3 Stains To Be Wary Of On Basement Walls


Ever wonder why basement waterproofing is so popular? Take a look at your basement or crawl space’s walls. Basement walls are generally in contact with moist soil, so the moisture seeping through your home’s foundation carries all kinds of interesting particles with it. The extra particles hitching a ride with the moisture can leave some strange stains on your basement walls. It’s natural to question whether they’re a threat to your health or home, so let’s go over the common three homeowners see. What does your stain look like?

White, Powdery, and Almost Glittery

This is called efflorescence. Good news, it’s not mold! Efflorescence is a loose mineral salt from the ground that is deposited on concrete basement wall surfaces after water carrying the mineral salts passes through the concrete. It’s a little ugly and alarming to find on your walls, but it is not a hazard to your health and it’s fairly easy to clean up.

Dark Black Or Grey

A grey or black stain is very likely a kind of mold. This is the one type of stain you need to be especially worried about, as the EPA reports that everytype of mold has the potential for mild to severe health effects. Mold is a surefire sign that your basement’s humidity has gone too far.


A rusty stain typically means there is some iron ochre infiltration. This is particularly common in areas like the Pacific Northwest of the U.S., where there are high concentrations of iron in the soil. Don’t worry, it’s not harmful to your health! It can be harmful to your plumbing, though, as the iron can build up and cause clogs. The other bad news is that iron ochre stains spread easily and are near impossible to remove. You’re better off covering them up with something stain resistant if the sight bothers you.

There’s almost no such thing as a dry basement, so consider waterproofing to avoid future issues. Moisture removal is your friend when you want to avoid dangerous mold removal. Crawl spaces have the same issues! Ask a professional how to keep your crawl space moisture free, and you can avoid the weird stain issue before it even happens.