How can I get concrete block back to its original color? Water leaked in on 1 wall in the basement.?

Question

It's darker than the surrounding blocks. This happened a year ago, and 5-6 years ago.

Answer 1

if the bleach doesnt work try something like CLR. it may be hard water stains. or maybe vinegar.

Answer 2

try washing it down with a mixture of bleach and water, the discoloration may be caused by mold or mildew in the pores of the blocks. If that doesn't work to your satisfaction then you may need to paint the blocks.

Answer 3

Try spraying it with a bleach solution