White Powder on Basement Walls? A Practical Guide to Efflorescence and Moisture Control
If a stubborn white, chalky residue keeps appearing on your basement walls, you’re likely seeing efflorescence—a mineral deposit left behind when water moves through masonry and evaporates. As moisture travels through concrete or brick, it dissolves naturally occurring salts. When that moisture reaches the surface and dries, the salts crystallize into a powdery film. While…
If a stubborn white, chalky residue keeps appearing on your basement walls, you’re likely seeing efflorescence—a mineral deposit left behind when water moves through masonry and evaporates. As moisture travels through concrete or brick, it dissolves naturally occurring salts. When that moisture reaches the surface and dries, the salts crystallize into a powdery film. While efflorescence itself is not toxic, it signals ongoing moisture movement, which is the real issue to address. Identifying the source of that moisture is the first step toward a long-term solution.
Efflorescence returns because moisture keeps returning. Common sources include groundwater seepage through foundation walls, poor exterior drainage, high indoor humidity, plumbing leaks, or condensation from temperature differences. To confirm you’re dealing with efflorescence—not mold—look for a white or light-gray powder that dissolves in water and has no musty odor. Mold often appears darker and fuzzy and may have a distinct smell. Peeling paint can also accompany moisture problems, but the powdery residue itself is typically mineral salts. Understanding these distinctions helps you respond appropriately.
