Why is water leaking onto the floor outside my shower?
The three tests that separate spray escape from a seal failure from a tray or waste leak — done in an order that costs nothing before anything is taken apart.
- Difficulty
- beginner
- Time
- 1 hr
- Read
- 5 min
- Safety
- caution
Short answer
First establish whether it only happens with someone in the shower, which means spray escape rather than a leak. If it happens with the shower running and nobody in it, run three tests in order: shower on with the door shut, then a plugged tray full of standing water, then a jug down the waste alone. Each one isolates a different cause. Do not reseal anything until one of them has reproduced the leak.
Almost everybody resealing a shower is resealing the wrong joint. The bead is the visible thing, so it gets blamed, and new silicone hides a tray leak or a valve leak for a few weeks while the floor underneath keeps getting wet. The tests below cost nothing but time and they each isolate one cause, so at the end you know what you are fixing. The flowchart lays out the order.
Safety
What you'll need
- Kitchen roll or a dry cloth, to find where water actually appears
- A torch
- Something to plug the waste — a flat rubber plug or a wet cloth
- A jug
- A moisture meter, if you have one
Step by step
- Dry everything and find where the water first appears.Dry the floor completely and lay kitchen roll along the outside of the enclosure, at the door, at the wall joints and at the corner nearest the waste. Then use the shower normally. Whichever sheet wets first is where the water is arriving, and that is worth far more than a general impression that the floor is wet.
- Ask the splitting question: does it happen with nobody in it?Run the shower with the door properly closed and nobody inside for five minutes. If the floor stays dry, you do not have a leak — you have spray escaping past the door while someone is in there, which is a completely different problem.
- If it is spray escape, work through the four causes.The door seals or the drip strip are missing, hardened or the wrong profile; the door is not being fully closed; the head is aimed at the door or the opening; or a walk-in panel is too short for the tray. None of these is fixed by resealing the tray.
- Test 1 — shower running, door shut, nobody in it.If water appears now, watch the outside of the enclosure with a torch. Water tracking along the underside of the bottom rail, or seeping from a corner of the frame, means either the silicone at the tray-to-frame joint has failed, or the frame is filling internally because its drain holes have blocked. Frames are designed to let water out into the tray; when the small holes at the bottom of the track scale up, the frame fills and overflows outwards.
- Test 2 — plug the waste and stand water in the tray.With the shower switched off entirely, block the waste and fill the tray to a few centimetres. Leave it an hour with the floor dry and kitchen roll around it. Water appearing now means the tray-to-wall seal or the tray itself, and nothing to do with the shower or the door. This is the test that catches a cracked tray.
- Test 3 — jug down the waste, nothing else.With the tray dry, pour a jug of water slowly down the waste and watch underneath if you have any access. Water then is the waste flange, the trap, or the trap's connection to the waste pipe. This is also the test that catches a trap washer fitted the wrong way up.
- If none of the three reproduces it, look at the valve wall.A floor that is wet nearest the wall the shower valve is on, with all three tests clear, means the leak is behind the tiles at the valve body, the riser connection or a pipe joint in the wall. That needs the panel or the tiles opened up, and it is the point at which a plumber earns their fee.
- Check what the water has already done.Before repairing anything, press the floor around the shower and listen and feel for softness. Look at the ceiling in the room below. Wet chipboard swells and never recovers, and a repair that fixes the leak but leaves rotten floor under a tray is a repair that fails again in a year.
Common mistakes
- Resealing the tray-to-wall joint as the first move — It is the visible joint and it is the least likely cause. New silicone masks a tray or waste leak for a few weeks while the floor keeps getting wet.
- Assuming a dry bathroom floor means no leak — Water follows the fall of the floor and the line of the joists. A shower leak very often appears first as a stain on the ceiling below.
- Ignoring a tray that flexes underfoot — Movement is what breaks the seal in the first place. Resealing a moving tray buys a few months at most.
If it doesn't work
Water appears only at the door, only while someone showers
Cause: Spray escape past a worn or missing seal — Fix: Identify and replace the door seals, and fit a drip strip if there is none. Check the head is not aimed at the opening.
Water seeps from under the bottom rail after the shower has been running a while
Cause: Blocked drain holes in the enclosure's bottom track, so the frame fills up — Fix: Clear the small drain holes in the underside of the track with a piece of wire and flush the track. Then check the silicone at the tray-to-frame joint.
Standing water in a plugged tray leaks with the shower off
Cause: Failed tray-to-wall seal, or a cracked tray — Fix: Look for a crack with the tray dry and a torch held at a low angle. If the tray is sound, the wall seal has failed and needs cutting out fully and replacing — and if the tray moves underfoot, fix the support first or it will fail again.
Water only after pouring down the waste
Cause: Waste flange seal, trap joint or trap washer — Fix: Get access to the trap, dismantle the joint, check the washer orientation and the pipe is fully home, and rebuild hand-tight.
Damp only appears in the room below and never on the bathroom floor
Cause: The leak is running along a joist and dropping away from the shower — Fix: This is common and it makes the bathroom look innocent. Work the three tests anyway, and look at the ceiling below during each one rather than at the bathroom floor.