Its a unit that is used to soften water, by removing the minerals that cause the water to be hard. When water is hard, it can clog pipes, damage boilers, heat exchangers, and many other devices. Water softening can prevent these negative effects. Hard water causes a higher risk of lime scale deposits in industrial, commercial and household water systems. Due to this lime scale build-up, pipes are blocked and the efficiency of hot boilers and tanks is reduced. This increases the cost of domestic water heating by about fifteen to twenty percent.
Its a act of reducing the dissolved calcium, magnesium, and to some degree manganese and ferrous iron ion concentration in hard water. A common water softener is sodium carbonate (Na2CO3).