County water report

DuPage County Water Report

Drinking-water compliance, watershed health, monitoring records, and river conditions for DuPage County, Illinois.

Water grade

Water score

71.3

State rank

#14

of 102

Health violations

EPA SDWIS, 5-year lookback

Watershed impaired

53.8%

692 water bodies assessed

Monitoring sites

2,229 recent measurements

Live streamflow

19%

CHICAGO SANITARY AND SHIP CANAL NR LEMONT, IL

Water at a glance

Key Water Indicators for DuPage County

EPA SDWIS

Safety Grade

Score: 71.3 / 100

EPA SDWIS

Active Violations

5-year health-based lookback

EPA ATTAINS

Watershed Health

54% impaired

692 bodies assessed

USGS NWIS

Streamflow Snapshot

19% of mean

CHICAGO SANITARY AND SHIP CANAL NR LEMONT, IL

EPA WQP

Monitoring Sites

2,229 recent readings

Source: EPA SDWIS · Safe Drinking Water Information System

Drinking Water Compliance

Compliance grade

Based on EPA SDWIS compliance history.

Water score

Higher scores indicate cleaner recent compliance records.

71.3/100

Health violations

Health-based violations

Violations per 100K served

0.4

Population-normalized SDWIS rate

Data center water stress

DuPage County has 26 facilities in the DCWSI dataset.

ByCounty's DCWSI ranks this county #22 nationally by combining its water score with mapped data center density.

DCWSI

80.6

0-100 index

Facility count

94.5 density percentile

Discharge estimate

Not reported

EPA CWA fields where available

Water vs median

+21.3

Compared with US county median

Named operators

CentersquareCyrusOneUChicago Argonne LLCEdgedElement Critical

Mapped facilities

360 TCS LLC
LOMBARD
EPA ECHO
4513 WESTERN AVENUE LLC
LISLE
EPA ECHO
Centersquare Elk Grove Village Data Center Campus ORD2
Elk Grove Village · Centersquare
OSM
Centersquare Lisle ORD4 Data Center
Lisle · Centersquare
OSM
CHICAGO ENTERPRISE LLC
WOOD DALE
EPA ECHO
CLEARBLUE TECHNOLOGIES/OAKBROOK INC
OAK BROOK
EPA ECHO

20 more mapped facilities included in the county score.

See the DuPage County data-center report Review methodology

Data Center Water Budget Calculator

Estimate daily water use for a hypothetical facility in DuPage County.

Facility size: 100 MW

1 MW1,000 MW

Cooling type

Utilization: 70%

40%100%

799K gallons/dayModerate Impact

Your facility would use 11.8% of this county's industrial water baseline — manageable but worth monitoring against drought trends.

11.8% of county industrial baseline5.99 Mgal/day remaining headroom

Based on USGS 2020 water-use data and EPA-standard cooling intensity constants. Not a substitute for site-specific water rights analysis.

Editorial analysis

Understanding DuPage County’s Water

Drinking Water Quality Overview

EPA SDWIS

DuPage County earns an A grade for drinking water quality, scoring 71.3 out of 100. Over the past five years, EPA SDWIS records 3 health-based violations — a small cluster that warrants attention.

Watershed Conditions

EPA ATTAINS

Under the Clean Water Act §303(d), EPA ATTAINS tracks whether waterways meet quality standards for drinking, recreation, and aquatic life (reporting cycle: 2022). A substantial 53.8% of assessed waterways are impaired (372 of 692 water bodies) across DuPage County's watersheds. The leading impairment causes are phosphorus, total and total suspended solids (tss). Impairment does not mean tap water is unsafe — it measures ambient waterway conditions upstream of treatment, not finished drinking water.

River & Streamflow Status

USGS NWIS

USGS NWIS gauge data (as of 2026-05-14T12:39:00.000-06:00) puts CHICAGO SANITARY AND SHIP CANAL at 529.0 cfs — well below its long-term average at 19% of mean — low-flow conditions worth noting for water-dependent ecosystems. Streamflow is a leading indicator of drought stress, sediment load, and dilution capacity: low flows concentrate pollutants and warm water temperatures, stressing aquatic life and, in surface-water-dependent systems, the source water quality for treatment plants.

