Quick Answer

A leaking shower in Melbourne most commonly fails at the grout joints, silicone corners, or waterproof membrane. Minor surface leaks can be fixed DIY with re-grouting and silicone for under $100. If water has penetrated the substrate, expect a full strip-out and re-waterproof job costing $1,500–$4,000. The longer a shower leak goes unfixed, the more expensive the damage becomes — mould, substrate rot, and structural damage multiply the repair bill quickly.

Shower leaks are one of the most common and most ignored problems in Australian homes. In south-east Melbourne, where many homes were built in the 1970s–90s, original waterproofing membranes were either thin bituminous coatings or non-existent. Even newer homes can develop leaks within 10–15 years as silicone ages, grout cracks, and movement joints fail.

Tiler inspecting cracked grout lines in a shower recess corner showing water damage and dark staining around the joint
Cracked grout at the floor-to-wall junction in a shower recess — this corner joint should always be filled with flexible silicone, not grout, because movement in the substrate will crack grout here within 1–3 years.

Diagnosing Where Your Shower Is Leaking

Symptom Likely Cause DIY Fix?
Wet patch on wall or ceiling below shower Failed waterproof membrane or grout No — full investigation required
Mould at grout joints in corners Failed silicone movement joint Yes — remove and replace silicone
Loose or hollow tiles Water behind tiles, adhesive failed No — tile replacement + waterproofing
Efflorescence (white powder) on tiles Water moving through substrate No — professional assessment needed
Damp smell but no visible water Slow leak through hairline grout crack Maybe — regrout and monitor
Dripping from shower waste or base Failed waste seal or base membrane Partial DIY possible (waste seal only)

DIY Fixes: What You Can Do Yourself

Fix 1: Replace Failed Silicone at Movement Joints

Movement joints (internal corners, floor-to-wall junctions) should always use flexible silicone, not grout. Cracked or mouldy silicone is a very common cause of shower leaks and is a genuine DIY job.

  1. Score and remove old silicone using a silicone removal tool or Stanley knife. Remove all traces — new silicone won’t bond over old residue.
  2. Clean thoroughly with methylated spirits on a clean cloth. Let dry completely.
  3. Mask the joint with painter’s tape on both sides to get a clean bead.
  4. Apply sanitary-grade silicone (Selleys Wet Area or equivalent) in a continuous bead without stopping.
  5. Smooth the joint with a wet finger or silicone tool in one pass. Remove tape immediately.
  6. Cure for 24–48 hours before using the shower. Fully cure takes 7 days.
Pro tip: Use white or grey sanitary-grade silicone that contains mould inhibitor — standard clear silicone goes black in shower environments within 12 months.
Plumber applying white silicone sealant bead to floor-to-wall corner junction in a shower recess using a caulking gun
Applying sanitary silicone to the floor-to-wall junction in a shower — this corner joint carries all the movement between the floor slab and the wall and must be flexible sealant, never grout.

Fix 2: Regrout a Leaking Shower

If grout is cracked, porous, or crumbling, regrouting can stop minor seepage. It won’t fix membrane failures, but it’s a worthwhile first step for surface leaks.

  1. Remove old grout using an oscillating multi-tool with a grout removal blade or a manual grout rake. Cut at least 3mm deep.
  2. Vacuum debris and clean joints with a damp cloth.
  3. Mix unsanded grout (for joints under 3mm) or sanded grout (3mm+) to a smooth paste.
  4. Apply grout diagonally with a float, pressing firmly into joints.
  5. Clean excess grout with a damp sponge in circular motions before it sets.
  6. Allow to cure 24–72 hours, then apply grout sealer.

When You Need a Professional

Safety warning: Never retile or waterproof over a substrate that has water damage without first drying it out completely — typically 2–6 weeks with dehumidification. Trapping moisture causes mould growth that can compromise structural timber and create serious health risks.

Call a licensed waterproofer and tiler when you see: damp patches appearing on walls or ceilings outside the shower; tiles that sound hollow when tapped; tiles that have come loose; or any sign of timber rot (soft spots, discolouration) in nearby wall or floor framing.

