Does bleach kill mould? The truth (and what to use instead)
Quick answer
Bleach can kill surface mould on hard, non-porous surfaces like tiles and glass, but on porous surfaces like plaster, grout and wood it mostly just bleaches the stain white while the roots survive underneath. For porous surfaces, an anti-microbial mould treatment works better.
The bleach myth
Bleach is the default weapon against mould, and on hard, non-porous surfaces — glass, glazed tiles, metal — it does kill surface growth. The problem is that most mould in homes grows on porous surfaces: plaster, grout, wood, painted walls. There, bleach behaves very differently.
Why it fails on porous surfaces
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Mould roots (hyphae) grow into porous materials. Bleach is mostly water plus a bleaching agent; the water soaks in (feeding the mould), while the active part stays on the surface. The result: the stain turns white so it looks gone, but the roots survive and regrow — a big reason mould comes back after cleaning.
What to use instead
For porous surfaces, a purpose-made anti-microbial mould treatment penetrates and kills more effectively than household bleach. Whatever you use, the golden rule is unchanged: you must also fix the moisture source, or any product is a temporary fix.
When to skip DIY entirely
If the mould is extensive, in the plaster, or keeps returning, no spray will solve it. That's when mould treatment and fixing the moisture source is the real answer, with professional mould removal for contaminated material. An mould inspection tells you which you're dealing with.
Bleaching the same spot over and over? book a €75 inspection and we'll fix the cause, or call +357 96 738151.
Frequently asked questions
Does bleach actually kill mould?
Why does mould come back after I use bleach?
What kills mould better than bleach?
Is it safe to use bleach on mould?
Get a fixed quote
A €75 inspection gives you a fixed quote — no guesswork.