Nitrate is a very soluble substance, easily dissolved in water and extremely hard to remove. Treatment for nitrate is, therefore, very complicated and expensive. Demeralization removes nitrate and all other minerals from the water.
Distillation is one of the oldest, most effective types of demineralization.
The nitrate and other minerals remaim concentrated in the boiling tank. Reverse osmosis is another way to demineralize water. In a reverse osmosis system, the water is put under pressure and forced through a membrane that filters out minerals and nitrate. Higher-yield systems use water pressures in excess of 150 psi. Household units are usually small enough to fit under the sink or on a kitchen counter.