A water softener is plumbed into the entry of the house. It removes calcium and magnesium from the water and exchanges it for sodium or potassium, depending upon which type of salt you use. It can also ion exchange iron and heavy metals.
Water softeners are self maintaining.
They measure the amount of water used and regenerate at 2 A.M. by backflushing and running salt through the system to remove the hardness minerals. All you need to do is add salt once a month. A water softener is plumbed into the entry of the house. It removes calcium and magnesium from the water and exchanges it for sodium or potassium, depending upon which type of salt you use. A whole house carbon system has at least a cubic foot of carbon is a tank similar to a softener tank with the same type of control valve.