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What are the most common reasons a shower leaks from the bottom?

Water on the bathroom floor, a damp skirting board, or a stain creeping across the hallway carpet. If you’ve spotted one of these, your shower is probably leaking from the bottom. The good news? Most of the time the culprit is a seal you can see, not something buried in the walls.

A shower that leaks from the bottom is almost always losing water in one of six places. The usual suspects are the silicone where the floor meets the wall, the seal under the shower screen, and cracked grout. Less often, it’s water pooling on a flat floor, the floor waste, or a failed membrane or pipe. The first three are usually fixed with a proper reseal.

This guide walks through each cause, a simple way to work out which one you’ve got, and when it’s time to call someone in. If you already know you need help, our shower leak repair service covers homes across Melbourne.

Key Takeaways – Most leaks at the base of a shower start at a failed silicone joint, the screen seal or cracked grout. – Queensland’s building regulator found residential bathroom warranty claims in 2024–25 averaged almost $25,000 to fix (QBCC, 2026). – Catching a leak while it’s still a seal problem is far cheaper than repairing the damage behind the tiles.

What are the most common reasons a shower leaks from the bottom?

Victoria’s Building and Plumbing Commission says sealants in wet areas must be waterproof, flexible, mould resistant and compatible with the materials around them (BPC, Waterproofing of wet areas). When any one of those qualities fails, water gets past. These are the six places it usually escapes.

1. Failed silicone where the floor meets the wall

This is the big one. The joint between the shower floor and the wall tiles moves slightly every time the building expands, contracts or settles. Over time the silicone loses grip, splits or shrinks away from the tile. Water runs down the wall, slips behind the silicone and finds its way under the tiles.

2. A broken seal under the shower screen

Look at where the glass or frame meets the shower base or hob. If that seal has lifted, water tracks straight under it and onto the bathroom floor. Framed screens often have small gaps or weep holes on the inside, so water in the track drains back into the shower. If someone has siliconed over those, water sits in the track and spills out the wrong side.

3. Cracked or missing grout

Grout isn’t waterproof on its own. It’s porous, and once it cracks or crumbles it lets water soak straight through to the bedding underneath. A few hairline cracks near the floor are enough to start a slow leak.

4. Water pooling instead of draining

Shower floors in Victoria have to fall towards the waste at a gradient between 1:80 and 1:50 (BPC). If the floor is too flat, or has a dip, water sits in corners and keeps testing every joint it touches. Watch where the water collects after a shower. That’s often where the leak starts.

5. A leaking floor waste

The waste is where the floor membrane, the tiles and the drain all meet. If the seal around the grate or the puddle flange underneath has failed, water escapes before it ever reaches the pipe. Hair and soap build-up that slows drainage makes it worse.

6. A failed membrane or hidden pipe leak

Behind the tiles sits a waterproof membrane. The National Construction Code requires the walls of the shower area to be waterproofed to at least 1800 mm above the floor (NCC 2022, Housing Provisions Part 10.2). If that membrane has failed, or a pipe in the wall is leaking, resealing alone won’t fix it.

The BPC’s guidance on wet areas is clear that every sealant in a shower has to stay waterproof, flexible and mould resistant to do its job. In practice, the silicone joints are the first line of defence. The membrane behind the tiles is the last. A leak that’s caught at the silicone stage is usually a same-day fix.

How can you tell where the leak is coming from?

The BPC notes that a shower floor must fall to the waste at between 1:80 and 1:50, so water that pools tells you something (BPC). You can narrow down the source yourself in about half an hour, with nothing more than a towel and a hand-held shower head. 123456 1 Floor-to-wall silicone 2 Screen seal 3 Cracked grout 4 Pooling water 5 Floor waste 6 Membrane or pipe Points 1–3: usually a reseal or regrout. Points 5–6: may need a plumber or waterproofer. The six places a shower usually leaks from the bottom. Illustration: Opal Caulking Services.

Start with everything dry. Then test one area at a time, for about ten minutes each, and check outside the shower and any room or ceiling below after each test.

  1. Spray the glass and screen seal only. Keep water off the floor joints. If the floor outside gets wet, it’s the screen seal.
  2. Run water down the walls only. Aim at the tiles, not the floor. A leak now points to the wall-to-floor silicone or wall grout.
  3. Run water straight into the waste. If water appears only now, the waste seal is the likely problem.
  4. Check your water meter. Turn off every tap in the house and note the reading. If it moves over an hour, there’s a pressurised pipe leak and you need a plumber.

