Nitrates are a chemical used mainly as nutrients for plants and in chemical fertilizers. Animal and human waste also contain nitrogen in the form of ammonia. Nitrate leaching tends to be greater in areas where there are large numbers of livestock.

Nitrate in borehole water is a common problem and can mean that the water supply is not potable.

It is more common when your well is near farm land and is mostly as a result of agricultural operations, farm runoff and fertiliser use. Incidents such as heavy rains, flooding and chemical spills can cause nitrates to enter the soil and therefore contaminate the groundwater. Once in the water they remain there until they are used by plants or organisms.

Nitrates are harmful to the humans, in particular babies but have been linked to a potential cause for Gastrointestinal Cancer in Adults. Nitrates are converted by bacteria in the stomach of infants to toxic nitrites. At levels that would not cause harm to adults, nitrates can cause methemoglobinemia in infants, a condition also known as “blue baby” syndrome.

Nitrates have no colour, taste or smell in water so special tests are needed to determine the levels in a borehole supply. Borehole Engineering Services can carry out this test.

The current legal amount of nitrate allowed in water is 50mg/l with an advised maximum of 25mg/l.

It cannot be removed by boiling the water, in fact this actually increases the concentration.

Water can be treated in a number of ways to remove the nitrate content, reverse osmosis and ion exchange are two such techniques.

Reverse Osmosis

Is efficient, but will only work if the water is free of solid contaminants which can clog up the reverse osmosis membranes. Therefore before reverse osmosis can be used, the water must be cleared of all solids and particles.

More information on reverse osmosis can be found on our website.

Ion Exchange

Requires that chloride, i.e. brine solution be available to provide the chloride ions to be exchanged for the nitrate ions. In practical terms this means that the system must be regenerated by flushing with a brine solution at timed intervals and therefore, must be kept topped up with salt at regular intervals.




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