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Updated 2026-10-15
County water report

Los Angeles County Water Quality: 61 Cities Ranked by the Records

Los Angeles County, California: 61 city reports built from EPA and utility records. A county has many suppliers; each city shows the system that serves it.

Find my systemOpen on the mapPrivate wells in Los Angeles County
Across the county's systems

Highest result for each contaminant

One row per contaminant: the highest result any system in the county reported, against its limit. Open a row for the systems behind it.

Perfluorooctanesulfonic acid (PFOS)Detected in 27 systems of 61 tested4.0 ng/L federal MCL (2024) · US EPAHighest44 ng/L
LithiumDetected in 39 systems of 61 tested10 µg/L EPA health reference level (screening, not a legal limit) · US EPAHighest100 µg/L
Perfluorooctanoic acid (PFOA)Detected in 20 systems of 61 tested4.0 ng/L federal MCL (2024) · US EPAHighest16 ng/L
Water hardnessDetected in 6 systemsAesthetic, no federal health limit · USGSHighest14.3 gpg
Perfluorohexanesulfonic acid (PFHxS)Detected in 22 systems of 61 tested10 ng/L federal MCL (2024) · US EPAHighest8.9 ng/L
Lead (90th percentile)Detected in 18 systems of 61 tested15 µg/L federal action level · US EPAHighest9 µg/L
Total trihalomethanes (TTHM)Detected in 2 systems80 ppb federal MCL · US EPAHighest46.2 ppb
CopperDetected in 1 system1.3 mg/L (action level) · US EPAHighest0.529 mg/L
10 more contaminants detectedShow
ArsenicDetected in 1 system0.010 mg/L · US EPAHighest0.003 mg/L
Haloacetic acids (HAA5)Detected in 2 systems60 ppb federal MCL · US EPAHighest13.4 ppb
FluorideDetected in 1 system4.0 mg/L · US EPAHighest0.7 mg/L
NitrateDetected in 1 system10 mg/L · US EPAHighest0.4 mg/L
Perfluorobutanesulfonic acid (PFBS)Detected in 14 systems of 61 tested2,000 ng/L EPA health advisory (screening, not a legal limit) · US EPAHighest16.9 ng/L
Perfluorohexanoic acid (PFHxA)Detected in 16 systems of 61 tested400,000 ng/L Michigan EGLE state MCL (strictest US state) · Michigan EGLEHighest21 ng/L
Perfluorobutanoic acid (PFBA)Detected in 17 systems of 61 testedNo federal or state limit; shown for transparencyHighest14 ng/L
Perfluorodecanoic acid (PFDA)Detected in 1 system of 61 testedNo federal or state limit; shown for transparencyHighest5.6 ng/L
Perfluoroheptanoic acid (PFHpA)Detected in 6 systems of 61 testedNo federal or state limit; shown for transparencyHighest5.3 ng/L
Perfluoropentanoic acid (PFPeA)Detected in 20 systems of 61 testedNo federal or state limit; shown for transparencyHighest27 ng/L
20 PFAS tested, none detected in any systemShow

Tested in these 61 systems: AZUSA LIGHT AND WATER, BELLFLOWER - SOMERSET MWC, BEVERLY HILLS-CITY, WATER DEPT., BURBANK-CITY, WATER DEPT., CAL-AM WATER COMPANY - DUARTE, CAL/AM WATER COMPANY - SAN MARINO, CALIFORNIA WATER SERVICE CO. - DOMINGUEZ, CALIFORNIA WATER SERVICE CO. - ELA, CALIFORNIA WATER SERVICE CO. - HERM/REDO, CALIFORNIA WATER SERVICE CO. - PALOS VER, CERRITOS - CITY, WATER DEPT., CITY OF ALHAMBRA, CITY OF ARCADIA, CITY OF BELL GARDENS, CITY OF INDUSTRY WATERWORKS SYSTEMS, CITY OF SOUTH PASADENA, COMMERCE-CITY, WATER DEPT., COMPTON-CITY, WATER DEPT., COVINA-CITY, WATER DEPT., DOWNEY - CITY, WATER DEPT., EL MONTE-CITY, WATER DEPT., EL SEGUNDO-CITY, WATER DEPT., GLENDALE-CITY, WATER DEPT., GLENDORA-CITY, WATER DEPT., GSWC - ARTESIA, GSWC - BELL, BELL GARDENS, GSWC - FLORENCE/GRAHAM, GSWC - SOUTHWEST, HAWTHORNE-CITY WATER DEPT., HUNTINGTON PARK-CITY, WATER DEPT., INGLEWOOD- CITY, WATER DEPT., LAKEWOOD - CITY, WATER DEPT., LAS VIRGENES MWD, LIBERTY UTILITIES - LYNWOOD, LOMITA-CITY, WATER DEPT., LONG BEACH UTILITIES DEPARTMENT, LOS ANGELES CWWD 29 & 80-MALIBU, LOS ANGELES CWWD 40 REG 4 & 34 LANCASTER, LOS ANGELES-CITY, DEPT. OF WATER & POWER, LYNWOOD-CITY, WATER DEPT., MANHATTAN BEACH-CITY, WATER DEPT., MONROVIA-CITY, WATER DEPT., MONTEREY PARK-CITY, WATER DEPT., NORWALK - CITY, WATER DEPT., PARAMOUNT - CITY, WATER DEPT., PASADENA WATER AND POWER, PICO RIVERA - CITY, WATER DEPT., POMONA - CITY, WATER DEPT., SAN FERNANDO-CITY, WATER DEPT., SAN GABRIEL VALLEY WATER CO.-EL MONTE, SANTA FE SPRINGS - CITY, WATER DEPT., SANTA MONICA-CITY, WATER DIVISION, SIERRA MADRE-CITY, WATER DEPT., SIGNAL HILL - CITY, WATER DEPT., SOUTH GATE-CITY, WATER DEPT., SUBURBAN WATER SYSTEMS-LA MIRADA, SUBURBAN WATER SYSTEMS-SAN JOSE, TORRANCE-CITY, WATER DEPT., TRACT 180 MUTUAL WATER CO., WALNUT PARK MUTUAL WATER CO., WHITTIER-CITY, WATER DEPT.

