How many water violations are in Los Angeles County?

Los Angeles County has 3,972 total drinking water violations across 276 water systems, of which 1,260 are health-based violations. 93.1% of systems have at least one violation.

How many people get water from Los Angeles County systems?

Water systems in Los Angeles County serve approximately 10,109,089 people through 276 public water systems.

Has PFAS been detected in Los Angeles County water?

Under EPA UCMR5, 63 of 117 tested systems in Los Angeles County had at least one PFAS detection (53.8% of the UCMR5-tested subset - not of all 276 SDWIS systems).

What types of water sources supply Los Angeles County?

Water systems in Los Angeles County use GW (164 systems), SW (112 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. 31.7% of Los Angeles County's violations are health-based. Among counties with any SDWIS violations, this extract puts Los Angeles County in the higher health-based share band. Not all violations indicate immediate health risk, but they require corrective action.

Counties → California

Los Angeles County, California

Compiled by PlainWater · May 15, 2026

SDWIS compliance plate

Sheet CA037 · Los Angeles County 276 sys · 3,972 viol · #1/3254

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

VIOL-SEVERE 93.1% flagged
HEALTH-MID 31.7% health
RANK-TOP #1/3254
PHOTO-FINISH ±0.1 pp
PFAS-HIGH 53.8% detect
SRC-GW GW lead 59%
SYS-LARGE 276 systems
BOOK-FULL 7/7 fields

Nearest flagged-rate peer: El Dorado County ( -0.1 pp flagged-rate)

According to EPA SDWIS county population served used on /counties, Los Angeles County ranks #1 of 3,254 counties by people served, and #1 of 58 counties in California. See methodology · corpus placement.

Los Angeles County standing, mid-flagged corpus third

Flagged-system rate 93.1% is in the corpus middle third (≤ 100.0% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 31.7% is health-based share above the upper third (> 24.5%) . UCMR5 detect rate 53.8% is UCMR5 detect rate above the tested-pool upper third (> 33.3%) . Population served ranks #1 of 3,254 · #1 of 58 in California.

Water Systems

System Name	Population	Violations	PFAS
Los Angeles-City, Dept. of Water & Power	3,875,566	33	Clean
Long Beach Utilities Department	466,772	6	Clean
Santa Clarita Valley Water Agency	294,090	4	Detected
Gswc - Southwest	277,740	11	Clean
San Gabriel Valley Water Co.-El Monte	248,000	13	Detected
Los Angeles Cwwd 40 Reg 4 & 34 Lancaster	208,129	11	Clean
Glendale-City, Water Dept.	188,784	2	Detected
Suburban Water Systems-San Jose	168,843	10	Detected
Pasadena Water and Power	164,344	8	Clean
California Water Service Co. - Ela	152,474	13	Detected
Pomona - City, Water Dept.	151,713	14	Detected
California Water Service Co. - Dominguez	143,996	19	Detected
Palmdale Water Dist.	126,804	12	Detected
Azusa Light and Water	110,044	2	Detected
Downey - City, Water Dept.	108,816	16	Detected
Torrance-City, Water Dept.	106,183	57	Clean
Burbank-City, Water Dept.	105,603	16	Detected
Walnut Valley Water District	100,941	5	Clean
California Water Service Co. - Herm/Redo	96,853	10	Clean
Santa Monica-City, Water Division	89,947	3	Detected
Inglewood- City, Water Dept.	80,824	16	Detected
City of Alhambra	79,776	8	Clean
South Gate-City, Water Dept.	76,443	127	Detected
Compton-City, Water Dept.	74,877	20	Detected
Liberty Utilities - Bellflower-Norwalk	72,624	4	Detected
Las Virgenes MWD	72,602	9	Clean
California Water Service Co. - Palos Ver	71,452	6	Clean
Valley County Water Dist.	68,871	8	Clean
Lynwood-City, Water Dept.	66,967	20	Detected
Lakewood - City, Water Dept.	66,135	6	Detected
Suburban Water Systems-Whittier	66,045	4	Detected
Gswc - Florence/Graham	63,500	2	Clean
Monterey Park-City, Water Dept.	62,183	9	Detected
Suburban Water Systems-la Mirada	56,793	0	Detected
Gswc-San Dimas	56,538	5	Detected
Paramount - City, Water Dept.	55,200	7	Clean
Gswc - Bell, Bell Gardens	54,877	8	Detected
Rowland Water District	54,660	4	Detected
City of Arcadia	51,361	17	Detected
Gswc - Artesia	50,375	5	Detected
Whittier-City, Water Dept.	49,954	0	Clean
Glendora-City, Water Dept.	49,934	4	Clean
Cal/Am Water Company - San Marino	47,995	2	Detected
Cerritos - City, Water Dept.	47,475	0	Detected
Bellflower - Somerset MWC	46,300	2	Detected
Hawthorne-City Water Dept.	44,718	8	Clean
Gswc - Norwalk	43,176	3	Detected
Pico Rivera - City, Water Dept.	40,600	17	Detected
Beverly Hills-City, Water Dept.	40,121	91	Clean
Gswc - Claremont	39,730	6	Detected

Compare beyond California

Mid-flagged peers for Los Angeles County

Cross-state counties nearest Los Angeles County on flagged-system share (93.1%) and cumulative violation count (3,972). 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.