Why Is My Shower Tray Leaking?

The most common causes of a leaking shower tray, in rough order of likelihood, are: failed sealant around the tray edges, a leaking waste/trap connection underneath, or a cracked tray — each has a different fix, so working out which one you have first saves time and money.

How to narrow down the cause

• Check the sealant line first. Run your finger along the joint between the tray and the tiles/wall — if it's cracked, gappy, or has visible mould, this is a strong candidate and the cheapest fix.
• Check for water only when the shower's running, not when it's just wet from splashing. If leaking only happens during active use, it points to the waste connection or a tray joint failing under running water rather than standing water.
• Look for visible cracks in the tray itself, particularly on acrylic trays, which can crack under weight if not properly supported underneath.
• Check underneath if you have access (via a removable panel or from below if it's a first-floor bathroom) — a leaking trap or waste pipe joint is often visible as damp or staining directly under the tray.

Fixing failed sealant

If sealant is the cause, this is a realistic DIY fix — remove the old sealant completely, clean and dry the joint, then reseal with sanitary silicone. See our guide to bathroom sealant replacement for the full process. This alone resolves a large share of shower tray "leaks" that are actually just sealant failure, not a fault with the tray or plumbing.

Fixing a waste connection leak

A leaking waste connection under the tray usually means the trap or waste pipe joint has loosened or the seal has perished. This typically needs partial or full access to the trap — straightforward for a plumber if there's a removable access panel, more involved if the tray needs lifting. This is generally not a DIY job unless you're confident working with plumbing fittings, since getting it wrong risks a bigger leak.

Fixing a cracked tray

A cracked tray, particularly a lightweight acrylic one, usually needs replacing rather than repairing — temporary sealant patches over a crack tend to fail again quickly. This is a bigger job requiring the shower enclosure to come apart, tiling to be disturbed, and the new tray properly supported (a rigid tray support, not just resting on the subfloor) to prevent the same problem recurring.

Common mistakes

• Only resealing the visible top edge without checking underneath — if the real leak is the waste connection, resealing the top won't fix it and the damage continues unseen.
• Ignoring a small leak because it seems minor — water getting into a floor void, especially in an upstairs bathroom, can cause ceiling damage below before it's obvious from inside the bathroom itself.
• Fitting a new tray without proper support, leading to flexing, cracking, and repeat sealant failure.

When to call a professional

If you've checked the sealant and it looks fine, or you've resealed it and the leak persists, it's time to call a plumber rather than keep guessing. A plumber can pressure-test the waste connection and inspect the tray from underneath if access allows, which is the reliable way to confirm whether the trap or waste pipe is the actual source — trying to diagnose this by eye alone from inside the shower enclosure is often inconclusive.

Preventing repeat leaks

Once a leak is fixed, a few habits reduce the chance of it recurring: avoid standing directly on the tray edges where possible (they're typically the least supported part), clean sealant lines regularly rather than letting grime build up and mask early cracking, and address any flex or movement in the tray promptly rather than living with it, since flexing accelerates sealant and joint failure over time.

If you're noticing damp or a smell rather than visible water, our guide to bathroom drain smells covers a related but different set of causes.

What a plumber call-out typically costs

If you're not confident diagnosing the leak yourself, a plumber's call-out to investigate a shower tray leak typically costs £60-£120 for the initial visit and diagnosis in most parts of the UK, with the actual repair priced separately once the cause is confirmed — resealing is usually the cheapest fix at the labour end, while lifting and replacing a tray is a bigger job, often £300-£600 including making good the surrounding tiling.

Enclosure type affects access

How easy a shower is to investigate and repair depends partly on the enclosure type. A framed enclosure with removable panels generally gives better access to the tray edges and waste than a fully tiled-in, frameless glass installation, where reaching the sealant or waste connection can mean more disruption. If you're planning a new shower installation and suspect you might need to service it in future, it's worth discussing access with your fitter at the planning stage.