Nitrates and Nitrites

Maximum Contaminant Level

US EPA:

MCL – 10.0 mg/L or ppm

MCLG – 10.0 mg/L

WHO Guideline – 11.3 mg/L

Nitrates and nitrites are naturally occurring substances that are created by the decomposition of organic matter. The nitrate concentration in surface water is normally pretty low, but can be elevated due to agricultural runoff, refuse dump runoff, or contamination with human or animal wastes.

According to the World Health Organization,

"The increasing use of artificial fertilizers, the disposal of wastes (particularly from animal farming) and changes in land use are the main factors responsible for the progressive increase in nitrate levels in groundwater supplies over the last 20 years." 1

High levels of nitrates can be dangerous for babies or pregnant women because nitrates interfere with the oxygen carrying capacity of the blood. Nitrate in water is undetectable without testing, as it is odorless, tasteless, and colorless. It is highly recommended that any household with pregnant women, infants, nursing women, or elderly people have their water tested for nitrates, as these groups are at higher risk of being affected by high nitrate levels. Nitrates and nitrites are rarely a problem in drinking water for humans older than six months of age.

Nitrates and nitrites can be removed from drinking water via the following methods:

  • Reverse Osmosis with thin film composite membrane
  • Anion Exchange
  • Nitrate “selective” Anion Exchange resins
  • Distillation
1. World Health Organization. Nitrate and Nitrite in Drinking-Water. who.int. [Online] 2011. http://www.who.int/water_sanitation_health/dwq/chemicals/nitratenitrite2ndadd.pdf.