When you see a discoloration, act quickly to determine the origin of the stain. Sometimes, ceiling water damage can be something as simple as your child splashing water out of the bathtub where it proceeds to leak through the old caulk job. When you spot a stain, look at its position in the house, and determine what is above it. If there is a bathroom, then you may have a similar situation with the leaking tub, or you could have some leaking pipes. If the ceiling is only slightly colored, and dry to the touch, and you know that indeed some water has been spilled up there recently, then you might be lucky. Keep an eye on the spot, and if it continues to feel dry, just re-caulk your bathtub, and paint the ceiling, using a stain blocking primer.

If the ceiling is wet, the spot grows, the water begins to drip, or if you cannot think of a reason that water would have leaked there, you may have a serious problem. You will have to determine the extent of your problem and to do that you may either have to get into the ceiling to have a look from above or, in extreme cases, open the ceiling from below. If you learn that pipes run above the spot, you may need to call in a plumber or a water restoration expert. If it is the roof above the spot, then you should call a roof repair company to inspect your roof quickly, before matters become worse. Only after the leak has been detected and repaired should you then repair and repaint the ceiling.