Remove Hard Water Stains on Sinks and Bathtubs. Hard water stains can be tough remove but we’ve a great tip to remove hard water stains from quick and easy. Hard water stains can be unsightly and difficult to remove, but with the right techniques and cleaning products, you can restore the shine to your sinks and bathtubs. Here are some tips from Haley’s Hints to help you remove hard water stains: 1. Vinegar Solution: Fill a spray bottle with equal…