Nitrate-Nitrite in Connecticut Drinking Water
By Alexander Snyder, Founder & Water Quality Data Lead
The U.S. EPA sets the legal limit (MCL) for Nitrate-Nitrite at 10 mg/L, and the health-based safe level set by the U.S. EPA is 10 mg/L. A level that is legal is not always the level science considers fully protective.
Nitrate-Nitrite has been detected in 85 Connecticut ZIP codes, above a limit or health guideline in 24. Here is what you need to know about nitrate-nitrite in your drinking water and how it may affect your household.
What Is Nitrate-Nitrite?
Nitrate-nitrite is a combined measurement of two inorganic nitrogen compounds commonly found together in drinking water. They originate from fertilizer runoff, septic system leachate, sewage discharge, and natural erosion. The EPA maximum contaminant level for the combined total is 10 mg/L. Elevated levels pose the greatest risk to infants under six months by causing methemoglobinemia, a condition that impairs oxygen transport in the blood.
Is Nitrate-Nitrite in Your Water?
Enter your Connecticut ZIP code to find out if nitrate-nitrite is in your local water — and see personalized health risks for your household.
Check Your ZIP CodeHealth Effects of Nitrate-Nitrite
Combined nitrogen compounds that cause methemoglobinemia (blue baby syndrome) in infants. The combined measurement reflects total inorganic nitrogen in water.
Safety Guidelines
Health Guideline
10 mg/L
Source: U.S. EPA
Legal Limit (MCL)
10 mg/L
EPA Maximum Contaminant Level
Nitrate-Nitrite's health-based safe level is set below the federal legal limit.
| Standard | Level | Source |
|---|---|---|
| EPA Legal Limit (MCL) | 10 mg/L | EPA |
| Health Guideline | 10 mg/L | U.S. EPA |
Where Does Nitrate-Nitrite Come From?
Fertilizer runoff; septic system leaching; sewage discharge; erosion of natural deposits; agricultural operations.
How to Reduce Nitrate-Nitrite in Your Water
- 1Install a point-of-use reverse osmosis system certified to NSF/ANSI Standard 58, which typically removes 85 to 92% of combined nitrate and nitrite from drinking water.
- 2Use an ion exchange system with a nitrate-selective resin for whole-house treatment; standard water softener resins are less effective than nitrate-specific resins.
- 3Do not rely on activated carbon filters or boiling, as neither method reduces nitrate or nitrite concentrations; boiling actually increases concentration by evaporating water.
- 4Test well water quarterly if located near agricultural operations, as nitrate-nitrite levels fluctuate seasonally with fertilizer application and rainfall patterns.
Who Is Most Vulnerable to Nitrate-Nitrite?
The safe level of nitrate-nitrite varies significantly depending on who is drinking the water. CheckYourTap calculates adjusted safe levels for each member of your household:
A contaminant level that is safe for an adult may exceed guidelines for an infant by 4-8x or more. Check your ZIP code to see personalized results.
Reading this inside ChatGPT or Claude?
This page can tell you the general science, but not what is actually in your water’s nitrate-nitrite level — that depends on your exact address. You can get your specific answer two ways:
- Inside the chat: ask your assistant to “check my tap water with CheckYourTap”. Our connector returns your ZIP code’s measured contaminant levels — including the derived dog and cat safe levels — and, only if you ask it to, can email you the report or arrange a specialist callback.
- On the web: open CheckYourTap.com and enter your ZIP code for a free 30-second report.
Concerned about Nitrate-Nitrite in your water?
Schedule to get your water tested for nitrate-nitrite and more — a Valiant water specialist will review your results and arrange testing for your home.
Frequently Asked Questions
Is Nitrate-Nitrite in my tap water?▾
What level of Nitrate-Nitrite is safe?▾
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Related Contaminants
Check Water Quality by ZIP Code
Sources
The legal limits and health guidelines for Nitrate-Nitrite on this page come from the following public authorities:
About This Report
This water quality report is compiled from public records filed with the U.S. Environmental Protection Agency, state health departments, and the U.S. Geological Survey. Contaminant levels are evaluated against EPA federal standards and health-based guidelines from leading environmental and public health organizations. CheckYourTap is a service of Valiant Energy Solutions, a Connecticut water quality and energy services company established in 1930.
This report is general information, not medical advice or a substitute for certified laboratory testing. Talk to your pediatrician or physician about specific health concerns.
Reviewed by the CheckYourTap editorial team. Last updated July 2026