How to Remove Mould from Shower Silicone

You remove mould from shower silicone by applying neat household bleach or a thicker silicone-specific mould-removal gel directly to the black staining, leaving it to work for at least 30 minutes, then rinsing thoroughly. Gel products cling to vertical joints better than liquid bleach, which tends to run off before it's had time to work, so gel is usually the better choice around a shower tray or bath edge.

This works well for mould that's sitting on the surface of an otherwise sound bead. It doesn't work for mould that's grown into the silicone itself — that's the distinction that determines whether you need a bottle of bleach or a full reseal.

Mouldy shower silicone keeps coming back after cleaning because mould spores have established themselves inside the silicone's porous surface, not just on top of it — bleach and gel cleaners only kill what they can physically reach. Once the fungus is growing beneath the surface, every clean just knocks the visible colour back temporarily rather than removing the source.

This is one of the most common bathroom issues we see across East London flats, from older conversions in Hackney and Islington with poor ventilation to newer ensuites in Canary Wharf and Southwark that get heavy daily use — the mechanism is identical regardless of the property.

You need to replace the silicone, not just clean it, if the black mark returns within a few weeks of treatment, if you can see a grey or black shadow under the surface even after bleaching, or if the bead has gone soft, cracked, or is lifting away from the tile. Any of those signs mean mould or moisture has got past the surface, and no amount of repeat cleaning will remove it permanently.

• Staining returns within weeks of a thorough bleach or gel treatment
• A dark shadow is visible under the silicone's surface after cleaning
• The bead has cracked, shrunk, or lifted away from the tile or tray
• The silicone feels soft or sticky rather than firm
• Water is getting past the joint onto the floor or through to a ceiling below

You remove old silicone sealant by cutting along both edges of the bead with a sealant knife or box cutter, peeling it away, then scraping off every remaining trace with a plastic scraper before wiping the joint with white spirit or isopropyl alcohol. Getting every last bit of the old bead off matters — new silicone won't bond to any residue left behind, mouldy or otherwise, and a partial removal is the most common reason a fresh reseal fails within weeks.

Once the joint is stripped back to bare tile, grout or acrylic and fully dry, the process of applying and tooling a new mould-resistant bead is exactly the same whether the old silicone was mouldy or just worn out. Our full guide to resealing a shower covers that application step by step.

Call a plumber if mould keeps returning after two or three DIY cleans and reseals, if you find damp, softness or discolouration on the wall or ceiling behind the joint once the old silicone is off, or if the shower tray itself has moved and is no longer sitting flat. Those signs point to water already getting behind the tiles, which a new bead of silicone on its own won't solve.

RenoPlumb strips and replaces mouldy or failed shower silicone across Tower Hamlets, Hackney, Islington, Newham, Southwark and Canary Wharf from our base on Commercial Road in Whitechapel, E1, and we'll check for hidden leaks or tray movement while we're there rather than just laying a new bead over the same problem. See our shower resealing service for details, or call 07460 824073 for a free quote.

The cost depends on how much old silicone has to come out, how many joints are affected, and whether the tiles or tray behind the mould need any repair once it's exposed, so we never quote a figure without seeing the job first. Every visit comes with a free, no-obligation quote, so it costs nothing to find out where you stand. Full detail on how we price jobs is on our pricing page.

Need this fixed by someone local? See our page for a plumber in Hackney for borough-specific coverage and response times.