It is possible to correct a high nitrate problem once it exists, but it can be time-consuming and expensive. Cleanup costing several times as much as protection points out the importance of careful management to protect groundwater quality. The best option is to avoid excess nitrate in the soil by profile nitrogen testing and accounting for all nitrogen sources. There are three methods for removing nitrate from drinking water, distillation, reverse osmosis and anion exchange. These processes vary greatly in cost, reliability and operation requirements.
Anion exchange operates similarly to ion exchange water softening.
Negatively charged sulfate and nitrate ions are exchanged for chloride, and the exchange media is recharged by a high concentration of chloride in salt brine. Anion exchange has lower operating cost than other methods and is well suited for large quantities of water with low sulfate. With high sulfate water nitrate selective exchange media is essential. When iron levels are elevated, treatment to reduce iron may be required to prevent fouling of the exchange media. When deciding whether to use anion exchange for nitrate removal, the environmental consequences of the salt must be considered.