Why will my bath pop-up plug not open or hold water?

A basin pop-up is worked by a rod behind the tap. A bath pop-up cannot be — there is nothing to reach through — so it is worked from the overflow plate instead, either by a rotating cam turning a cable that runs down the overflow hose, or by a lever mechanism inside the overflow. That cable is the part that goes out of adjustment and the part that seizes, and hair collecting on the plug stem is what stops it seating.

What you'll need

• Rubber gloves
• A screwdriver for the overflow plate
• A flexible barbed drain tool
• Silicone grease

Step by step

1. Work out how yours operates.A knurled ring or knob on the overflow plate that you twist is a cable or cam pop-up. A plug you push down and it clicks is a click-clack, which has no linkage at all and is a different repair. A small lever on the overflow plate is an older lever-and-rod type.
2. Take the plug out first.Most bath pop-up plugs either unscrew from the stem or lift out with a firm straight pull once the mechanism is in the open position. Look at the underside of the plug as it comes out — the hair is usually there, wound round the stem.
3. Clear the hair properly.Pull what is visible out with gloved fingers, then feed a flexible barbed drain tool down and draw it back slowly. Clear the overflow connection too, using the same tool through the overflow hole with the plate off.
4. Check the plug seal.There is a rubber seal on the underside rim of the plug. If it is hardened, distorted or has a nick in it, it will not hold water however well the mechanism works. Seals are sold separately and are cheap.
5. Clean the seat in the waste.Limescale and soap on the machined seat inside the waste flange stops a good plug sealing. Work round it with an old toothbrush and descaler, then rinse.
6. Adjust the cable or the linkage.With the overflow plate off, you will find either an adjustable ferrule on the cable end or a threaded stem on the plug. Set it so that with the control knob at the fully closed position, the plug just seats without the mechanism straining, and with the knob fully open the plug lifts enough for water to run past freely. Both ends of the travel need checking, not just one.
7. Grease the moving parts.A smear of silicone grease on the plug stem, the cam and the cable end keeps it moving and stops hair binding to it as readily. Do not use oil or petroleum grease — it perishes rubber seals.
8. Test with the bath actually full.Fill it to a normal level and leave it for twenty minutes with a mark on the water line. A plug that seats but seeps loses a few centimetres in that time and needs its seal replacing rather than more adjustment.

Tips

• Fit a hair catcher over the plughole and you will do this job once rather than annually.
• If the mechanism is seized and the parts are unavailable — common on older or own-brand kits — a chain plug that simply sits in the seat is a perfectly good and instant substitute.
• Clean the plug and stem every few months as a habit. It takes a minute with the plug lifted out and it prevents both the slow drain and the failure to seal.

If it doesn't work