How do I remove hard water spots from a polished granite shower wall?

If the spots are light a #00 steel wool pad may remove them. Use the steel wool dry. If the deposits are heavy use a solution of sulfamic acid and water. Sulfamic acid is sold under the name of sulfamic acid crystals and is used for cleaning grout.

TIP To avoid water spots in the future seal the shower wall with a good silicone based sealer and apply a light coat of a good marble wax. Squeegee the shower wall immediately after a shower with a window squeegee.