Repair Type Approx Cost Who Does It
Silicone replacement (DIY) $20–$50 materials DIY
Regrout only $80–$200 materials DIY or tiler $400–$800
Shower waste seal replacement $150–$350 Plumber
Partial retile + waterproof (shower recess) $1,500–$3,000 Licensed tiler/waterproofer
Full strip, substrate repair, waterproof + retile $3,000–$6,000 Licensed tiler/waterproofer
Tiler removing damaged shower tiles to expose the substrate showing water damage and failed waterproofing membrane underneath
Removing shower tiles to assess substrate damage — when waterproofing has failed, the timber framing or compressed fibre cement sheet behind the tiles absorbs water, and the damage is only visible after strip-out.

Top 10 Tips and Gotchas for Shower Leak Repairs

  1. The water entry point and the visible damage are rarely in the same location. A leak at the base waste can appear as a damp ceiling three metres away.
  2. Silicone over grout doesn’t work. The silicone won’t bond to a porous surface and will peel within months. Always remove all old grout from the joint before applying silicone.
  3. Waterproofing is licensed work in Victoria. A tiler who is not also licensed as a waterproofer must engage a separate contractor. Ask to see both licences.
  4. Grout alone is not waterproof. It’s porous — always apply a penetrating grout sealer after grouting shower surfaces.
  5. Re-grouting over old grout doesn’t work. You must remove the old grout to a minimum 3mm depth before applying new grout.
  6. The shower waste is a common failure point. Check the rubber seal and chrome surround are tight and intact. A loose waste fitting allows water under the substrate.
  7. Check for membrane type before DIY sealing. Painting a waterproofing sealer over tiles can trap moisture if the membrane beneath has already failed.
  8. Allow full drying time before retiling. Wet substrates need 2–6 weeks to dry. Retiling over damp substrate guarantees another leak.
  9. Epoxy grout is more water-resistant than cement grout. Consider it for the shower recess floor where water pooling is constant.
  10. Test the repair before grouting. After waterproofing, flood-test the shower base for 24 hours to confirm no seepage before tiling.
Safety expert with orange hi-vis vest checking the shower waste drain fitting with a torch looking for signs of failed rubber seal
Inspecting the shower waste fitting for a failed rubber seal — this is one of the most common causes of shower base leaks and is often overlooked in favour of more expensive retiling work.

Local Melbourne Resources

Frequently Asked Questions

How do I know if my shower is leaking through the tiles or just splashing?

Turn off the shower and seal the waste with a rubber stopper. Fill the base to just below the kerb height and leave for 24 hours. If the water level drops, you have a membrane or substrate leak. If it stays level but you get damp elsewhere when showering, the issue is splash or inadequate sealing around the door or screen.

Can I waterproof over existing tiles to fix a leaking shower?

No. Applying waterproofing sealer over existing tiles is not an approved repair method under the Australian Building Code and is only effective if the tiles themselves are intact and the substrate is dry. Any membrane failure beneath the tiles will cause the overlay to fail within 1–2 years. The correct fix for a membrane failure is strip-out and proper re-waterproofing.

How long does a shower repair take?

A silicone replacement takes 1–2 hours, plus 24–48 hours curing time. A full strip-out and retile takes 7–14 days including drying time, waterproofing cure (minimum 48 hours), and tile adhesive cure. Budget for the shower being out of use for at least two weeks for a major repair.

Is a leaking shower covered by home insurance?

Most standard home insurance policies in Australia exclude gradual water leaks — leaks that develop slowly over time are considered maintenance issues. Sudden damage from a burst pipe may be covered. Always check your specific policy wording, and act quickly if you discover a leak to prevent it becoming a larger and uninsurable problem.

Freshly regrouted and resealed shower recess showing clean white grout lines and new silicone at all corner joints
A regrouted and resealed shower recess — new silicone at all movement joints and fresh grout properly sealed with a penetrating sealer should give another 5–10 years of watertight service.