[header] How to get water stains off a ceiling [title] Find the source of the moisture. [step] You may find an obvious leak in a pipe or fixture on the floor above the damaged ceiling, but it may also be more difficult to pinpoint. [substeps] If you don't locate the source of the moisture prior to doing the repair, the problem will just keep coming back. 
Wear gloves, safety glasses and a dust mask while looking for and repairing the leak. Depending on how long the leak has gone unrepaired, there could be mold present.