Quick Answer
A leaking shower in Melbourne is usually caused by failed silicone sealant, cracked tile grout, or a compromised waterproofing membrane behind the tiles. DIY fixes for silicone and grout cost $30–$80 in materials and stop minor leaks within a weekend. Full re-waterproofing with re-tiling costs $1,500–$5,000 and legally requires a licensed waterproofer under Australian Standard AS 3740. Act early — once water reaches the subfloor or neighbouring rooms, repair costs rise tenfold.
What You’ll Need
Tools
| Tool | Cost | Where |
|---|---|---|
| Silicone removal tool / sharp Stanley knife | $10–$25 | Bunnings, Mitre 10 |
| Caulking gun (skeleton frame) | $12–$25 | Most hardware |
| Grout saw or rotary tool with grout bit | $15–$80 | Total Tools, Bunnings |
| Plastic putty knife / smoothing tool | $5–$15 | Most hardware |
| Microfibre cloths and methylated spirits | $10–$15 | Supermarket or hardware |
| Painter’s tape (low-tack) | $5–$10 | Most hardware |
| Wet/dry vacuum (for grout removal dust) | $80–$200 or hire | Total Tools, Kennards Hire |
Materials
| Material | Cost | Use |
|---|---|---|
| Selleys Wet Area silicone (300ml) | $15–$25 | Tile-to-hob, tile-to-screen joints |
| Bostik Wet Area silicone (300ml) | $12–$20 | Alternative to Selleys |
| Sanded wall grout (2kg) | $15–$25 | Re-grouting tile joints |
| Liquid waterproofing membrane (1L) | $50–$120 | Behind tiles — licensed work only |
| Methylated spirits (1L) | $8–$12 | Cleaning before silicone |
| Tile sealant (water-based) | $25–$45 | Sealing porous grout |
Why Shower Leaks Happen in Melbourne Homes
Most leaking showers in Melbourne’s SE suburbs (Frankston, Dandenong, Berwick, Pakenham, Cranbourne, Officer) follow predictable patterns. Melbourne bathrooms built between 2005–2015 often used cheaper silicone that fails after 8–10 years. Pre-2005 bathrooms predate the current waterproofing standard (AS 3740-2010) and frequently have no proper membrane behind the tiles at all. Houses built post-2010 should have full compliant waterproofing, but installation defects (failure to flash the floor waste correctly, gaps where the membrane meets the door reveal) are surprisingly common.
The clay soils common across SE Melbourne also cause minor house movement through summer and winter. That movement opens up hairline cracks in grout and stretches old silicone past its elasticity, especially at the inside corners of the shower and the join between tiled walls and the shower base.
The good news: 70% of shower leaks reported on Whirlpool and Reddit r/AusRenovation are surface-level — silicone or grout failures that a confident homeowner can fix in a weekend without trade help. The remaining 30% require licensed waterproofing work and shouldn’t be DIY’d.
How to Find the Source of a Leak
| Visible sign | Likely source | DIY-fixable? |
|---|---|---|
| Mould or dark stain along silicone bead | Failed silicone sealant | Yes — $15–$25, weekend job |
| White efflorescence on grout lines | Cracked grout, water seeping in | Yes — $20–$40, weekend job |
| Damp wall on opposite side of shower | Waterproofing membrane failure | No — licensed waterproofer needed |
| Lifting or hollow-sounding floor tiles | Substrate water damage | No — major repair |
| Smell of mildew, no visible leak | Cavity moisture, possible rot | No — needs inspection |
| Water pooling at door reveal after shower | Hob too low or seal failure | Partial — assess first |
| Slow drip from tap when off | Worn cartridge or O-ring | Yes — $10–$30 part |
Step-by-Step: Fix the Most Common Shower Leaks
Step 1: Diagnose Before You Cut
Run the shower for 5 minutes on cold (no condensation to confuse the result). Stop, towel-dry every surface, and inspect again 30 minutes later. Any new damp patches that appear are your leak entry point. Common spots: the inside corners where two tiled walls meet, the bead along the top of the shower hob, the silicone where the glass screen meets tile, and around the floor waste.
If damp shows up on the opposite side of the wall (e.g., dark mark on the bedroom wall behind the shower) stop the DIY plan — that indicates membrane failure, not surface sealant. Call a licensed waterproofer.
Step 2: Remove the Old Silicone
Tape both edges of the silicone bead with low-tack painter’s tape, leaving a 4mm gap exposed. This stops the knife from scratching the tile. Use a fresh Stanley blade or a silicone removal tool to slice along both edges of the bead, then peel the strip out. Stubborn residue comes off with a silicone-remover gel (Selleys Silicone Remover, $12) or methylated spirits and a microfibre cloth.
Critical: the surface must be 100% dry and free of old silicone residue. New silicone will not bond to old silicone or to wet substrate. If you skip the cleaning step, the new bead will fail within months.
