Cracked or missing grout around a shower drain is one of those bathroom maintenance tasks that homeowners often put off — but ignoring it can lead to water seeping under the tiles, causing mould, structural damage, and eventually a much more expensive repair job. If you have noticed loose tiles, dark staining, or a musty smell near the base of your shower, the grout around the drain is likely the culprit. As a trusted plumber in Sydney, Hero Plumbing sees the downstream effects of ignored grout failures regularly, and this guide will help you fix it before it becomes a bigger problem.

Why Does Grout Around the Shower Drain Crack?

Movement and settlement: Sydney homes built on clay-heavy soil experience ground movement across seasons, which causes minor shifting in the floor structure that cracks rigid grout joints.
Drain movement: If the drain body shifts slightly — from foot traffic, a loose drain cover, or ground movement — it puts shear stress on the surrounding grout.
Age and shrinkage: Cement-based grout dries and shrinks over time, eventually pulling away from the tile edges and the drain flange.
Inadequate waterproofing beneath: In older Sydney bathrooms, the original waterproofing membrane may have failed, allowing moisture to get under the screed and cause the tiles to flex.
Chemical cleaning products: Harsh cleaners erode grout over time, making it porous and eventually crumbling.

What You Will Need

Grout rake or oscillating multi-tool with grout blade
Stiff brush and vacuum cleaner
Premixed waterproof grout or unsanded grout powder (match the existing colour as closely as possible)
Grout float or small rubber squeegee
Sponge and bucket of water
Grout sealer (spray-on or brush-on)
Silicone sealant rated for wet areas (for the joint directly against the drain flange)

Step-by-Step: How to Regrout Around a Shower Drain

Step 1: Remove the Old Grout

Use a grout rake or oscillating multi-tool to rake out the old, cracked grout to a depth of at least 3-4mm. Work carefully around the drain flange — you do not want to scratch the drain cover or crack a tile. Remove ALL the old grout from the affected joints, not just the visibly cracked sections. Partial regrout jobs look patchy and the new grout will not bond properly to old grout. Vacuum out all loose debris from the joints and brush clean with a stiff brush.

Step 2: Inspect for Underlying Issues

Before applying new grout, look closely at what is underneath. Are tiles lifting or hollow-sounding when tapped? Is there visible mould or dark staining under the tile edges? Can you see daylight or feel air movement indicating a gap in the substrate? If yes, the problem is deeper than the grout and you should stop here and call a tiler or plumber — regrouting over a failed waterproofing membrane will not fix the underlying issue. If the tiles are solid and the substrate looks sound, proceed.

Step 3: Check the Drain Flange

While the grout is removed, check the drain flange where it meets the tile surface. If there is a gap between the flange and the tile, or the flange is sitting proud of the tile surface, this needs to be addressed before regrouting. A drain sitting even 1-2mm above the tile will allow water to pool around the edge and the new grout will crack again quickly. If the drain is loose, address it first — see our article on leaking shower drains, or if you need help with a blocked drain in Sydney, we cover that separately.

Step 4: Apply New Grout

Mix your grout to a smooth, peanut-butter consistency (or use premixed). Apply it to the joints using a grout float held at a 45-degree angle, pressing firmly to pack the grout fully into each joint. Work in small sections. Scrape excess grout off the tile surfaces with the float edge as you go. Do not worry about getting it perfectly clean at this stage — you will clean up in the next step.

Step 5: Clean Up and Shape

After about 15-20 minutes (when the grout has started to firm but not fully hardened), dampen a sponge and wipe the tile surfaces in a circular motion to remove grout residue. Rinse the sponge frequently and use a light touch — you do not want to pull the fresh grout out of the joints. Shape the joints slightly concave with the edge of the sponge for a neat finish. Let the grout cure for the time specified on the packet — typically 24 hours before any water exposure.

Step 6: Seal the Grout

Once the grout is fully cured (at least 48-72 hours), apply a grout sealer to all the joints around the drain. Sealer penetrates the grout and makes it water and stain resistant. This is especially important in shower floors where the grout is constantly wet. Apply a second coat after the first has dried if using a spray-on sealer.

Step 7: Silicone the Drain Flange Joint

The joint directly between the drain flange and the tile should be sealed with silicone sealant rather than grout. Grout is rigid and will always crack at this joint due to slight movement. Silicone is flexible and maintains a watertight seal. Apply a neat bead of wet-area silicone, smooth it with a wet finger, and allow to cure for 24 hours before using the shower.

When to Call a Professional

Regrouting is a manageable DIY task for most homeowners. However, call a professional if tiles are hollow or lifting, if the waterproofing membrane below the tiles has failed, or if water is actively leaking through to the ceiling or floor below. These situations require a licensed waterproofer and possibly a plumber — and our emergency plumber in Sydney can assess any plumbing-related component of shower leak repairs.

Hero Plumbing: Your Sydney Bathroom Plumbing Experts

From shower drain repairs to full bathroom replumbing, Hero Plumbing services every suburb in Sydney with same-day availability, upfront pricing, and fully licensed plumbers. Call us today to book an inspection or repair.