Nitrate In Drinking Water In Illinois
What residents of Illinois 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, Illinois Environmental Protection Agency (Illinois EPA), CDC · Last reviewed: 2025-01-01
Quick Answer
Is nitrate in drinking water a real concern in Illinois?
Yes — Illinois is among the nation's top corn and soybean producers, and nitrate from agricultural tile drainage is a documented concern in both surface water supplies and groundwater.
Is this mostly a public-water issue, a private-well issue, or both?
Both — public water systems drawing from rivers in agricultural areas face seasonal nitrate spikes; private well users in central and northern Illinois farmland are also at risk.
What is the main reason residents should care?
Illinois's intensive row-crop agriculture generates significant nitrate loading via tile drainage into waterways and percolation into shallow groundwater. Illinois is the third-largest corn producer and fourth-largest soybean producer in the U.S.
Key Facts
| EPA Nitrate MCL | 10 mg/L as N |
| Illinois agriculture | #3 corn, #4 soybean producer in the US |
| Tile drainage | Subsurface drainage channels nitrate directly from fields to waterways |
| Public system risk | Systems drawing from agricultural rivers face seasonal nitrate spikes |
| State oversight | Illinois Environmental Protection Agency (Illinois EPA) |
Why This Matters in Illinois
Illinois's agricultural heartland — from the Illinois River valley through central and northern Illinois — produces enormous quantities of corn and soybeans. Tile drainage systems, which are subsurface pipes installed to drain farmland, channel nitrate-laden water directly into streams and rivers. Public water systems drawing from the Illinois River, Kaskaskia River, and other agricultural waterways can experience seasonal nitrate spikes, particularly in spring. Smaller community water systems in rural areas drawing from shallow wells have documented nitrate exceedances. Illinois EPA monitors public water systems and sets enforceable limits; private well testing is the owner's responsibility.
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.
Illinois 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.
Chicago
Chicago · 2,746,388 served
Rockford
Rockford · 147,051 served
Il American-east St Louis
East St Louis · 131,368 served
Elgin
Elgin · 114,797 served
Waukegan
Waukegan · 87,149 served
Cicero
Cicero · 83,000 served
Bloomington
Bloomington · 77,610 served
Schaumburg
Schaumburg · 75,750 served
Arlington Heights
Arlington Heights · 73,320 served
Palatine
Palatine · 70,875 served
How Nitrate Gets Into Drinking Water
Agricultural fertilizer and manure runoff
Nitrogen-based fertilizers and animal waste applied to Illinois 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
Households with infants on well water in central and northern Illinois agricultural counties should test for nitrate and consider a certified treatment system. Communities served by small water systems drawing from shallow agricultural-area wells should review recent water quality reports.
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 Illinois
- 1
Identify your water utility. Use the ZIP lookup below or browse the Illinois 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 Illinois Environmental Protection Agency (Illinois EPA)-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
Illinois 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.
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Illinois Environmental Protection Agency (Illinois EPA) ↗