Monitoring Network

EPA WQP

EPA's Water Quality Portal (WQP) aggregates monitoring data from federal, state, and tribal agencies. DuPage County has limited coverage with 7 active monitoring sites with 2,229 recent measurements on record. Predominant monitoring categories include inorganics, minor, metals and physical. More monitoring sites generally indicate greater scientific attention to local water conditions — and provide the baseline data that regulators use to set future impairment listings.

Editorial advisory

What the data suggests for DuPage County

Water Verdict

DuPage County receives a good water quality assessment with a grade of A and a score of 71.3 out of 100. While the water supply is generally safe, occasional monitoring gaps or minor contaminant detections may occur.

Violation Context

DuPage County has recorded 3 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 0.4 violations per 100,000 people served, this rate is relatively low compared to many U.S. counties.

Consumer Guidance

Tap water in DuPage County earns a Grade A overall with a small number of isolated health violations in the recent record. DuPage County's drinking-water compliance score is 71.3 out of 100. The violation rate for DuPage County is 0.4 per 100,000 people served. These violations were likely resolved quickly; Grade A reflects a strong multi-year compliance trend. Reviewing the most recent Consumer Confidence Report will show exactly which systems were affected and what corrective action was taken. There are 7 active water-quality monitoring sites in DuPage County. Phosphorus, Total is the leading impairment cause in DuPage County's watershed. A pipeline streamflow snapshot from the CHICAGO SANITARY AND SHIP CANAL gauge is also available on this page.

Regional Context

DuPage County has better water quality than the average county in Illinois. Its water score is 23.5 points higher than the state average, indicating stronger water system performance relative to neighboring counties.

Advisory text summarizes county-level public records and is not a replacement for your utility's current Consumer Confidence Report or direct local notices.

Contaminants & Resources

Key issues flagged in DuPage County's water environment

Watershed Impairment Causes (EPA ATTAINS)

1
Phosphorus (excess nutrients)
Impairment cause per EPA Clean Water Act §303(d) assessment
2
Total Suspended Solids (Tss)
Impairment cause per EPA Clean Water Act §303(d) assessment
3
Mercury
Impairment cause per EPA Clean Water Act §303(d) assessment

Source: EPA ATTAINS · Reporting cycle 2022

Official EPA Resources for DuPage County

EPA How's My Waterway

Interactive watershed health data for DuPage County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for DuPage County

Consumer Confidence Reports (IL)

Annual water quality reports from utilities in Illinois

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

53.8%

372 of 692 assessed

Moderate concern

Top Impairment Causes

1
PHOSPHORUS, TOTAL
2
TOTAL SUSPENDED SOLIDS (TSS)
3
MERCURY

Source: EPA ATTAINS · Reporting cycle 2022

Impairment is determined under the Clean Water Act §303(d): a water body is impaired when it fails to meet state-defined quality standards for designated uses (drinking, recreation, aquatic life). Assessment coverage varies by state; counties without assessed water bodies are not shown.

Past 5 years

Water Quality Monitoring

Monitoring Sites

Active in the past 5 years

Measurements Recorded

2.2K

2,229 total readings

Most Measured

Inorganics, Minor, Metals
Physical
Inorganics, Major, Metals

Categories measured most frequently

Data from the EPA Water Quality Portal (WQP), aggregating monitoring records from federal, state, and tribal sources. Each measurement represents a single sample analyzed for a specific characteristic (e.g., E. coli, pH, dissolved oxygen, nitrogen).

Live USGS Streamgage

River & Stream Conditions

Current Discharge

529cfs

May 14, 6:39 PM UTC

vs Long-Term Average

19%

Well below typical

Primary Streamgage

CHICAGO SANITARY AND SHIP CANAL NR LEMONT, IL

USGS site: 05536890
Drainage area: 738 sq mi
Long-term mean: 2,781 cfs

One representative streamgage (the one with the largest drainage area in the county). Many counties have multiple gauges; this view summarizes the primary one. The long-term mean is the full-record annual average; the percent-of-typical value compares the latest reading against that average.

Free tool

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Water Cost Estimate

Household size

3 people · ~225 gal/day

Filter type

Annual Total

$558

Monthly

$47

Water Bill

$558/yr

Filter Cost

$0/yr

Safety Grade for DuPage County:C — Moderate

Some violations or watershed impairment detected.

Estimates use the national average residential water rate ($0.0068/gal, EPA/AWWA 2023) and EPA WaterSense per-person consumption baseline (75 gal/person/day). Actual bills vary by utility, usage tier, and local infrastructure fees. For informational purposes only.

