Recognising leaks from shower drains
The shower drain is a common — but hard to find — source of leaks. The water seeps away slowly and often only appears a floor below. Here you can read the signs and how to trace the real cause.
A leaking shower drain is deceptive: there's no puddle of water, but with each shower a little moisture seeps away beneath the tiles. Over time this causes a damp patch on the ceiling below, loose tiles or a musty smell. Early detection prevents major damage.
How to recognise it
One or more of these? Then the shower drain is a suspect.
Three common causes
With a leaking shower drain, the problem is usually in one of these points. With leak detection we determine which one — without breaking open the entire bathroom.
- The drain/trap itself — a poor connection or crack under the shower drain.
- The sealant and grout seams — water penetrates the structure along worn sealant.
- The waterproof layer — damaged sealing under the tiles.
Without demolishing everything
Our approach keeps your bathroom intact:
- Moisture measurement identifies the wettest point.
- A targeted (water) test confirms the drain as the source.
- Only then, and only where necessary, carry out targeted repairs.
How to check the shower drain yourself
What you can safely do, what you'd better leave and what the professional work involves.
Before you call anyone, you can already find out a lot with a few simple checks. You don't break anything open and you help the plumber later on, because you already know when the moisture appears.
What you can safely do yourself
- Feel the sealant joints. Press your finger on the sealant along the wall, the shower tray and around the shower drain. If the sealant is hard, cracked or coming loose, water can run behind it.
- Check the grout. Soft, washed-out or darkly discoloured grout in the shower floor lets moisture through to the substrate.
- Clean the drain. Many shower drains have a removable insert. Remove hair and soap residue and put everything back straight and firmly. A crookedly replaced insert can itself cause a leak.
- Do a simple test. Do not use the shower for a few days and see if the damp patch underneath becomes drier. Then shower again and watch whether the patch returns. This way you can see if the moisture is connected to showering.
- Check the water meter. Turn off all taps and see if the meter stops. If it keeps running, a pressurised water pipe is probably leaking and not (just) the drain.
What you'd better not do
Don't apply new sealant over old, mouldy sealant. It adheres poorly and only hides the problem. Also don't remove tiles yourself or drill into the floor just to have a look. There's often a waterproof layer beneath the tiles. If you damage it, the repair becomes much bigger.
When a tradesman is needed
Does the patch keep coming back after you've checked the sealant and drain? Is the ceiling below wet, or does it smell musty under the bathroom? Then it's time for targeted investigation. If you live in a flat where water can come down to the neighbours, don't wait too long.
What the professional work involves
The plumber first measures with a moisture meter where the substrate is wettest. This is often followed by a targeted test: first water only in the drain, then only over the tiles and sealant seams. This shows which part is leaking. If the leak is in the connection of the shower drain to the waste pipe, it is usually renewed locally. If it's sealant or grout, these are removed and reapplied. If the waterproof layer itself is damaged, we first discuss honestly what is needed before anything is opened up. Read more about our approach to leak detection without breaking.
Related services
Need help? View the related service or call us directly.
Good to know
Short answers to questions we're often asked.
Often not. By first tracing precisely where the leak is, we can repair locally in many cases. Only with a truly worn seal or a thorough renovation is more work needed — we discuss that honestly beforehand.
A drain leak usually only produces moisture after use (showering), while a pipe under pressure leaks continuously. With moisture and pressure measurements, we make the distinction clear.
The sooner the better. Moisture under the tiles further damages the structure and the waterproofing, and causes mould. Early detection keeps the repair small.
Need help in The Hague or the Randstad?
Feel free to call us for advice or an appointment. In emergencies we're available 24/7.
Read also: Shower drain blocked · Sewer smell in the house