Then sponge with water and wash in warm water with detergent. Let stand for 30 minutes, then wash as usual. Then dry in the sun and rinse thoroughly. Put salt on the stain. Slowly pour boiling water over the salt and the stain.
Mom recommends club soda, lemon juice, baking soda and or salt.
Take a little mayonaise on you finger and dab it right on the water stain, let it sit for approximately five to ten minutes, or more, remove with a clean cloth. Water stain should be gone. Another tip that I've heard and have tried only once, is to take the ashes from those ugly cigaretts from the ash tray and apply to the water stain. This works too, but I prefer the mayo. For old, dry stains, wet the area thoroughly first with warm water, then cover with baking soda.