How to Fix a Leaking Shower Base

A wet patch on the bathroom floor after a shower. Damp skirting boards in the next room. A musty smell that won’t go away. These are the quiet warning signs that your shower base is leaking, and most Melbourne homeowners don’t catch them until real damage has already set in.

The good news is that a leaking shower base is fixable. The bad news is that the right fix depends entirely on what’s actually causing the leak. Get it wrong and you’re back to square one within months.

This guide walks you through the common causes, how to identify them, what your repair options are, and when to call a professional.

Why Is My Shower Base Leaking?

Before any repair can work, you need to know where the water is actually escaping. There are five main culprits behind a leaking shower base:

1. Failed Silicone Seals

Silicone is used where the shower base meets the wall and around the drain. Over time it perishes, cracks, or pulls away from the surface. When it does, water finds its way through the gap and into the substrate below. This is the most common cause of shower base leaks and often the most affordable to fix.

2. Cracked or Missing Grout

Grout between tiles is porous. When it cracks, chips, or wears down entirely, water seeps through and reaches the waterproofing membrane underneath. If the membrane is still intact, it holds the water back. If it’s not, you’ll get a leak.

3. Waterproofing Membrane Failure

This is the silent, expensive one. Most shower bases have a waterproofing membrane underneath the tiles. In older Melbourne homes, particularly those built before 2000, these membranes degrade over time. Once the membrane fails, there’s no barrier between shower water and your subfloor or the ceiling below. Surface repairs won’t fix this. The membrane needs to be accessed and replaced.

4. A Leaking or Improperly Installed Drain

If the shower drain wasn’t correctly fitted during installation, or if the seal around it has deteriorated, water can escape directly through or around the drain connection. This type of leak is often mistaken for a membrane issue because the water appears to come from the centre of the shower floor.

5. Cracks in the Shower Tray or Base

Acrylic and fibreglass trays can crack from impact or general wear. Tiled shower bases can crack when the underlying structure moves or settles. Even a hairline crack allows water to escape every time you shower.

How Do You Know Where the Leak Is Coming From?

The flood test is the most reliable DIY diagnostic for a shower base leak. Here’s how to do it:

1. Block the drain. Use a rubber drain plug or a small inflatable test ball (available from hardware stores). This stops water escaping through the normal drainage path.
2. Fill the base. Fill the shower floor with water until it sits about 50mm deep. Mark the water level on the wall with a pencil.
3. Leave it for 30 minutes. Don’t touch the shower during this time. Check whether water is appearing anywhere below (ceiling, adjacent wall, floor of the next room).
4. Check the water level. If the level has dropped below your mark, water is escaping through the base. If it hasn’t dropped, the leak may be coming from somewhere else, like the shower screen, the head, or the wall plumbing.
5. Unblock the drain and re-run. If the flood test showed no leak, run the shower normally and watch where water appears. This isolates the issue to the drain connection or the screen instead.

What Are Your Repair Options?

Not every leaking shower base requires the same fix. The right repair comes down to what’s failed and how far the damage has spread.

Reseal the Base (Most Affordable)

If the leak is caused by perished silicone or cracked grout at the base junctions, resealing is often all you need. Strip the old silicone, clean the area thoroughly, dry completely, and apply fresh neutral-cure silicone. Allow 24 hours to cure before using the shower again. DIY-suitable if the damage is surface-level only.

Repair or Replace the Drain (Mid-Range)

If the flood test points to the drain as the source, a licensed plumber needs to reseal or replace the drain assembly. This is not a DIY job under Australian plumbing regulations. The repair can often be done without removing tiles, depending on access.

Waterproofing Membrane Replacement (Full Rebuild)

When the membrane has failed, there’s no shortcut. The tiles need to come up, the membrane is stripped and replaced to current Australian Standards, and the shower is retiled and regrouted. This is a full rebuild and requires licensed waterproofing and tiling work. Typically takes 5 to 7 working days.

Can You Fix a Leaking Shower Base Without Removing Tiles?

Sometimes, yes. If the leak is coming from the silicone joints at the base or around the drain, and the waterproofing membrane underneath is still intact, a reseal without tile removal is absolutely possible. It’s the most cost-effective outcome and the most common.

