Start at the waste, not the drain cleaner
Lift the waste cover, most unscrew or lever out, and look. In a shower tray the trap sits directly below and is often removable by hand. The blockage is usually a compacted mass of hair sitting on the trap seal, and a pair of gloves and a bent piece of wire will pull most of it out.
A drain snake or a cheap plastic hair removal strip from a hardware shop reaches further and is far more effective than pouring anything down the hole. Once cleared, flush a kettle of hot, not boiling, water through to move the residue. Boiling water can distort plastic waste fittings and damage seals, so keep it just off the boil.
Why chemical cleaners are a poor first choice
Caustic drain cleaners attack the soap film but do very little to a solid hair mass, and they sit against plastic pipework and rubber seals while they work. On older push fit and compression waste systems, repeated use is a genuine cause of weeping joints, which then turns a slow drain into a leak.
If you have already poured cleaner down and it has not worked, tell whoever comes out. Caustic liquid sitting in a trap is a hazard when a joint gets opened, and it changes how the job is approached.
When it is not the trap
If the trap is clean and the water still backs up, look wider. A waste pipe with too little fall will drain sluggishly forever, and this is common where a tray or wet room gully was fitted into a limited floor depth. Long horizontal runs with a dip in them collect residue at the low point.
If other fittings in the house are slow at the same time, or if water gurgles in the basin when the shower drains, the issue is likely in the branch pipe or the soil stack rather than the shower. Gurgling in particular suggests air is being pulled through a trap, which points at a partial blockage or a venting problem further down.
Wet rooms and linear drains
Wet room gullies and linear channel drains catch far more debris than a standard tray waste because the whole floor drains through them. Most have a removable basket or a lift out trap section designed to be cleaned, and many people simply never realise it comes out.
Clean it monthly and a wet room drain rarely gives trouble. Leave it a couple of years and the trap fills with a compacted layer that needs breaking out. If the drain was fitted so the floor falls unevenly towards it, water will also pool away from the outlet, and that is a tiling issue rather than a blockage.
When to call a plumber
Call if the shower backs up when another fitting is used, if water rises rather than drains slowly, if there is a persistent drain smell after clearing, or if you have cleared the trap twice in a few months. Repeat blockages usually mean poor fall or a partial obstruction downstream, and clearing the trap again just resets the clock.
We clear and rebuild shower and wet room wastes across Gloucester, Cheltenham, Tewkesbury, Stroud, Stonehouse, Malvern, Ledbury, Newent and Ross-on-Wye. Mention through the enquiry form whether anything else in the house is slow, because that decides whether we are looking at the shower or the pipework behind it.