Add 1 cup bleach to 1 gallon water.
Dip a scrubbing brush into the bleach solution and then scrub over the brown stains. Bleach solution can lighten or completely remove brown stains. Use as much bleach as needed to remove the stains, but don’t soak the wall.
Soak a sponge in clear water and wring it out so that it is damp but not dripping.
Rub the damp sponge over the wall to rinse it and remove the stain residue.
Repeat the process until the brown stains are gone. Finish by rinsing the wall.
Brush a thin but even coat of shellac sealer over the water stains. Let it dry completely for several hours.
Roll a thin layer of stain-resistant primer over the area. This prevents the brown stains from going through the layer of paint and showing on the wall. Let the primer dry completely.
Roll a thin layer of paint on the wall. Use paint that matches the rest of the surface. Let the layer of paint dry completely. Apply another thin layer of paint over the area to match the rest of the surface.
Let the paint dry completely.