Nitrate In Drinking Water In Connecticut
What residents of Connecticut need to know about nitrate in drinking water — including how it enters water, which utilities have documented violations, and what steps to take.
Source: EPA SDWIS, Connecticut Department of Public Health (CT DPH), CDC · Last reviewed: 2025-01-01
Quick Answer
Is nitrate in drinking water a real concern in Connecticut?
Moderate — Connecticut has limited commercial agriculture but a high density of suburban septic systems, and private well users in suburban areas with older septic infrastructure can face elevated nitrate.
Is this mostly a public-water issue, a private-well issue, or both?
Primarily private well users in suburban areas with older or failing septic systems; agricultural sources are limited compared to Midwest and Southeast states.
What is the main reason residents should care?
Connecticut's suburban density means many homes are on private wells near septic systems. Older or failing septic systems can leach nitrogen-rich effluent into the surrounding soil and groundwater, elevating nitrate in nearby private wells.
Key Facts
| EPA Nitrate MCL | 10 mg/L as N |
| Primary source in CT | Older and failing septic systems near private wells in suburban communities |
| Agricultural context | Limited commercial agriculture — less agricultural nitrate than farming-intensive states |
| Private well risk | Suburban CT well users in areas with older septic infrastructure should test annually |
| State oversight | Connecticut Department of Public Health (CT DPH) |
Why This Matters in Connecticut
Connecticut has limited row-crop agriculture compared to Midwest or Southeast states, so agricultural nitrate is less of a dominant concern. However, Connecticut's suburban landscape has a high density of private wells and septic systems — particularly in Litchfield County, Tolland County, and northeastern Connecticut's more rural areas. Older and failing septic systems are a meaningful source of nitrate loading in shallow groundwater. CT DPH monitors public water systems for nitrate compliance and provides guidance on private well testing. Connecticut's geology (glacial outwash sands in some areas) can allow rapid percolation from surface sources to shallow groundwater.
Critical — Infants Under 6 Months
Do not use tap water that exceeds 10 mg/L nitrate-nitrogen to prepare infant formula or feed infants under six months. Boiling will concentrate nitrate — do not boil. Use bottled water or a certified reverse osmosis system (NSF/ANSI 58) until the issue is resolved.
Connecticut Utilities With Nitrate Violation Records
The utilities listed below have at least one nitrate violation on record in EPA's SDWIS database. Violations may be open or resolved — see individual utility pages for current status and risk level.
Regional Water Authority
Connecticut · 418,900 served
Metropolitan District Commission
Berlin,Bloomfield,Cromwell,East Granby,East Hartford,Farmington,Glastonbury,Hartford,Manchester,Newington,Portland,Rocky Hill,South Windsor,West Hartford,Wethersfield,Windsor,Windsor Locks · 390,887 served
Aquarion-eastern Fairfield County
Beacon Falls,Bridgeport,Darien,Easton,Fairfield,Greenwich,Monroe,New Canaan,Newtown,Norwalk,Redding,Ridgefield,Seymour,Shelton,Stamford,Stratford,Trumbull,Weston,Westport,Wilton · 351,756 served
Aquarion-stamford
Connecticut · 119,214 served
Waterbury Water Department
Connecticut · 107,271 served
New Britain Water Department
Berlin,Farmington,New Britain,Newington,Plainville,West Hartford · 73,534 served
Danbury Water Department
Connecticut · 62,055 served
Meriden Water Division
Berlin,Cheshire,Meriden,Southington,Wallingford · 58,441 served
Aquarion-greenwich
Connecticut · 53,297 served
Bristol Water Department
Connecticut · 52,079 served
How Nitrate Gets Into Drinking Water
Agricultural fertilizer and manure runoff
Nitrogen-based fertilizers and animal waste applied to Connecticut cropland can leach into groundwater or run off into surface water supplies. This is the dominant nitrate pathway in most agricultural regions.
Septic system effluent
Failing or poorly sited septic systems release nitrogen-rich wastewater near drinking water wells. Rural areas with high well density and aging septic infrastructure face elevated risk.
Concentrated animal feeding operations (CAFOs)
Large livestock facilities generate significant waste. Lagoon leaks and overapplication of manure to nearby fields can create localized nitrate hotspots in groundwater.
Natural geological deposits
In some regions, naturally occurring nitrogen compounds in soil and bedrock contribute background nitrate levels to groundwater independent of agricultural activity.
Who Should Pay Closest Attention
Private well users in Connecticut's rural and suburban communities — particularly in areas with older septic systems — should test for nitrate annually. Households with infants relying on private well water should test before using it for formula preparation.
Households with infants under six months
Pregnant residents
Private well owners in agricultural areas
Households near livestock operations or CAFOs
Rural residents on shallow groundwater wells
Households with older or failing septic systems nearby
How to Check Your Situation in Connecticut
- 1
Identify your water utility. Use the ZIP lookup below or browse the Connecticut utility directory on this site.
- 2
Read your utility's page on this site to see its current risk level and any open nitrate violations.
- 3
Review your utility's most recent Consumer Confidence Report (CCR) — mailed annually or available on the utility's website. It must disclose any MCL exceedances.
- 4
If you are on a private well, arrange testing at a Connecticut Department of Public Health (CT DPH)-certified lab. Your state health department maintains a list of certified labs. Annual testing is recommended in agricultural areas.
- 5
If you have an infant under six months, use bottled water or a certified RO system (NSF/ANSI 58) immediately as a precautionary measure — do not wait for test results if you are in a high-risk area.
- 6
If your utility issues a nitrate exceedance notice, follow their guidance and do not use tap water for infants until the issue is resolved.
Treatment Options
Carbon filters and boiling do not remove nitrate. Only the options below are effective.
NSF/ANSI Standard 58 — Reverse Osmosis
RO systems certified to NSF/ANSI 58 reduce nitrate by 85–95% at the point of use. Under-sink installation required. The most practical residential option for nitrate concerns.
Distillation
Distillation units effectively remove nitrate along with most other dissolved contaminants. Suitable for drinking and cooking water — not whole-house use.
Anion Exchange
Ion exchange systems designed for nitrate removal exchange nitrate ions for chloride on a resin bed. Effective as a point-of-entry system; requires periodic regeneration and monitoring.
Carbon filters do NOT remove nitrate
Standard pitcher filters, faucet filters, and under-sink carbon units — including those certified NSF/ANSI 42 or 53 — do not remove nitrate. Do not use these for nitrate reduction.
Frequently Asked Questions
Related Pages
Nitrate — National Overview
All U.S. utilities with nitrate records
Connecticut State Overview
All utilities and water quality data
Lead in Drinking Water
A separate but common concern
Reverse Osmosis Guide
Removes 85–95% of nitrate
Well Water Guide
Private well testing and safety
All Contaminants
Complete reference library
Data Sources & Provenance
All data on this page is sourced from official U.S. government or public datasets.
Find Your Utility
State Regulator
Connecticut Department of Public Health (CT DPH) ↗