According to Water & Wastes Digest, magnetic water softeners soften hard water with magnets instead of chemicals. Hard water leaves unsightly residue in appliances and reduces the efficacy of soaps and detergents. As the water flows through a magnetic water softener, the magnets change the shape of the mineral molecules and encourage them to clump together into tiny rounded clusters that do not easily adhere to hard surfaces.
Magnetic water softeners are an alternative to chemical treatment with anti-scale chelation compounds, resins and other additives. Other approaches to water softening involve reverse osmosis and ion-exchange resins. The primary difference between these methods and magnetic water softening is that magnets do not alter the chemical composition of the water. The minerals remain, but are less likely to form deposits on appliances and in water pipes.
Another approach to water softening is lime softening, which works according to principles similar to softening with ion-exchange resins. This technique involves adding a lime solution to the water supply. Lime binds preferentially with calcium and magnesium, bringing them out of solution with the surrounding water. Lime softening is a versatile process that also removes iron, organic waste, many potentially harmful bacterial strains and toxins, such as arsenic.