Removing stains due to borewell water in Kalyan, Thane , Maharashtra : Need easy to implement methods

How do you remove the stains caused by borewell water on tiles, toilet bowls ? The water is supplied by our society in toilets and bathrooms. We will not be able to treat these waters prior to use. Kindly advice on an easy to use method to remove the stains. We live at Kalyan near Mumbai, Maharshtra.

Prasanna K
iyerpk71@gmail.com