Water stains often result from plumbing leaks and can quickly cause unsightly marks. They cannot be completely removed, but they can be concealed. Before attempting this project, you will need to locate the source of the leak, have it fixed, and wait for the ceiling to completely dry. Also make sure that there is no mold or mildew to treat before covering the damaged area.
Step 1 - Prepare the Room
Move any furniture and spread the drop cloth on the floor under the stained ceiling. Wear protective eye goggles and gloves because you will be applying chemicals to the ceiling.
Step 2 - Clean with Bleach Mixture
Mix a solution of half bleach and half water, and then apply this with a sponge over the stains. This will lighten the stain and remove any mildew. Use clean water from your spray bottle to rinse away as much of the bleach mixture as possible.
Step 3 - Paint and Finish
Blot the ceiling as dry as you can with the cleaning rags, and allow it to air dry the rest of the way. Then brush on a coat of stain killing primer or mildew resistant primer and allow this to dry. Paint the ceiling area with one or two coats of matching paint.