
We have very hard water in our apartment building. Heavy dark limescale often builds up on the bottom of the toilet, which also clogs the drain holes under the rim. It gets pretty rusty under the rim too. The washing efficiency is greatly reduced. To conserve water here in drought-prone California, I often don't flush water #1 every time. (I live alone.) Calcium in urine can contribute to buildup in the toilet drain. I also use CLR on showerheads and faucets where limescale can negatively affect water flow. That works great. I have a hard time finding it in local stores at times, but I did find a good two pack deal from a third party here at Revain. The delivery was super fast.

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