Hard water can leave unsightly spots on a stainless steel kitchen sink, and these spots can prove difficult to remove due to the mineral composition of the water. To complicate matters even further, stainless steel is highly sensitive to acid cleaners, which limits your options for cleaning products. Despite these complications, you can remove hard water stains from your sink using products commonly found in the home, using a gentle approach.
Make a paste by mixing three parts baking soda with one part white vinegar. Pour the ingredients into a small bowl and mix thoroughly. Although stainless steel is sensitive to acidic products, white vinegar contains only 5 percent acid and can effectively remove hard water stains without damaging the stainless steel.
Apply your paste to a soft cloth and firmly scrub the hard water stain until the stain disappears. Do not use a scouring pad or other abrasive cloth, as they can scratch the finish on your stainless steel.
Rinse out your sink to remove any loose hard water residue.
Pour lemon juice over the hard water stain, if vinegar and baking soda fail to do the trick. Allow the lemon juice to soak into the stain for about 10 minutes and then scrub it with a soft, non-abrasive cloth. Like vinegar, lemon juice contains enough acid to dissolve hard water, but not enough to corrode stainless steel.