Nitrate/Nitrite Rule
Compliance with the Nitrate/Nitrite Rule is required by the Public Water Supply Rules of the Administrative Rules of Montana (ARM 17.38.216), which adopts the Code of Federal Regulation (CFR 141.23).
Forms and Links
- Consumer Factsheet on: Nitrates/Nitrites by EPA
- Technical Factsheet on: Nitrates/Nitrites by EPA
– Compliance help from EPA for system with Nitrate/Nitrite problems
– Used to update contact information for your system
– Summary of federal Public Notice Rule
– Contains example public notices for various violations
Q: What is Nitrate? A:FAQ
~We understand that sampling requirements can be complicated and we encourage you to call us whenever you have a question.~
Nitrate (NO3-) is an inorganic chemical composed of nitrogen and oxygen. Nitrate contamination of drinking water usually results from microorganisms breaking down fertilizers, decaying plants, manures and other organic residues. Due to its high mobility sometimes rain or irrigation water can leach them into groundwater. Nitrates do occur naturally in some groundwater, in most cases higher levels are thought to result from human activities.
Common sources include, but are not limited to:
- Fertilizers and manure
- Animal feedlots
- Municipal wastewater and sludge
- Septic systems
Q: How often is monitoring required? A:
All public water supplies (PWS) are required to monitor their water for the presence of nitrate/nitrite. Groundwater and Surface Water systems typically monitor once a year at each entry point to the distribution system which is representative of the each well after treatment (e.g. water softener, cartridge filtration, chlorination, etc…).
Q: How Much Nitrate/Nitrite is allowed in drinking water? A:
The maximum contaminant level (MCL) for nitrate in drinking water is 10 mg/L. The MCL for Nitrite is 1 mg/L. These are the maximum allowable level of nitrate/nitrite that may be present in drinking water without a high risk of causing health problems. The action level for nitrate is >50% the MCL or 5mg/L. This requires increased monitoring of a system to determine the potential health risk.
Q: What are the Health Effects of Nitrate/Nitrite? A:
Consumers can suffer acute (immediate) health effects from nitrates. Red blood cells carry oxygen to tissue cells and transport carbon dioxide away from the tissue cells. The red color is from the protein hemoglobin. Nitrate oxidizes iron in hemoglobin to create methemoglobin that lacks hemoglobin’s oxygen carrying capacity. This can cause a condition known as "blue-baby syndrome" which can be fatal.
Q: What happens if the MCL Exceeded? A:
A public water supply exceeds the MCL if a nitrate result is above 10mg/L. A confirmation sample for nitrates must be collected within 24 hours of receiving notification of the results from the lab. When a MCL violation is confirmed, public notice must be provided to consumers within 24 hours of being notified by the Department of Environmental Quality (DEQ). The system then has ten days to provide proof that the public notice was issued back to DEQ.
Systems that are sampling once a year will receive notification of increased monitoring for nitrates from DEQ. The system will monitor quarterly (once every three months) for at least four quarter. This increased monitoring may be required until a system is reliably and consistently below the MCL. Systems must remain on increased monitoring until notified in writing by DEQ that they can resume annual monitoring.
Q: Can Drinking Water be treated to remove nitrates? A:
While it is possible to treat nitrates in contaminated groundwater, it can be difficult, expensive, and not totally effective. For this reason prevention is the best way to ensure clean water. Water treatments include distillation, reverse osmosis, ion exchange, or blending.
- Distillation
- Reverse Osmosis
- Ion-exchange
- Blending
Public Notice
Public Water Supplies must comply with the Public Notice Rule and notify their customers whenever they violate federal or state regulations; this includes contaminant violations and monitoring and reporting violations.
EPA has developed the PNiWriter to help operators generate and distribute a public notice that meets all federal requirements. The PNiWriter is a great tool and we encourage operators to use it whenever public notice is required. (PNiWriter Flyer)
Nitrate/NitriteContacts
(Community, NonTransient NonCommunity & Transient)
LAndersen@mt.gov
406-444-5314
Mail To:
Public Water Supply
Attn: Laura Andersen
P.O. Box 200901
1520 East 6th Avenue
Helena, MT 59620-0901
~Please contact Laura Andersen with feedback for this webpage.~
