A nitrate removal system will remove nitrate from water. The most common nitrate removal method is by ion exchange resin.
The current regulatory standard of 50 mg/l nitrate is derived from the standard in the European Union's Drinking Water Directive. which is intended to ensure that drinking water will not cause methaemoglobinaemia.
How do I remove Nitrate
The most common method of removing nitrate is with an ion exchange resin. The nitrate rich water passes over a resin where the nitrate is exchanged for chloride ions. When no more nitrate can be exchanged the resin needs to be replaced or regenerated by rinsing with salt. Reverse Osmosis can also remove nitrate from water. The water passes through very small pores at a high pressure. This combination stops most contaminants just allowing water molecules through. However RO systems are relatively expensive, may require the water to be pre-treated, and often remove beneficial minerals. They also give relatively low flow rates (litres/day).