It is best to send us an image or request an onsite free estimate. Generally, if the water spot is small, you should be able to repaint the surface with an oil-based primer, let it dry thoroughly, then reapply your original color. The final coat does not need to be oil-based. KILZ® offers a great solution. Larger stains can require removal of the affected area. Text Michael with the image at (239) 564-9533, provide your address, and he will schedule a time with your for that free estimate.