Why is water leaking under my bath?

The usual causes are a failed silicone seal, a leaking overflow or waste seal, a loose trap, or a leaking tap connection. When the leak appears tells you which is most likely.

Why does my bath only leak when I shower?

Water from the shower is getting behind the seal, screen or grout along the bath edge. Resealing properly usually cures it, but check the bath does not move when you stand in it.

How do I know if my bath overflow is leaking?

Fill the bath until water runs into the overflow, then check under the bath and on the ceiling below. If water appears only then, the overflow seal is the likely cause.

Can a leaking bath damage the ceiling below?

Yes. Water under a bath often shows up first as a stain on the ceiling underneath. Stop using the bath and deal with the leak before the ceiling is saturated.

Do I need to remove the bath to fix a leak?

Rarely. Most seal, waste, overflow and tap connection leaks can be fixed through the bath panel. The bath usually only comes out if it is cracked or needs better support.

Emergencies and water leaks guides →

Leaking bath: how to find where the water is escaping

A leaking bath is usually one of five things: the silicone seal where the bath meets the wall, the overflow, the waste and plug hole, the pipes feeding the taps, or a crack in the bath itself. The quickest way to tell them apart is timing. A leak that only appears when someone showers points to the seal or screen, one that appears as the bath drains points to the waste, one that only happens with a full bath points to the overflow, and a leak that carries on when nobody has used the bathroom points to a supply pipe that is under pressure all the time. Stop using the bath until you know, because water under a bath often shows up first as a stain on the ceiling below.

Loyal Plumbers · Updated 27 September 2026

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First, limit the damage

If water is coming through the ceiling underneath, treat that first. Keep clear of any sagging plaster, switch off a ceiling light below if water is near it, and put down containers. Our guide to a ceiling leaking water covers that situation in more detail.

Then stop using the bath and shower over it. If the leak continues even when the bath is not in use, the supply to the taps is the likely source. Many baths have small isolation valves on the hot and cold pipes behind the bath panel, which you can turn a quarter turn with a flat screwdriver. If you cannot find them, turn off the water at the stopcock.

Use the timing to find the source

The water you can see is rarely right under the fault. It can run along the floor, the joists or the underside of the bath for some distance before it drips. When the leak starts, and what you were doing at the time, is a far better clue than where the puddle is.

When a bath leaks and what that usually means
When the leak appears	Most likely source
Only while someone is showering over the bath	Silicone seal, bath screen seal or grout along the tiled edge
Only when the bath is filled high	Overflow seal behind the overflow cover
As the bath empties	Plug hole seal, waste pipe joint or trap under the bath
When the taps or mixer are running	Tap connections, mixer body or a shower hose
All the time, even when the bath is not used	Hot or cold supply pipe or a joint under the bath
Only when someone stands or sits in the bath	Bath flexing and breaking the seal, or a crack in the bath

A simple test you can do

If you can take off the bath panel safely, do so and have a torch ready. Many panels clip on or are held by a few screws; if yours is tiled in or sealed, leave it for the plumber. Dry everything you can reach under the bath with a towel, then work through these steps one at a time and look underneath after each.

Run the hot and cold taps into a jug or bucket held in the bath, so no water reaches the waste. Water underneath now means a supply or tap connection.
Put the plug in and fill the bath a few centimetres. Wait ten minutes. Water underneath means the plug hole seal.
Pull the plug and watch as it drains. Drips from the pipework under the plug hole mean the waste or trap.
Fill the bath until water runs into the overflow. Water behind or below the overflow means its seal.
Pull the plug, dry the bath edge and then run the shower along the sealed edge for a few minutes. Water appearing now means the seal, grout or screen.

Stop the test as soon as you find water, and do not refill the bath if the ceiling below is already wet. If there are electrical fittings under or near the bath, such as a whirlpool pump or underfloor heating connections, leave the panel on.

The silicone seal: the most common culprit

The seal between the bath and the wall takes a lot of punishment, especially with a shower over the bath. Once it lifts, cracks or goes mouldy, water from the shower runs behind it and down the wall, and it can travel a long way before anyone notices. Grout on the tiles above can let water in the same way.

Resealing is straightforward when done properly. The old silicone must be removed completely, the joint cleaned and dried, and the new bead applied with the bath filled with water so it is sitting at its lowest before the seal sets. Sealing an empty bath is a common reason new seals split within weeks. If the bath moves when you stand in it, the seal will keep failing until the bath is properly supported.

Overflow, waste and trap leaks

The overflow is connected to the waste by a flexible pipe, sealed behind the chrome cover with a rubber washer. Those washers harden and the connection can work loose, so the leak only shows when the water reaches that level. The plug hole has its own seal, and below that the trap and waste pipe have joints that can loosen or crack, particularly if the bath has been knocked or the pipe was fitted under strain.

Many of these parts can be resealed or replaced without taking the bath out, provided there is access from the panel side. Our guide to bath waste and overflow replacement explains what a proper repair involves and why good access matters.

Supply pipe and tap leaks

A leak on the hot or cold feed behind the bath is different, because it is under pressure and does not stop when the bath is empty. It can soak a floor and the ceiling below for weeks if the pipe is hidden. Signs include a stain below the bath that keeps spreading even when the room has not been used, and a water meter that keeps turning with every tap closed.

These leaks are often at a tap connector, an isolation valve or a joint on the pipework, and they are usually a quick repair once the panel is off. Where the pipe runs under the floor or into a wall, it may need tracing first with leak detection and repair.

Cracked or poorly supported baths

Acrylic baths are light and flexible, so they rely on their frame and feet to stop them moving. If the bath sinks slightly when filled or when someone gets in, that movement breaks the seal and strains the waste. Sometimes it cracks the bath itself, usually near the plug hole or where the feet sit.

Small cracks in acrylic can sometimes be repaired, but a bath that flexes needs its support sorting out first. A badly cracked bath, or a steel bath with a chipped and rusting base, usually has to be replaced, which is where our bathroom fitting service comes in.

Getting the leak fixed

Call if water is coming through a ceiling, if the leak continues when the bath is not being used, if you cannot get at the pipes, or if the leak is affecting a flat below. In a building with flats, a water leak between flats can involve your neighbours and a managing agent, and early contact makes that easier. Keep photos of any damage for your insurer.

Loyal Plumbers has 10 vans covering London and everywhere inside the M25, 24 hours a day. When you get in touch, tell us when the leak appears, whether there is a shower over the bath, whether the panel can be removed and whether water has reached a room below. Our call-out charge is £60, and the engineer explains what they have found and what the repair involves before starting.

Common questions

Why is water leaking under my bath?: The usual causes are a failed silicone seal, a leaking overflow or waste seal, a loose trap, or a leaking tap connection. When the leak appears tells you which is most likely.
Why does my bath only leak when I shower?: Water from the shower is getting behind the seal, screen or grout along the bath edge. Resealing properly usually cures it, but check the bath does not move when you stand in it.
How do I know if my bath overflow is leaking?: Fill the bath until water runs into the overflow, then check under the bath and on the ceiling below. If water appears only then, the overflow seal is the likely cause.
Can a leaking bath damage the ceiling below?: Yes. Water under a bath often shows up first as a stain on the ceiling underneath. Stop using the bath and deal with the leak before the ceiling is saturated.
Do I need to remove the bath to fix a leak?: Rarely. Most seal, waste, overflow and tap connection leaks can be fixed through the bath panel. The bath usually only comes out if it is cracked or needs better support.

Sources and further reading

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