Soak a terry cloth in distilled water. Terry cloths have a raised nap that will help work away the hard water stains but will not scratch or damage the natural patina.
Rub the terry cloth over the hard water stains. Rub vigorously until you remove the stains.
Apply a dime-sized amount of mineral oil on a clean terry cloth.
Rub the cloth into the hard water stains if you can still see them. Work until the stains are gone.
Buff the fixture dry with a clean cloth.
Buff beeswax onto the fixtures. Buff excess off with a clean cloth. The beeswax will help prevent hard water from redeveloping.