However, if the membrane has failed or the substrate beneath the tiles is already saturated and damaged, tiles will need to come up. There’s no way to access and repair a failed membrane through the tile surface. Anyone telling you otherwise is offering a surface-level fix that won’t last.

The only way to know for certain is a proper inspection, not a guess.

Warning Signs the Damage Has Already Spread

A shower base leak that goes undetected doesn’t stay contained. Watch for these signs that water has moved beyond the shower:

• Soft, spongy, or hollow-sounding tiles on the shower floor
• Swollen or discoloured skirting boards on adjacent walls
• Paint bubbling or staining on the ceiling of the room below
• A persistent musty smell in or near the bathroom
• Mould on grout or wall surfaces despite regular cleaning
• Your water meter running even when no taps are on

Any of these signs means the leak has been running long enough to reach surrounding structures. The longer it continues, the more expensive the fix becomes, because structural damage to the subfloor, framing, or ceiling will need to be addressed alongside the shower repair itself.

Does Home Insurance Cover a Leaking Shower Base?

It depends on your policy and the circumstances. Most Australian home and contents policies cover sudden water damage, like a burst pipe or an immediate failure. Gradual damage from a slowly failing waterproofing membrane, particularly where visible signs existed over an extended period, is commonly excluded.

If your shower base has been leaking for months and you’ve been ignoring the signs, an insurer is unlikely to cover the claim. If the damage appears suddenly or is linked to a specific event, you have a stronger case. Check your specific policy wording before assuming you’re covered.

When to Call a Professional

DIY is reasonable if:

• The silicone at the base junction is visibly cracked or pulling away
• The flood test confirms no water loss through the base itself
• The surface grout is the only issue and there are no hollow tiles

Call a professional if:

• The flood test shows water escaping through the base
• Water is appearing in the room below or in adjacent walls
• Tiles sound hollow or feel soft underfoot
• You’ve resealed the shower and it’s still leaking
• The shower is more than 15 years old and hasn’t been inspected
• There’s any visible mould under tiles or on the subfloor
• The drain connection is involved (plumbing work is licensed work in Victoria)

Frequently Asked Questions

How do I know if my shower base is leaking or if it’s the screen?

Run a flood test by blocking the drain and filling the shower base with water. If the water level drops with the drain blocked, the leak is in the base itself. If it holds, run the shower normally and watch where water appears. Leaks that only show during active water flow often point to the screen, head, or wall plumbing rather than the base.

Can I fix a leaking shower base myself?

Resealing the silicone joint at the base and walls is within DIY scope if the membrane underneath is still intact. Strip the old silicone, clean and dry the surface thoroughly, apply fresh neutral-cure silicone, and allow 24 hours to cure before using. If the leak continues after a fresh reseal, the problem is deeper and needs a licensed plumber.

How much does it cost to fix a leaking shower base in Melbourne?

Cost varies depending on the cause and extent of damage. A basic silicone reseal is the most affordable repair. A drain repair or replacement sits in the middle of the range. A full waterproofing membrane replacement with retiling is the most significant investment. Get a proper inspection before committing to any repair approach.

How long does a shower base repair take?

A silicone reseal can be done in a few hours and the shower is usable again the following day. A drain repair typically takes a day. A full membrane replacement with retiling generally takes 5 to 7 working days.

Will the leak get worse if I ignore it?

Yes. Water continuously reaching the substrate causes it to degrade, which allows more water through, which damages surrounding framing, subfloor, and eventually ceilings below. The sooner the leak is caught and diagnosed, the more affordable the fix.

Does VIC Leak Detection repair shower bases, or just detect the leak?

Both. VIC Leak Detection uses advanced acoustic, thermal, and pressure testing to pinpoint the exact source of a shower base leak without unnecessary damage to your property. Where possible, leaks are repaired on the spot.

Is a leaking shower base covered by home insurance?

It depends on your specific policy and the nature of the leak. Sudden damage is more likely to be covered than gradual deterioration. If you’ve had visible signs of leaking over a period of time without acting, many insurers will exclude the claim. Check your policy and contact your insurer promptly with documentation of the damage.