Nitrate in Connecticut Drinking Water
By Alexander Snyder, Founder & Water Quality Data Lead
The U.S. EPA sets the legal limit (MCL) for Nitrate 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 has been detected in 107 Connecticut ZIP codes, above a limit or health guideline in 32. Here is what you need to know about nitrate in your drinking water and how it may affect your household.
What Is Nitrate?
Nitrate is a nitrogen compound that enters drinking water primarily from agricultural fertilizer runoff, septic system leachate, and animal waste. It is one of the most widespread groundwater contaminants in agricultural regions. The EPA maximum contaminant level is 10 milligrams per liter (as nitrogen). Nitrate is especially dangerous for infants under six months, causing methemoglobinemia (blue baby syndrome), which impairs oxygen transport in the blood.
Is Nitrate in Your Water?
Enter your Connecticut ZIP code to find out if nitrate is in your local water — and see personalized health risks for your household.
Check Your ZIP CodeHealth Effects of Nitrate
Methemoglobinemia (blue baby syndrome) in infants under 6 months — prevents blood from carrying oxygen. Long-term exposure associated with increased risk of colorectal and other cancers in adults.
Safety Guidelines
Health Guideline
10 mg/L
Source: U.S. EPA
Legal Limit (MCL)
10 mg/L
EPA Maximum Contaminant Level
Nitrate'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 Come From?
Runoff from fertilizer use; leaching from septic tanks and sewage; erosion of natural deposits; agricultural and urban runoff.
How to Reduce Nitrate in Your Water
- 1Install a point-of-use reverse osmosis system certified to NSF/ANSI Standard 58 for nitrate reduction, which typically removes 83 to 92% of nitrate from drinking water.
- 2Use an ion exchange system with a nitrate-selective resin, which is effective for whole-house treatment and can handle higher flow rates than reverse osmosis.
- 3Do not rely on standard activated carbon filters or boiling, as neither method reduces nitrate concentrations; boiling actually concentrates nitrate by evaporating water.
- 4For well water near agricultural land, test quarterly and maintain filters on the recommended schedule, as nitrate levels can fluctuate seasonally with rainfall and fertilizer application.
Who Is Most Vulnerable to Nitrate?
The safe level of nitrate 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 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 in your water?
Schedule to get your water tested for nitrate and more — a Valiant water specialist will review your results and arrange testing for your home.
Have a dog or cat?
Nitrate affects pets differently — they drink far more water per pound of body weight, and some are more sensitive than people. See the derived safe levels and the veterinary science:
Frequently Asked Questions
Is Nitrate in my tap water?▾
What level of Nitrate is safe?▾
How do I remove Nitrate from my water?▾
Related Contaminants
Check Water Quality by ZIP Code
Sources
The legal limits and health guidelines for Nitrate 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