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Counties → California

Orange County, California

SDWIS compliance plate

Sheet CA059 · Orange County 46 sys · 507 viol · #9/3254

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

  • VIOL-SEVERE 89.1% flagged
  • HEALTH-MID 21.3% health
  • RANK-TOP #9/3254
  • PHOTO-FINISH ±0.2 pp
  • PFAS-HIGH 60.0% detect
  • SRC-SW SW lead 78%
  • SYS-MID 46 systems
  • BOOK-FULL 7/7 fields

Nearest flagged-rate peer: Siskiyou County ( -0.2 pp flagged-rate)

According to EPA SDWIS county population served used on /counties, Orange County ranks #9 of 3,254 counties by people served, and #3 of 58 counties in California. See methodology · corpus placement.

Orange County standing, lower-flagged corpus third

Flagged-system rate 89.1% is at or below the corpus lower third (≤ 92.7% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 21.3% is health-based share in the middle third (≤ 24.5%) . UCMR5 detect rate 60.0% is UCMR5 detect rate above the tested-pool upper third (> 33.3%) . Population served ranks #9 of 3,254 · #3 of 58 in California.

Flagged-rate neighbourhood around Orange County

Lowest/highest poles plus in-state counties nearest Orange County on % of SDWIS systems with ≥1 violation. Full ladder: /counties.

0% 20% 40% 60% 80% 100% Alpine · lowest Siskiyou · near Orange · this county Sutter · highest 70% 88.4% 88.9% 88.9% 89.1% 89.8% 97.1%

Source: EPA SDWIS (county aggregates) As of 2026-05-15

Water Systems

System Name Population Violations PFAS
Irvine Ranch Water District 444,800 12 Detected
City of Anaheim 348,593 5 Detected
City of Santa Ana 310,539 20 Detected
City of Huntington Beach 201,000 9 Detected
City of Garden Grove 174,226 0 Detected
Moulton Niguel Water District 170,236 0 Clean
Santa Margarita Water District 168,289 2 Clean
City of Fullerton 139,461 14 Detected
City of Orange 120,770 6 Detected
Golden State WC - West Orange County 114,379 0 Detected
Mesa Water District 110,000 4 Clean
City of Westminster 90,911 13 Detected
Yorba Linda Water District 84,292 4 Detected
City of Buena Park 81,998 12 Detected
City of Newport Beach 68,572 7 Clean
City of Tustin 66,600 17 Detected
City of la Habra 63,118 101 Clean
City of Fountain Valley 56,747 8 Detected
El Toro Water District 51,800 1 Detected
City of San Clemente 51,545 4 Clean
Golden State WC - Placentia/Yorba Linda 50,381 0 Detected
City of Brea 48,479 3 Clean
South Coast Water District 41,118 4 Detected
Santa Margarita Water District-Id9 39,684 22 Clean
City of Seal Beach 24,937 4 Clean
Laguna Beach County WD 18,404 2 Clean
City of la Palma 15,948 8 Clean
Trabuco Canyon Water District 13,659 16 Clean
Golden State WC - Cowan Heights 6,997 1 Detected
Serrano Water District 5,659 8 Detected
Joint Regional Water Supply System 3,947 0 -
East Orange County WD - Rz 3,464 3 -
Knott S Berry Farm 3,000 10 -
Eastside Water Association 2,000 11 -
Los Alamitos Race Course 1,600 18 -
Smwd-Nichols Institute 1,600 2 -
Midway City Mutual WC 1,305 32 -
South Midway City Mutual Water Co. 891 12 -
Canyon RV Park 294 10 -
Caspers Regional Wilderness Park 215 6 -
Hynes Estates Mutual Water Co. 168 21 -
Page Avenue Mutual Water Company 119 24 -
Liberty Park Water Association 85 19 -
Lazy W Ranch Water System 63 5 -
East Orange County WD - Wz 0 6 -
San Juan Basin Authority 0 21 -

Compare beyond California

Lower-flagged peers for Orange County

Cross-state counties nearest Orange County on flagged-system share (89.1%) and cumulative violation count (507). 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

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.