How do I fix black grout in my Dubai bathroom and can I re-grout myself?

Black grout is almost always mould — specifically Cladosporium or similar bathroom mould species that thrive in warm, damp grout. Standard cleaning products fail because they clean the surface without penetrating the porous grout to kill the mould beneath. What actually works: a thick bleach gel (not liquid bleach — it runs off before penetrating) applied directly to the grout, covered with cling film, and left for several hours. This penetrates and kills the mould rather than just bleaching the surface colour. On re-grouting: for severely stained or deteriorating grout, re-grouting is the proper solution. A handyman can rake out and replace grout in a standard bathroom — it doesn't require a specialist tiler unless tiles need to be removed. For a standard Dubai bathroom, re-grouting costs AED 300–AED 800 depending on the size of the area. For the future, switching to epoxy grout (which is non-porous and mould-resistant) is worth the slightly higher cost — it's the standard recommendation for Dubai bathrooms given the hard water and humidity.