Fighting Hard Water Stains In Toilet
We have just about the hardest water anywhere, and keeping the waterline stains out of the toilet has been impossible. Well my DH brought home some Scouring Sticks a while back, and I just got around to trying one out. It works great! They are made of pumice, and claim to be safe for ceramic tile and porcelain. You gotta put some elbow grease into it, though. I suggest you go ahead and clean the toilet first, so you can see what's really stuck on.
I dumped about 1 and a half gallons of water down the toilet to make it empty out all the water and not refill, so I had a clear shot at it.
Then pre-wet the pumice stone and start scrubbing on the stains. The stains just rub out with the abrasive stone, and make a fine grey "mud" that can be flushed away.
No smelly chemicals, non-toxic. The brand is "Pumie". You can get them at a hardware store or probably on line.