  • 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)
  • 1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS)
  • 1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS)
  • 1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)
  • 4,8-Dioxa-3H-perfluorononanoic acid (ADONA)
  • 9-Chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS)
  • Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals)
  • N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA)
  • N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA)
  • Nonafluoro-3,6-dioxaheptanoic acid (NFDHA)
  • Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA)
  • Perfluoro-3-methoxypropanoic acid (PFMPA)
  • Perfluoro-4-methoxybutanoic acid (PFMBA)
  • Perfluorododecanoic acid (PFDoA)
  • Perfluoroheptanesulfonic acid (PFHpS)
  • Perfluorononanoic acid (PFNA)
  • Perfluoropentanesulfonic acid (PFPeS)
  • Perfluorotetradecanoic acid (PFTA)
  • Perfluorotridecanoic acid (PFTrDA)
  • Perfluoroundecanoic acid (PFUnA)
61 cities

Cities ranked by the records

Showing 6 of 61 cities · scores are system-level, not tap tests

Ranked by the Purity Score of each city's main water system, highest first. Scores belong to water systems; there is no county score. The score is computed only from contaminants measured in the published EPA record, so this ranks the record, not which city's water is safest. How the score works.

PFAS in Los Angeles County30 of 61 city reports had a PFAS sample above a 2024 EPA limit
  1. Downey44 ng/L
  2. Pico Rivera30 ng/L
  3. South Gate26 ng/L
  4. Norwalk26 ng/L
  5. Cudahy24 ng/L
  6. Lynwood23 ng/L
  7. Huntington Park23 ng/L
  8. Bell Gardens23 ng/L
4.0 ng/L federal MCL · PFOS, ng/LPFAS in California
Lead

0of 61 cities above the 15 µg/L action level

Based on each system's 90th-percentile result. Lead from household plumbing isn't in this record.

Lead in California
Hard water

6cities report hardness · hardest Glendale, 14.3 gpg

5 of 6 are hard on the USGS scale. An aesthetic measure with no federal health limit.

Hard water explained
Who supplies the county

Largest water systems

  1. Los AngelesLOS ANGELES-CITY, DEPT. OF WATER & POWER · CA1910067
    3,875,566 served
  2. Long BeachLONG BEACH UTILITIES DEPARTMENT · CA1910065
    466,772 served
  3. GardenaGSWC - SOUTHWEST · CA1910155
    277,740 served
  4. West Whittier-Los NietosSAN GABRIEL VALLEY WATER CO.-EL MONTE · CA1910039
    240,000 served
  5. LancasterLOS ANGELES CWWD 40 REG 4 & 34 LANCASTER · CA1910070
    208,129 served
  6. GlendaleGLENDALE-CITY, WATER DEPT. · CA1910043
    192,212 served
  7. West CovinaSUBURBAN WATER SYSTEMS-SAN JOSE · CA1910205
    170,523 served
  8. PasadenaPASADENA WATER AND POWER · CA1910124
    165,448 served
  9. PomonaPOMONA - CITY, WATER DEPT. · CA1910126
    151,713 served
  10. CarsonCALIFORNIA WATER SERVICE CO. - DOMINGUEZ · CA1910033
    149,490 served
Questions

Frequently asked

How does Los Angeles County tap water compare across cities?

PurityMap ranks 61 cities in Los Angeles County by the Purity Score of each city's main water system, computed only from contaminants measured in the published EPA record. Scores belong to water systems, not to cities. The highest published score is West Covina's main water system: SUBURBAN WATER SYSTEMS-SAN JOSE · PWSID CA1910205 · Purity Score 100 (Excellent) · Confidence: moderate · Assessed at the water-system level. The ranking compares the records, not which city's water is safest, and your own tap can differ with household plumbing.

How many Los Angeles County cities had a PFAS sample above a 2024 EPA limit?

30 of 61 Los Angeles County city reports had a PFAS sample above a 2024 EPA limit in EPA's UCMR 5 testing, including Downey (PFOS 44 ng/L), Pico Rivera (PFOS 30 ng/L), South Gate (PFOS 26 ng/L). That limit is judged on a yearly average, and water systems have until 2029 to meet it, so a single sample is not a violation. PFAS were detected at any level in 36.

Is there lead in Los Angeles County tap water?

Utilities report lead as a 90th-percentile result from home taps. 18 of 61 Los Angeles County cities reported a value above zero, and none was above the 15 µg/L federal action level. Lead usually comes from a building's own pipes and fixtures, so only a test at your tap tells you what you drink.

Does Los Angeles County have hard water?

Hardness is published in utility water-quality reports for 6 Los Angeles County cities on record; the hardest is Glendale at 14.3 grains per gallon. Hardness affects scale and appliances; it is not a health finding.

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