What If the Black Stains Are Caused by Mold?
Dark grout is not always caused by dirt. In persistently damp environments, particularly bathrooms and poorly ventilated rooms, black or dark stains can sometimes be associated with mold or mildew.
Removing visible discoloration is helpful, but preventing excess moisture is equally important. Improve ventilation, repair leaks, dry wet surfaces, and address persistent dampness whenever possible.
If the discoloration repeatedly returns despite cleaning, or if the grout is cracked, deteriorating, or permanently stained, cleaning alone may not solve the problem. Damaged grout may need to be repaired or replaced.
