choke but to remove the offending material by hand.

How you do this depends on the type of trap installed. On a bath, you will have to unscrew and remove the panelling to gain access.

How To Clear A Blocked TrapOld style U trap:

These are generally of brass or lead, and must be handled with care to avoid damage.

1. Place a bowl underneath the trap and a piece of wood in the U part. Holding the wood in one hand, to counteract the turning force, use a wrench to unscrew the clearing eye which you will find at the base of the trap.

2. Hook out any debris remaining in the trap with stiff wire. Then clean the thread of the clearing eye and wrap a few turns of PTFE joint tape around it. Replace the eye, turning it a fraction over hand tight.

Plastic U trap:

In this case you must dismantle the entire trap.

3. Unscrew the locknuts either side of the trap by hand. Wrapped around a cloth. If they won’t budge, boiling water should shift them.

4. When you reassemble the trap, a few turns of PTFE tape around the locknut threads will prevent leaks.

Bottle traps:

These are the simplest of all to clear.

5. Hold the waste pipe in one hand and unscrew the cover with the other, wrapped in cloth.

6. Having allowed the debris to fall out into your waiting bowl.

Poke some stiff wire into the waste pipe to clear any residue then refit the cover. Again, a little PTFE tape wrapped around the cover thread will prevent leaks and save you having to tighten the cover too hard. Run the taps to check the repair.

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