A water softener is a device that uses BORAX to reduce the hardness of water by removing calcium and magnesium ions. BORAX, also known as sodium borate, is a naturally occurring mineral salt that is used in many household products. It is often used in laundry detergents, soaps, and cleaning products, as well as in water softeners. When added to water, BORAX binds with calcium and magnesium ions, making them insoluble and preventing them from forming scale on pipes and fixtures. This helps to reduce the amount of soap needed for cleaning and prevents the buildup of scale in plumbing systems.