Black grout returning after cleaning, need professional?« Back to Previous Page

Black grout in a Marina bathroom is almost certainly mould feeding on the trapped moisture and organic residue. The high humidity, especially during summer, combined with condensation from showers and year-round AC use creates a perfect breeding ground. Bleach only bleaches the surface colour and does not kill the root structure penetrating the porous grout, which is why it returns stronger.

For a lasting solution, start by addressing the moisture. Run the bathroom exhaust fan for at least 30 minutes after every shower and ensure it is actually venting outside, not just into the ceiling void. Wipe down wet tiles and shower walls with a squeegee after use. These habits are critical in Dubai's climate.

If the mould covers less than a square meter and the grout is intact, you can try a targeted approach with a hydrogen peroxide-based cleaner or a dedicated grout mould remover, applied according to the instructions and left to dwell. Scrubbing can release spores, so wear a mask.

However, if the growth is extensive, has returned multiple times, or if the grout is cracked or soft to the touch, the issue is likely deeper. The mould may have penetrated behind the tiles. In such cases, a professional inspection is needed to assess the extent and identify the moisture source. Remediation often involves removing and replacing the compromised grout to fully remove the mould colony, followed by applying a high-quality sealant. A company with a microbiology lab can also identify the mould type to confirm it is a common allergen and not a more problematic species.