Hard water is responsible for leaving lime deposits on bird baths. The mineral-rich water flows into the bath and when it evaporates, the mineral deposits are left on that surface, leaving an unsightly stain. If these lime deposit stains are left for long periods of time, they can permanently damage the surface. Removing the stains is not difficult, as long as you have the right tools and knowledge to complete the task.
Things You'll Need
Empty the water from the bird bath. Scrub the surface of the bird bath with water and a firm brush. You may not see a difference at first, but this will remove the top layer of dirt and limescale that is on the bath.
Add vinegar to baking soda until you get a paste-like consistency. Make enough of the paste to cover the stains on the bird bath.
Apply the paste to the stains and allow it to stand for five to 10 minutes. The acid in the vinegar will counteract the minerals left by the hard water.
Rinse the bird bath with water. Make sure not to use the same hard water that caused the stains in the first place.
Do not use the acidic vinegar on fiberglass bird baths. You must buy a special cleaner for fiberglass.