For a small, surface-level patch, a dedicated EPA-approved fungicidal cleaner (not just bleach) applied according to the label can help reduce it. However, if the discoloration returns quickly or is widespread, the moisture source is likely behind the tiles. In many Marina apartments, leaking shower seals or cold water pipes causing condensation inside the wall are the real culprits. Scrubbing the visible surface won’t stop a hidden problem.

When the growth is persistent or you suspect it’s behind the tiles, a professional assessment is needed. They use moisture meters and borescopes to see inside the wall cavity without demolition. The goal is to find and fix the moisture source first; otherwise, any cleaning is temporary. For severe cases, full remediation may involve removing tiles to address the substrate, which is a job for certified technicians to prevent cross-contamination.

In Dubai, remediation should follow standards like the IICRC S520 for mold, which focuses on containment and proper removal. Always ask a provider for their methodology and if they offer post-remediation verification testing from an independent lab to confirm the space is truly clean.