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Counties → California

County profile · EPA SDWIS + UCMR5

Alameda County, California

27 SDWIS-listed public water systems serve 2,249,634 people in Alameda County. Violation rates use that full inventory; PFAS rates use only the UCMR5-tested subset.

27
SDWIS water systems Middle third of counties
275
Total violations Lower third of counties
70.4%
SDWIS systems w/ a violation Lower third of counties
37.5%
UCMR5 PFAS rate (8 tested) Upper third of counties with tests

SDWIS compliance plate

Sheet CA001 · Alameda County 27 sys · 275 viol · #16/3254

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

  • VIOL-SEVERE 70.4% flagged
  • HEALTH-LOW 12.7% health
  • RANK-TOP #16/3254
  • PHOTO-FINISH ±0.4 pp
  • PFAS-MID 37.5% detect
  • SRC-SW SW lead 56%
  • SYS-SMALL 27 systems
  • BOOK-FULL 7/7 fields

Nearest flagged-rate peer: Alpine County ( -0.4 pp flagged-rate)

According to EPA SDWIS county population served used on /counties, Alameda County ranks #16 of 3,254 counties by people served, and #6 of 58 counties in California. See methodology · corpus placement.

Alameda County standing, lower-flagged corpus third

Flagged-system rate 70.4% is at or below the corpus lower third (≤ 92.7% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 12.7% is health-based share in the middle third (≤ 24.5%) . UCMR5 detect rate 37.5% is UCMR5 detect rate above the tested-pool upper third (> 33.3%) . Population served ranks #16 of 3,254 · #6 of 58 in California.

Flagged-rate neighbourhood around Alameda County

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

0% 20% 40% 60% 80% 100% Alpine · lowest Lassen · near Mendocino · near 70% 70.4% 72.7% 74.9% 77.6% 97.1%

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

Water Systems

System Name Population Violations PFAS
East Bay MUD 1,442,800 14 Detected
Alameda County Water District 344,000 9 Clean
City of Hayward 162,954 6 Clean
Dublin San Ramon Services District 98,776 4 Clean
City of Pleasanton 76,689 4 Detected
California Water Service - Livermore 60,414 2 Detected
City of Livermore 38,892 2 Clean
Lawrence Livermore National Lab Site 200 10,870 0 Clean
Ebrpd - del Valle Regional Park 9,024 28 -
Chp - Mission Grade Scales 1,800 2 -
Alameda Point 1,400 0 -
Castlewood Domestic Water System 524 6 -
Trailer Haven Mobile Home Park 459 4 -
Town of Sunol - Sfpuc 281 1 -
Sunol Super Stop 155 0 -
Ebrpd - Sunol Regional Wilderness 91 0 -
Usbr-Sldmwa - Cvp Jones Pumping Plant 90 0 -
Alameda County Fairgrounds 82 20 -
Purple Orchid Resort Spa 52 0 -
Norris Canyon Property Owners Assn 50 111 -
Mountain House School 50 13 -
Ebrpd - Piedmont Stables 45 0 -
Zone 7 Water Agency 40 6 -
Rancho los Mochos-Bsa Camp 38 2 -
Rivers End Marina 32 31 -
Mountain House Bar 25 10 -
Sfpuc-Pleasanton Wells 1 0 -

Compare beyond California

Lower-flagged peers for Alameda County

Cross-state counties nearest Alameda County on flagged-system share (70.4%) and cumulative violation count (275). 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. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.