The frustrating thing about water damage is that it happens where you cannot see it. By the time a leaking shower announces itself, moisture has often been travelling behind the tiles for months. Knowing the early signs lets you act while the fix is still a repair rather than a rebuild.
Drummy or hollow-sounding tiles
Tap the tiles in and around your shower with a knuckle. A sound tile gives a solid, dull note; a tile that has lost adhesion sounds hollow or "drummy". Moisture behind tiles breaks down adhesives over time, and drummy tiles — especially low on shower walls or on the shower floor — are a classic sign water is getting behind the surface.
Discoloured or dark grout lines
Grout that stays dark long after the shower has dried is holding water. Watch for grout lines that dry unevenly — patches that remain damp-looking for hours indicate moisture sitting within or behind the joint rather than evaporating off the surface.
Movement in the silicone joints
Silicone that has pulled away from the wall, gone spongey, or shows mould growing underneath the bead (not just on top) means the joint has failed. These junction joints are the highest-stress points in the shower, and once they let go, water tracks straight into the wall junction behind them.
Signs on the other side of the wall
Some of the clearest evidence appears outside the bathroom entirely. Bubbling or flaking paint on the adjoining wall, skirting boards that swell or lift, musty carpet in the neighbouring room, or water stains on a ceiling below the bathroom all point to moisture escaping the wet area. Water travels along framing and floor structures, so damage can surface a surprising distance from the shower itself.
Persistent musty smell
Trapped moisture feeds mould inside wall cavities, and the first sign is often your nose. A damp, musty smell that survives cleaning and airing means moisture is being replenished from somewhere — and the shower is the usual suspect.
What to do if you spot these signs
First, do not panic — and do not reach for the silicone gun. Masking the entry point traps moisture that needs to dry out. Have the shower professionally inspected to confirm where water is escaping. In most cases the entry point is failed grout or perished seals, both of which are repaired without removing tiles, usually in a single day. Caught early, water damage under shower tiles is one of the most fixable problems in your home; left alone, it quietly becomes one of the most expensive.
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