Is it ever this tidy? Not always. Water can travel a long way along a slab before it shows up. But this test usually tells you whether you’re dealing with a seal problem or a plumbing one.

Is it a reseal job or something bigger?

The QBCC lists a persistent musty smell or mould growth as one of the most common early signs of waterproofing failure. It often points to moisture trapped behind walls or floors (QBCC, Industry Snapshot Top 10 defects: Waterproofing, 2026). The signs below help you judge how far the water has gone.

What you seeWhat it usually meansWho to call
Gaps, splits or peeling silicone, water on the floor after showersFailed silicone or screen sealA caulking specialist
Cracked or crumbling grout near the floorWater getting through to the beddingA caulking or regrouting specialist
Peeling or bubbling paint on the wall outside the showerWater has travelled through the wallCaulking specialist first, then a waterproofer if it persists
Loose or drummy tiles, white chalky residueLong-term moisture under the tilesWaterproofer
Water meter moving with all taps offPressurised pipe leakLicensed plumber

Here’s the part most people miss. The silicone and grout aren’t the waterproofing; the membrane behind them is. Their job is to stop water reaching the membrane in the first place. Every week a failed joint is left alone, the membrane takes water it was never meant to handle every day. Resealing early is less about the joint and more about protecting what’s behind it.

What does a shower leak cost if you leave it?

In 2024–25, each residential bathroom claim finalised under the Queensland Home Warranty Scheme averaged almost $25,000 in rectification costs (QBCC). Those figures are from Queensland, but the building work and the damage are the same in Melbourne.

That cost comes from what slow leaks do over months: rotting timber framing, swollen skirting boards and vanities, damaged plaster in the next room, and mould. A full bathroom strip-out to replace a membrane is a very different job from resealing a joint.

A leaking shower rarely gets cheaper with time. The joint that takes a few hours to reseal this month is the same one that soaks the wall framing next year. If you’re weighing up whether to wait, that’s the trade-off.

For a sense of what a reseal costs instead, see our guide on how much it costs to caulk a bathroom in Melbourne.

What we check on a shower leak call-out

When we look at a leaking shower, we work from the outside in. We check every silicone joint for adhesion, not just appearance, because silicone can look fine and still have let go of the tile. We look at the screen seal and weep holes, run water at each zone, and check the grout lines nearest the floor.

If it’s a seal or grout problem, we remove the old silicone completely, clean and dry the joint, and reseal with a mould-resistant, neutral-cure wet-area silicone. If the signs point to a failed membrane or a pipe, we’ll tell you straight. That’s a job for a waterproofer or plumber, and resealing over it would only hide the problem.

Most of the leaks we’re called out for are seal failures. That’s why our shower resealing service is often all that’s needed.

Got a shower leaking from the bottom in Melbourne?

Opal Caulking Services fixes shower leaks caused by failed silicone, screen seals and grout across Melbourne. Send us a photo for a free online estimate, or call 0413 377 760. Book a shower leak repair.

Frequently Asked Questions

Can a shower leak from the bottom if the silicone looks fine?

Yes. Silicone can look intact on the surface but have lost its grip on the tile underneath, letting water slip behind it. Queensland’s building regulator lists peeling or discolouring silicone as a warning sign, but adhesion failure isn’t always visible. Pressing gently along the joint or doing a zone-by-zone water test will usually reveal it.

Is a shower leaking from the bottom an emergency?

Usually not an emergency, but don’t leave it. QBCC bathroom warranty claims in 2024–25 averaged almost $25,000, mostly from damage that built up over time. Limit use of the shower, keep the floor dry, and get it checked within a week or two, sooner if water is reaching another room or a ceiling below.

Should I call a plumber or a caulking specialist?

It depends on the source. If your water meter moves with every tap off, call a licensed plumber. If water only appears when the shower runs, it’s usually a failed seal, screen seal or grout, which a caulking specialist fixes. Not sure? Start with the shower leak repair check.

How long does it take to fix a shower leaking at the base?

A standard reseal is usually done in a few hours. The new silicone then needs time to cure before the shower is used; Selleys rates its Wet Area Silicone at about 2 mm of cure per 24 hours. See how often you should reseal a shower for aftercare.

The short version

Not sure if your shower is due? Read how often you should reseal a shower, or see our full range of caulking services in Melbourne.

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