Well, apparently many of us are vying for the 'hard water capital' title, lol! At any rate, we've been using the pumice stones for years in our toilets with no ill effects. I have made the mistake of using CLR straight from the bottle (not diluted) on my bathroom counter and tub drain. Big mistake. No finish left there. We need to replace our kitchen faucet probably every 5 years or so due to the mineral buildup that just can not be cleaned from there.