How to permanently remove black, slimy shower grout?« Back to Previous Page

That black, slimy grout is almost certainly a biofilm of mould and mildew, a very common issue in Dubai due to our high humidity and constant AC use creating temperature differentials that cause condensation. Regular bathroom cleaners often can't penetrate the grout to kill the roots.

Start by applying a dedicated grout cleaner or a paste of baking soda and hydrogen peroxide directly onto the affected areas. Let it sit for at least 15-20 minutes to penetrate, then scrub vigorously with a stiff-bristled brush. For persistent growth, a diluted chlorine bleach solution (1 part bleach to 4 parts water) can be effective, but ensure the room is extremely well-ventilated.

The key to a permanent solution is addressing the moisture. Run your bathroom exhaust fan for at least 30 minutes after every shower and ensure it is actually venting properly. Wipe down the shower walls and squeegee excess water after use to minimize standing moisture. If the problem returns quickly after a thorough cleaning, the mould may have penetrated deep into the grout or even behind the tiles.

In many older Dubai villas and apartments, the original grout may have degraded, losing its seal and allowing moisture to seep in. If cleaning provides only a temporary fix, a professional assessment is warranted. They can determine if the grout needs to be professionally removed and re-applied with a high-quality, mould-resistant sealant, which is the only way to create a lasting barrier in our climate.