The white, powdery bloom on brick and block is efflorescence — mineral salts carried to the surface by water moving through the masonry. It is a stain removal job with a twist: the deposit is the symptom, and the water that delivered it is the actual story.
What it is and where it comes from
Masonry and mortar contain soluble salts. When water enters the wall — rain, ground moisture, a leak — it dissolves them, migrates to the surface, evaporates, and leaves the salts behind as the white crust. The bloom literally maps where water travels through your wall.
New construction often blooms harmlessly in its first year or two as construction moisture leaves. Recurring bloom on established masonry is different: water is getting in from somewhere, repeatedly.
Removing it properly
Dry brushing takes off loose deposit. Bonded efflorescence needs a mild acidic wash — appropriately diluted and thoroughly rinsed, because acid on masonry is a controlled tool, not a splash-on product. Pressure alone tends to drive dissolved salts back into the face to reappear as it dries.
Timing note: cleaning during a wet season often looks defeated within weeks, because the source is still delivering. Remove after addressing water, or accept a repeat.
Reading the warning
Persistent efflorescence in one zone points at its cause: failed guttering above, ground contact and rising damp below, a cracked cap or sill letting water in behind. Fixing that is plumbing-and-flashing territory, not cleaning — but the bloom told you where to look.
Treat recurring bloom as free diagnostics. Clean the wall, then follow the map it drew.
Send photos of where the bloom appears — we will clean it and tell you what the pattern suggests about the water. Read more about stain removal →