Step 3: Apply Fresh Wet-Area Silicone
Cut the nozzle of a Selleys Wet Area silicone tube at a 45° angle, opening size matched to your gap (3–5mm typical). Load the caulking gun, then run a smooth continuous bead along the joint — don’t stop mid-line, as joins are weak points. Wet your gloved finger or a smoothing tool with soapy water and press the bead to a concave profile within 60 seconds of applying.
Peel both pieces of painter’s tape off before the silicone skins over (within 5 minutes). Leave to cure 24 hours minimum before using the shower — 48 hours is safer in humid weather. Most failures come from showering too soon.
Step 4: Re-Grout Cracked Joints
For minor cracks in grout (less than 2mm wide) — a common problem for tiled bathrooms in older homes — grind out the failed grout with a manual grout saw or a rotary tool fitted with a grout-removal bit (Dremel 568, $40). Take grout down to 3mm depth across the affected joint — less and the new grout won’t bond, more and you risk damaging the membrane below.
Vacuum out all dust. Mix sanded grout to a thick peanut-butter consistency. Press into joints using a rubber float held at 45°, then wipe away excess with a damp sponge in circular motions. Wipe again after 20 minutes to remove the haze. Cure 24 hours before water exposure. (Considering retiling the whole bathroom floor while you’re at it? See our floor tiling cost guide.)
Step 5: Seal the Grout
Once the new grout has cured for 7 days, apply a water-based tile grout sealer with a small brush. This is the step most DIY-ers skip, and it’s the reason re-grouted showers leak again within 18 months. Two coats applied 30 minutes apart, allow to dry 4 hours.
Step 6: Check the Floor Waste
The floor waste (drain) is a common slow-leak source. Lift the chrome grate and inspect the rubber gasket inside — if it’s perished or cracked, a replacement is $8–$15. Clean accumulated hair and soap scum out of the trap. If the floor around the waste is soft or hollow, call a plumber — this indicates substrate damage from a previous leak.
Step 7: Address the Tap or Mixer
A slow drip from the showerhead when the tap is off indicates a worn cartridge or O-ring. For most modern mixer taps (and other common plumbing jobs) (Caroma, Methven, Phoenix), this is a 20-minute DIY fix: isolate water at the main, remove the handle, unscrew the bonnet, lift out the cartridge, replace with an exact-match new one ($25–$60), reassemble.
Step 8: Test and Monitor
After 24–48 hours cure time, run the shower for 10 minutes. Towel-dry every surface and inspect again at 30 minutes, then again the next morning. Any persistent damp means the leak wasn’t in the silicone or grout — it’s deeper, and you need professional help. Mark a calendar reminder to re-inspect at 3 months, 6 months, and 12 months — catching micro-failures early is the difference between $30 and $3,000.
Troubleshooting
| Problem | Likely cause | Fix |
|---|---|---|
| New silicone peels away within weeks | Surface had old silicone residue or moisture | Strip and re-do; clean with metho, dry 24h, use wet-area-rated silicone |
| Grout cracks again within 6 months | House movement or unsealed grout | Apply grout sealer after re-grouting; consider epoxy grout for high-movement joints |
| Damp returns despite sealing surface joints | Membrane behind tile has failed | Call licensed waterproofer — surface fixes alone won’t solve this |
| Black mould keeps coming back on silicone | Wrong silicone grade or poor ventilation | Use Selleys Wet Area Anti-Mould; install exhaust fan if missing |
| Tap still drips after cartridge swap | Wrong cartridge or worn valve seat | Take old part to specialist; if seat is pitted, replace whole tap body |
When to Call a Professional
In Victoria, shower waterproofing behind tiles is regulated under Australian Standard AS 3740-2010 and must be installed by a licensed waterproofer. The Victorian Building Authority issues these licences and lists practitioners on their public register. Surface-level cosmetic work (silicone replacement, grout re-application) does not require a licence — that’s why this guide focuses there.
Call a licensed waterproofer or plumber if:
- The leak appears on the opposite side of the wall, ceiling below, or floor outside the bathroom
- Tiles are loose, hollow-sounding, or visibly bowed
- You’ve done surface repairs but the leak returns within 4 weeks
- The shower base feels spongy or moves underfoot
- There’s any sign of subfloor or stud rot (sagging skirting, soft drywall, damp odour)
- The home is pre-1990 with no record of waterproofing upgrades
A full re-tile and re-waterproof of a standard 1.5m×1.5m shower in SE Melbourne typically costs $1,500–$5,000 depending on tile selection and demolition required. Quotes vary widely — get 3 from VBA-licensed waterproofers, not handymen.
Top 10 Tips and Gotchas
- Always buy “wet area” or “sanitary” silicone. Generic silicone harbours mould within months. Selleys Wet Area or Bostik Sanitary are the standard.
- Mask both edges of the bead with painter’s tape. A 4mm gap between two pieces of tape gives a perfectly straight bead and prevents knife scratches.
