Why Is My Grout Turning Black?

Black grout is almost always caused by mold and mildew growth, especially in Florida's humid climate. Grout is porous — without a sealant, it absorbs moisture, dirt, and bacteria that feed mold. Other causes include tracked-in dirt compacting into the grout lines over time, hard water mineral deposits, and cleaning products leaving residue that darkens. The fix is professional deep cleaning followed by sealing to prevent it from returning. DIY methods like bleach only treat the surface and can weaken grout over time. Call Treasure Coast Tile & Grout at (772) 879-5722 for permanent results.