White Whiskers on My Brick Wall

Q. I have a high brick wall in my backyard that has white crystals, or “whiskers”, forming on it.  This is because of the over watering by my neighbor on the other side of the wall.  I asked my neighbor if they would decrease their watering but that hasn’t happened.  I have used vinegar and brushed it off with a stiff brush. I also tried brushing it with a dry brush.  They are not working.  I bought some muriatic acid, but I am afraid to try it because I have plants and trees right by the wall.  I would appreciate any advice you can give me to solve this problem.

Soft deposits on a porous wall are "fuzzy" or can look like white whiskers.

A.  You are correct.  This white, “powder” or “whiskers” is because of the water coming through the wall from your neighbor.  When the wall dries, white “salts” are left behind on the surface of the wall which were previously dissolved in the irrigation water. 

            The only long-term solution is to reduce the amount of water applied on the other side of your wall.  Eventually irrigation water coming through the wall and containing salts will undermine the strength of the wall.

Phosphoric acid is better for the plants than muriatic acid

            I am afraid this is a common problem with no easy solution if your neighbor is not willing to help.  In the meantime, use phosphoric acid rather than muriatic acid to remove white “whiskers” from the wall.  Phosphoric acid is safer to use and the phosphorus contained in the acid is a plant nutrient. 

            Muriatic acid contains chlorine, also a plant nutrient, but needed in very small quantities by plants compared to phosphorus.  Chlorine can be toxic to plants if too much is available.  

            Ultimately, your neighbor’s landscape should have a “dry zone” at least 3 feet wide next to this wall.  This dry zone does not have to be void of plants.  It can contain water conserving plants irrigated with drip emitters. 

Minioasis landscape design

            An even better solution is to convert this landscape to a “desert landscape” using a minioasis landscape design.  Minioasis landscape designs feature high water use areas of the landscape close to the house, located where people like to congregate.  The other areas are designed and landscaped to use less water by having fewer and smaller desert adapted plants.