- Peel tape off before silicone skins. Within 5 minutes of applying. Tape pulled off cured silicone tears the bead.
- Never use kitchen/window silicone in a bathroom. Most aren’t mildew-rated and lack the fungicide additives wet-area products contain.
- Wait 24 hours before water exposure. 48 hours in humid weather. Premature water flushes uncured silicone out of the joint.
- Don’t overfill grout joints. Press in, wipe excess. Grout sitting proud of the tile surface is weaker and traps soap scum.
- Seal grout after curing. 7-day cure, then 2 coats of water-based sealer. Unsealed grout is porous and re-fails fast.
- Replace the floor waste gasket every 5–7 years. $8 part, 10 minutes, prevents one of the most common slow-leak sources.
- Ventilation is half the battle. An exhaust fan rated for the room volume (check the Quietflo / Mertik labels) cuts mould regrowth by 80%+.
- If unsure — pause and price a pro. A 30-minute leak inspection from a licensed waterproofer is $80–$150 in SE Melbourne and tells you exactly what you’re dealing with before you spend money on the wrong fix.
Local Melbourne Resources
- Reece Plumbing — cartridges, replacement tap seals, professional-grade silicone (Dandenong, Frankston, Berwick branches)
- Bunnings — Selleys and Bostik silicone, grout, sealer, basic tools
- Mitre 10 — alternative grout and silicone brands
- Total Tools — rotary tools, grout saws, professional sealant guns
- Kennards Hire — wet/dry vacuum hire for grout-removal dust
- Victorian Building Authority — licensed waterproofer register, AS 3740 compliance
FAQ
How can I tell if my shower leak is in the silicone or the waterproofing membrane?
Surface silicone failures show damp inside the shower itself — mould along the bead, damp grout, water tracking down the inside corners. Membrane failures show damp outside the shower — on the other side of the wall, ceiling below, or hallway floor adjacent. If you fix the silicone twice and it keeps coming back within weeks, the membrane is the real problem.
How long does Selleys Wet Area silicone last in a Melbourne bathroom?
8–12 years with proper ventilation and regular cleaning. Without an exhaust fan, expect 4–6 years before mildew gets inside the bead. Coastal SE suburbs (Frankston, Mornington) see slightly shorter life due to salt air; inland suburbs (Berwick, Pakenham, Cranbourne) get the full 10+ years.
Can I re-grout over the top of old grout?
No — new grout won’t bond to old. You must grind out the failed joint to at least 3mm depth before applying new grout. Re-grouting over the top might look OK for a few weeks, but it cracks and falls out as a continuous strip within months.
Is it worth using epoxy grout for showers?
For high-movement joints (where wall tile meets floor tile, or at internal corners), epoxy grout is more flexible and waterproof than cement-based grout. Cost is $40–$80 per 1kg vs $15–$25 for sanded grout, but lifespan triples. Worth it for inside corners specifically; cement-based is fine for the main field tiles.
My shower screen is leaking at the bottom — what’s the fix?
Most frameless or semi-frameless screens have a rubber sweep along the bottom of the door and a drip strip beneath the fixed panel. Both wear out in 5–8 years. Replacement strips cost $15–$40 from glass merchants and clip into the existing channel. Take the old strip in for matching — profile sizes vary.
Do I need a permit to do my own shower repairs in Victoria?
No permit needed for cosmetic work — replacing silicone, re-grouting, swapping tap cartridges. Building permits are required when replacing the waterproofing membrane, demolishing tile work, or altering plumbing. The Victorian Building Authority website lists exactly what qualifies as “minor maintenance” (no permit) versus “building work” (permit required).
The grout looks fine but I still smell mildew — what now?
That smell almost always means water has reached the wall cavity or subfloor and mould is growing where you can’t see it. Surface fixes won’t solve this. Get a licensed waterproofer to do an invasive inspection (small access cut through the wall or tile lift) before the rot spreads. Catching it early can keep total cost under $500; ignoring it for a year typically pushes it past $5,000.
Final Thoughts
Most shower leaks in Melbourne are silicone or grout failures — surface jobs any reasonably handy homeowner can fix in a weekend for under $80 in materials. The key is catching them early. By the time damp reaches the opposite side of the wall, you’re facing a $2,000+ licensed-waterproofer job instead.
Here’s the bottom line:
- Check shower silicone and grout every 6 months — takes 5 minutes
- Replace silicone every 8–10 years as preventive maintenance (don’t wait for failure)
- Always use wet-area-rated products (Selleys / Bostik / Sika)
- If a leak shows up outside the shower (other side of wall, ceiling below) — stop DIY, call a licensed waterproofer
- Run the exhaust fan during AND for 20 minutes after every shower — ventilation halves silicone replacement frequency
Pair this work with: bathroom renovation cost guide, bathroom tiling costs, and plumber call-out rates if the fix turns out bigger than expected.
Surface fixes are easy and cheap. Membrane fixes are expensive and licensed. Knowing the difference saves real money.
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