Bath, Shower Or Basin Draining Slowly

What's happening?

WaterSafe lists the causes of a slow shower drain: hair that clings to the pipe walls, soap residue that mixes with minerals to form a sticky film that traps hair, hard water deposits and small objects that fall in. A bath and a basin are the same with different parts: the bath waste and overflow, and the basin pop-up waste and overflow channel. A bath or shower that is slow while the sink is fine points to its own trap or waste. A bath, shower and basin all slow, or gurgling when a toilet is flushed, points to the drain. A persistent foul smell or repeated blockages can mean a problem with the main drain.

What usually causes it?

• Hair and soap scum around the grid, pop-up waste and trap
• Hard water deposits and scale narrowing the waste pipe
• A trap that has filled with debris
• Small objects dropped into the waste outlet
• A blockage in the shared drain, so every bathroom fitting drains slowly

Is it dangerous?

No. Standing water can give off an unpleasant smell. Chemical drain cleaners should be used sparingly: WaterSafe warns that frequent use can corrode pipes. Do not use boiling water on PVC pipes.

Can I fix it myself?

Lift the grid or pop-up waste with a screwdriver, shine a torch in and pull out the hair with gloved fingers or a bent coat hanger. Pour very hot but not boiling water down to loosen soap scum. WaterSafe describes a plunger for a shower with enough water to cover its base. Unscrew a bath or basin trap, over a bowl, and clean it. Fit a hair catcher. If the blockage returns within days, or the basin, bath and shower are all slow, stop and call.

When should you call a drainage engineer?

Call a drainage engineer when more than one fitting is slow, when the bath or shower gurgles when the toilet is flushed, when there is a persistent foul smell, or when clearing the waste only works for a few days.

What will the drainage engineer actually do?

• Check which fittings are slow and whether the outside chamber or the main drain is affected
• Clear the trap and waste with a drain machine, or jet the branch
• Camera the drain if the problem returns, to look for a sag, a collapse or roots
• Advise on hair catchers and cleaning

Who fixes this

• Blocked toilet and sink
• Blocked drain clearing

What it usually costs

Drain Unblocking Cost

Priced on survey

Questions people ask

Sources & References

1. WaterSafe: how to clear a clogged shower drain
2. WaterSafe: how to tell if your outside drain is blocked