ContaminantIn Water AsMaximum Contaminant Level
NitrateWhen pH = 6-10
As(III), arsenite as H3AsO3 and H2AsO31
As(V), arsenate as H2AsO41- and HAsO42
MCL* = 10.0 mg/L (as N)
MCLG** (goal) = 10.0 mg/L (as N) Health Canada
MAC*** = 10 mg/L (as N)
WHO† Guideline: 11.3 mg/L (as N)
50 mg/L (as NO3-1)
NitriteNO2-1US EPA: MCL* = 1.0 mg/L (as N)
MCLG** (goal) = 1.0 mg/L (as N)
Health Canada MAC*** = 1 mg/L (as N)
WHO† Guideline = 1 mg/L (as N)

*Maximum Contaminant Level (MCL) – The highest level of a contaminant that is allowed in drinking water. MCLs are set as close to MCLGs as feasible using the best available treatment technology and taking cost into consideration. MCLs are enforceable standards.
**Maximum Contaminant Level Goal (MCLG) – The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety and are non-enforceable public health goals.
***MAC – Maximum Acceptable Concentration
+WHO – World Health Organization

Sources of ContaminantHuman sewage and livestock manure
Erosion of natural deposits
Potential Health EffectsMethemoglobinemia (blue baby syndrome)
Most potential health effects are seen in infants under the age of 6 months
Treatment Methods
Reverse Osmosis with thin film composite membrane
Anion Exchange (Type I and II, Cl- form, subject to competing sulfates)
Nitrate “Selective” Anion Exchange resins


In the United States the EPA, under the authority of the Safe Drinking Water Act (SDWA), has set the Maximum Contaminant Level Goal (MCLG) for total nitrate/nitrite at 10.0 mg/L and for nitrite at 1.0 mg/L (measured as nitrogen, N). This is the health-based goal at which no known or anticipated adverse effects on human health occur and for which an adequate margin of safety exists. The US EPA has set these levels of protection based on the best available science to prevent potential health problems. Based on the MCLG, EPA has set an enforceable regulation for total nitrate/nitrite, the Maximum Contaminant Level (MCL), at 10 mg/L (10 ppm)(as N) and for nitrite at 1 mg/L (1 ppm)(as N). MCLs are set as close to the MCLG as possible, considering cost, benefits and the ability of public water systems to detect and remove contaminants using suitable treatment technologies.

This information is sourced from the Water Quality Association (WQA) of which WCC is a proud member. Complete reports are available via the links below. This material is shared with the objective of offering comprehensive, professional insights into relevant water quality standards and guidelines.

Nitrite/Nitrates Fact Sheet – Downloadable PDF