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Nitrates (NO3) in drinking water usually originates from fertilizers or from animal or human wastes.  Nitrate concentrations in water tend to be highest in areas of intensive agriculture or where there is a high density of septic systems.

What are the Drinking Water Standards?

The USEPA has set the nitrate MCL (Maximum Contaminant Level) standard for drinking water at 10mg/L or 10 parts per million (ppm). 

The Ohio Department of Health has adopted this standard as a non-enforceable health-based standard for private water systems.  Ohio Administrative Code Rules 3701-28-03(S) and (U) require that nitrate are checked for all private water systems during the permit process.  A pre-test is required to determine the approximate level of nitrates in the drinking water.  Results less than 5 ppm do not require any action by the local health district, whereas results 5 ppm or greater require that a sample be collected and sent to a OEPA certified laboratory to be tested.  If the lab results are less than 10 ppm, no further action is required; but if the results are 10 ppm or greater, the local health district is required to provide the property owner information on the health risks of  nitrates and the treatment options.  Both documents are listed below in the next two sections.

What are the Health Effects?

ODH Bureau of Environmental Health's Health Assessment Section – Nitrate Fact Sheet

What are the Treatment Options?

Ohio Department of Health’s Bureau of Environmental Health – Nitrate Treatment Fact Sheet

Additional Resources

Page reviewed 05/29/2018