How many water violations are in Maricopa County?

Maricopa County has 30,745 total drinking water violations across 215 water systems, of which 1,092 are health-based violations. 97.2% of systems have at least one violation.

How many people get water from Maricopa County systems?

Water systems in Maricopa County serve approximately 4,392,896 people through 215 public water systems.

Has PFAS been detected in Maricopa County water?

Under EPA UCMR5, 17 of 42 tested systems in Maricopa County had at least one PFAS detection (40.5% of the UCMR5-tested subset - not of all 215 SDWIS systems).

What types of water sources supply Maricopa County?

Water systems in Maricopa County use GW (190 systems), SW (25 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. 3.6% of Maricopa County's violations are health-based. Among counties with any SDWIS violations, this extract puts Maricopa County in the lower health-based share band. Not all violations indicate immediate health risk, but they require corrective action.

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

According to EPA SDWIS county population served used on /counties, Maricopa County ranks #5 of 3,254 counties by people served, and #1 of 15 counties in Arizona. Ordinals use the same total_population DESC sort as the counties directory. See /methodology#corpus-placement.

Counties → Arizona

Maricopa County, Arizona

Compiled by PlainWater · May 15, 2026

SDWIS compliance plate

Sheet AZ013 · Maricopa County 215 sys · 30,745 viol · #5/3254

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

VIOL-SEVERE 97.2% flagged
HEALTH-LOW 3.6% health
RANK-TOP #5/3254
PHOTO-FINISH ±0.3 pp
PFAS-MID 40.5% detect
SRC-GW GW lead 88%
SYS-LARGE 215 systems
BOOK-FULL 7/7 fields

Nearest flagged-rate peer: Mohave County (+ 0.3 pp flagged-rate)

According to EPA SDWIS county population served used on /counties, Maricopa County ranks #5 of 3,254 counties by people served, and #1 of 15 counties in Arizona. See methodology · corpus placement.

Maricopa County standing, mid-flagged corpus third

Flagged-system rate 97.2% is in the corpus middle third (≤ 100.0% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 3.6% is health-based share at or below the lower third (≤ 10.3%) . UCMR5 detect rate 40.5% is UCMR5 detect rate above the tested-pool upper third (> 33.3%) . Population served ranks #5 of 3,254 · #1 of 15 in Arizona.

Water Systems

System Name	Population	Violations	PFAS
Phoenix City Of	1,695,000	84	Detected
Mesa City Of	466,000	1,739	Detected
Gilbert, Town Of	247,600	1,235	Detected
Chandler City Of	247,328	851	Detected
Scottsdale City Of	241,361	963	Detected
Glendale City Of	234,766	645	Detected
Peoria City Of	187,676	2,461	Detected
Tempe City Of	165,000	339	Detected
Epcor - Agua Fria	127,718	525	Clean
Queen Creek Town Of	95,502	494	Clean
Avondale City Of	83,001	242	Detected
Liberty Water Lpsco	50,770	271	Detected
Goodyear Water Department	50,001	351	Detected
Surprise City of - Mountain Vista	40,007	419	Clean
El Mirage City Of	39,884	1,007	Detected
Epcor - Sun City	38,016	308	Clean
City of Buckeye - Valencia Town Division	30,377	341	Clean
Epcor - Chaparral City	26,026	492	Clean
Epcor - Sun City West	25,796	110	Clean
Desert Oasis	23,963	54	Clean
Epcor - Anthem	23,826	160	Clean
Pima Utilities	20,000	259	Clean
Arizona Water Co - White Tanks	18,858	26	Detected
City of Buckeye Sonora - Sundance	15,783	137	Clean
Epcor - North East Agua Fria	14,723	49	Clean
Epcor - Paradise Valley/Scottsdale	14,107	94	Clean
Festival Ranch	10,313	52	Clean
City of Buckeye Tartesso Water System	10,123	62	-
Tolleson City Of	9,300	120	Detected
Beardsley Water Company 1	9,002	95	Clean
Usaf Luke Air Force Base	8,440	759	Detected
Buckeye City Of	7,008	262	Clean
Sunrise Water Company	6,490	62	Clean
Wickenburg Town Of	6,481	233	Clean
Rose Valley Water Company	6,202	55	Clean
Valley Utilities Water Company Glendale	5,940	72	Detected
Cave Creek Water	5,895	258	Clean
Epcor- Rio Verde	5,330	141	Clean
Epcor - Tierra del Rio	4,868	3	Clean
Phoenix International Raceway	4,500	66	Detected
Aspc Lewis Complex Water System	4,300	594	Clean
Desert Hills Water	4,220	125	Clean
Carefree Water Company	3,894	52	Clean
Palo Verde Nuclear Generating Station	3,000	40	-
McPrd - Lake Pleasant	2,950	16	-
Chandler Heights Citrus Irrigation Dist	2,620	86	-
Clearwater Utility Company Inc	2,175	307	-
Gila Bend Town Of	1,922	282	-
Sheraton Phoenix Downtown	1,804	44	-
Ruth Fisher School	1,800	100	-

Compare beyond Arizona

Mid-flagged peers for Maricopa County

Cross-state counties nearest Maricopa County on flagged-system share (97.2%) and cumulative violation count (30,745). 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.