How many water violations are in DuPage County?

DuPage County has 15,779 total drinking water violations across 207 water systems, of which 540 are health-based violations. 60.4% of systems have at least one violation.

How many people get water from DuPage County systems?

Water systems in DuPage County serve approximately 861,775 people through 207 public water systems.

Has PFAS been detected in DuPage County water?

Under EPA UCMR5, 4 of 32 tested systems in DuPage County had at least one PFAS detection (12.5% of the UCMR5-tested subset - not of all 207 SDWIS systems).

What types of water sources supply DuPage County?

Water systems in DuPage County use GW (148 systems), SW (59 systems) as their primary water sources.

Are health-based violations serious?

Health-based violations indicate that drinking water exceeded Maximum Contaminant Levels (MCLs) set by the EPA or failed treatment technique requirements. 3.4% of DuPage County's violations are health-based. Among counties with any SDWIS violations, this extract puts DuPage County in the lower health-based share band. Not all violations indicate immediate health risk, but they require corrective action.

Where does DuPage County sit among U.S. counties for water-system population?

According to EPA SDWIS county population served used on /counties, DuPage County ranks #71 of 3,254 counties by people served, and #2 of 102 counties in Illinois. Ordinals use the same total_population DESC sort as the counties directory. See /methodology#corpus-placement.

Counties → Illinois

DuPage County, Illinois

Compiled by PlainWater · May 15, 2026

SDWIS compliance plate

Sheet IL043 · DuPage County 207 sys · 15,779 viol · #71/3254

VIOL-SEVERE · HEALTH-LOW · RANK-TOP · PHOTO-FINISH · PFAS-LOW · SRC-GW · SYS-LARGE · BOOK-FULL

VIOL-SEVERE 60.4% flagged
HEALTH-LOW 3.4% health
RANK-TOP #71/3254
PHOTO-FINISH ±0.7 pp
PFAS-LOW 12.5% detect
SRC-GW GW lead 71%
SYS-LARGE 207 systems
BOOK-FULL 7/7 fields

Nearest flagged-rate peer: St. Clair County (+ 0.7 pp flagged-rate)

According to EPA SDWIS county population served used on /counties, DuPage County ranks #71 of 3,254 counties by people served, and #2 of 102 counties in Illinois. See methodology · corpus placement.

DuPage County standing, lower-flagged corpus third

Flagged-system rate 60.4% is at or below the corpus lower third (≤ 92.7% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 3.4% is health-based share at or below the lower third (≤ 10.3%) . UCMR5 detect rate 12.5% is UCMR5 detect rate in the tested-pool middle third (≤ 33.3%) . Population served ranks #71 of 3,254 · #2 of 102 in Illinois.

Water Systems

System Name	Population	Violations	PFAS
Naperville	156,406	5	Clean
Wheaton	53,970	11	Clean
Downers Grove	49,425	36	Clean
Elmhurst	45,000	47	Detected
Lombard	44,476	13	Clean
Carol Stream	39,854	23	Detected
Addison	38,017	19	Clean
Woodridge	33,566	28	Clean
Glendale Heights	33,176	24	Clean
Glen Ellyn	28,850	18	Clean
West Chicago	25,166	148	Clean
Lisle	24,233	23	Clean
Westmont	24,161	37	Clean
Roselle	22,897	42	Clean
Villa Park	22,263	41	Clean
Bloomingdale	22,018	79	Clean
Darien	21,751	15	Clean
Bensenville	18,537	59	Clean
Hinsdale	17,900	11	Clean
Wood Dale	14,012	12	Clean
Warrenville	12,350	201	Clean
Burr Ridge	11,192	20	Clean
Winfield	9,835	43	Clean
Itasca	9,506	36	Detected
Oak Brook	9,400	54	Clean
Willowbrook	9,000	33	Clean
Clarendon Hills	8,702	14	Clean
Southeast Regional Water Facility	6,940	2	Clean
IL American-Valley View	6,721	3	Detected
IL American-Dupage Utility	6,613	15	-
Aqua Illinois-Oak Brook	5,361	1	-
IL American-Liberty Ridge West	3,307	12	Clean
Glen Ellyn Heights Subdivision	1,931	15	-
Steeple Run Sbdv	1,931	10	-
IL American-Arrowhead	1,581	6	-
Oakbrook Terrace	1,440	4	-
York Township Water System	1,423	172	-
IL American-Country Club	1,014	1	Clean
Liberty Park Homeowners Association	950	32	-
Prairie Path Water Company-Clarendon	850	27	Clean
Community Fellowship Church	800	1	-
North Regional Water Fac	770	153	-
IL American-Lombard Heights	679	1	-
Wayne School	625	107	-
Indian Knoll School Dist 33	600	292	-
Marianjoy Rehab Hospital	500	156	-
Hobson Valley Water System	400	2	-
IL American-Liberty Ridge East	320	9	-
Living Hope Bible Church	300	0	-
Blackwell Youth Camp Well Dw-002	300	0	-

Compare beyond Illinois

Lower-flagged peers for DuPage County

Cross-state counties nearest DuPage County on flagged-system share (60.4%) and cumulative violation count (15,779). In-state neighbours stay on the compliance plate above.

Similar flagged-system rate

Nearest cross-state counties by % of SDWIS systems with at least one violation on record.

4 peers

Similar violation load

Nearest cross-state counties by cumulative SDWIS violation count (all systems in the county).

4 peers

Read our methodology · Check your water system - how this data is sourced, computed, and verified.

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater

Compiled by PlainWater, Drinking Water Quality Editorial Process · May 15, 2026

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This page draws directly on EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.