Can I fix black bathroom grout or need professional?« Back to Previous Page

That black grout is almost certainly mold, and its persistence after bleach cleaning is a classic sign of a deeper issue. Bleach only removes surface discoloration on non-porous surfaces; it cannot penetrate porous grout to kill the root structure. In Dubai's high humidity, especially in older Deira buildings with less ventilation, this is a very common problem.

For a small, surface-level area, you can try a dedicated grout cleaner or a paste of baking soda and vinegar, scrubbing with a stiff brush. However, if it has returned darker, the mold has likely penetrated deep into the grout and may be growing behind it. In this case, no cleaning product will provide a permanent fix.

The dampness behind the toilet suggests a potential source of moisture, like a tiny leak from the cistern or condensation from cold-water pipes, that is constantly feeding the mold. A professional can identify if this is the case. For persistent or recurring mold, the only permanent solution is to remove the compromised grout and re-grout the area, after first ensuring the underlying wall is completely dry and treating it with an antimicrobial agent to prevent regrowth. Given the humidity, applying a mold-resistant grout and a quality sealant afterwards is critical.

If the affected area is large or you notice a musty smell spreading to other rooms, a professional inspection is recommended to assess the full extent and rule out hidden moisture problems within the walls.