The largest application of ion exchange to water treatment is in the area of water softening. This is the process of removing calcium, magnesium and other polyvinyl cations in exchange for sodium ions. Common uses for water softening are in residential and commercial applications for ease of cleaning, improved laundry and dish washing and a reduction in scaling leading to more efficient use of energy in hot water heating. The solution that is used to regenerate the water softeners is concentrated salt water called brine.