How to Fix a Water Stain on a Ceiling. Unsightly water stains on the ceiling don't have to ruin the look and feel of a room. Make your ceiling look new again. You can fix a water stain by just following a few steps, buying some basic equipment and doing some prep work.
Analyze the area. Treating light and small stains is much easier than heavier, darker stained areas.
Pour some straight bleach into a small cup for light stains. Use a sponge or rag and dip into bleach. Lightly dab onto the stain until it disappears. Use white chalk or shoe polish to cover very small stains.
Tape off the work area for larger stains. This step will protect any trim and ceiling area that you do not need to fix. Remove any light fixtures or fans or protect them from the paint with tape and cloth.
Apply a coat of the multipurpose sealer over the area and slightly beyond with a roller or a brush. If the paint color is different, then you may need to paint the entire area. For really dark stains use a second coat. Allow to dry according to manufacturer's directions.
Brush or roll the ceiling paint in even strokes. Remove any tape and put back any lights or fixtures.