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Frequently Asked Questions

What is the water quality in DuPage County, Illinois?

DuPage County, Illinois has a drinking-water quality grade of A with a score of 71.3/100, based on EPA SDWIS compliance data. The county has 3 health-based drinking water violations over the past 5 years. Watershed health, monitoring records, and streamflow snapshots are reported separately on this page.

Are there any water violations in DuPage County?

DuPage County has 3 health-based drinking water violations recorded by the EPA over the past 5 years. Health-based violations indicate instances where contaminant levels exceeded EPA Maximum Contaminant Levels (MCLs). Violations may have been resolved — check with your local water utility for current status.

How healthy are the watersheds in DuPage County?

EPA ATTAINS assessments under Clean Water Act §303(d) indicate 53.8% of DuPage County's 692 assessed water bodies are classified as impaired (372 impaired). The top reported causes are PHOSPHORUS, TOTAL, TOTAL SUSPENDED SOLIDS (TSS), MERCURY. Impairment means the water body fails to meet state quality standards for at least one designated use — drinking water source, recreation, aquatic life, or fish consumption. Note: watershed impairment doesn't always translate to tap-water issues; treatment plants can remove most regulated contaminants.

How much water-quality monitoring happens in DuPage County?

EPA's Water Quality Portal records 2,229 measurements from 7 monitoring sites in DuPage County over the past five years. The most frequently measured characteristic groups are Inorganics, Minor, Metals, Physical, Inorganics, Major, Metals. Each measurement is a single sample analyzed for one characteristic (E. coli, pH, dissolved oxygen, etc.). High monitoring density means more scientific evidence behind any reported signal — it does not by itself indicate water quality.

What's happening with rivers in DuPage County right now?

DuPage County's primary USGS streamgage on the CHICAGO SANITARY AND SHIP CANAL has a pipeline snapshot of 529 cubic feet per second — 19% of the long-term mean of 2,781 cfs. This is well below typical — often a signal of drought stress on source water. For the latest gauge feed, visit waterdata.usgs.gov.

How does DuPage County water compare to the Illinois average?

DuPage County's SDWIS water quality score of 71.3/100 is higher than the Illinois state average of 47.8. The average water quality grade across Illinois is D, based on data from 102 counties with available SDWIS data.

Is tap water safe to drink in DuPage County?

Based on EPA SDWIS data, DuPage County has a water quality grade of A (71.3/100). This indicates good to excellent water quality with strong SDWIS compliance. The grade speaks to the public water system, not the watershed — for watershed-level concerns, see the Watershed Health zone. For the most up-to-date information, contact your local water utility or review your Consumer Confidence Report (CCR).

Does DuPage County have clean drinking water?

DuPage County has 3 health-based drinking water violations according to EPA records. With a water quality score of 71.3/100 and grade A, the county's drinking water has had some compliance issues but continues to be monitored. Note: drinking-water compliance speaks to the public water system, not necessarily to the watershed itself — check the Watershed Health zone for ATTAINS §303(d) data.

How does DuPage County rank for water quality in Illinois?

DuPage County ranks #14 out of 102 counties in Illinois by SDWIS water quality score (1 = best). With a score of 71.3/100, it falls in the top third of counties statewide. The ranking reflects EPA SDWIS compliance only — not watershed impairment, monitoring density, or streamflow, which are tracked separately on this page.

Counties with Similar Water Quality

Cook County

Illinois

70.8

Water score

Kane County

Illinois

70.1

Water score

Kendall County

Illinois

69.3

Water score

Data Sources

Drinking-water compliance data from the EPA Safe Drinking Water Information System (SDWIS) via the ECHO enforcement database. Scores reflect compliance history and health-based violation counts.

Watershed health and impaired-waterway data from the EPA ATTAINS Clean Water Act §303(d) assessments, state-reported and EPA-finalized.

Water-quality monitoring counts from the EPA Water Quality Portal (WQP), federated USGS, EPA, and state agency sampling records over a rolling 5-year window.

Live streamflow from the USGS National Water Information System (NWIS), continuous discharge measurements from the largest-drainage gauge in each county, compared against the full-record long-term annual mean.

Disclaimer: This data is informational only. It is not health, legal, or professional advice. For concerns about your specific water supply, contact your local water utility.

By Evan Brooks, Data EditorUpdated May 14, 2026Reviewed by Evan Brooks, Data Editor

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