A nitrate removal system will remove nitrate from water. The most common nitrate removal method is by ion exchange resin. Point of use filters can give enough water for one tap or point of entry systems can treat the water for the whole house or factory. Why remove nitrate
Nitrate levels in many waters are often high. Over 60% of nitrate enters water from agricultural land. High concentrations of nitrate in water can cause methaemoglobinaemia in very young children (blue baby syndrome). In extreme cases this can be fatal. The nitrate is converted to nitrite in the body which in turn interferes with oxygen up take in the blood. 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).
Point of Use or Point of Entry
Point of use means removing the nitrate at the point of wanting it, say at the drinking water tap. This has the advantage of only treating the water that you are going to drink without the expense of treating all the other water. Under sink filters can be fitted so water is bled of the incoming cold supply through the nitrate ion exchange filter or RO system and then up to a dedicated tap. The filters however can only treat a small amount of water and need their own tap. They can not be regenerated and need to be replaced every few months. Point of Entry ion exchange systems consist of a valve through which the water flows, down through the ion exchange media and then out of the valve. These systems are big enough to treat the water for the whole house (giving the added protection of treating bathroom water, dishwater water etc). The systems have automatic regeneration with salt so are always ready for use. These Point of Entry systems fit under the sink or in a utility rooms. Point of Entry RO systems exist but are expensive and post treatment to stop the water attacking the plumbing will probably be needed.