Soften hard water with ion exchange water softeners, reverse osmosis, chemicals and lime. Magnetic water softeners, desalination, distillation and electronic water conditioning are increasingly popular alternative water softening systems.
Ion exchange water softeners and resin devices exchange hardness ions for sodium ions, and they replace calcium and magnesium in hard water with potassium and sodium ions. The resins used are organic polymers which release hydroxide ions after removing sulphate, carbonate and bi-carbonate ions from hard water. Most conventional water softening devices and systems depend on ion exchange.
Lime and chelating agents, such as citric acid, are effective in water softening. Limewater added to hard water removes hardness ions through precipitation. It also effectively purifies water and removes a variety of microorganisms and organic matter. Chelating agents detoxify water by binding metals and hardness ions and flushing them out.
Distillation treats hard water by removing nonvolatile salts as it goes through the natural process of evaporation, condensation and precipitation, similar to rainfall. It is ideal for complete or partial separation of hardness ions from water, and it is not always economical. A popular method of softening hard water is through reverse osmosis, a process that uses hydrostatic pressure gradients with a porous membrane. Water molecules pass through the membrane, while hardness ions are trapped and flushed away, resulting in soft water.