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Updated 2026-10-15
County water report

Ventura County Water Quality: 8 Cities Ranked by the Records

Ventura County, California: 8 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 Ventura 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.

LithiumDetected in 7 systems of 8 tested10 µg/L EPA health reference level (screening, not a legal limit) · US EPAHighest140 µg/L
Water hardnessDetected in 1 systemAesthetic, no federal health limit · USGSHighest24.5 gpg
Perfluorohexanesulfonic acid (PFHxS)Detected in 1 system of 8 tested10 ng/L federal MCL (2024) · US EPAHighest3 ng/L
Perfluorobutanesulfonic acid (PFBS)Detected in 1 system of 8 tested2,000 ng/L EPA health advisory (screening, not a legal limit) · US EPAHighest3.1 ng/L
28 substances tested, none detected in any systemShow

Tested in these 8 systems: CAMARILLO WATER DEPT, CITY OF SANTA PAULA, CITY OF THOUSAND OAKS WATER DEPARTMENT, FILLMORE WATER DEPT, OXNARD WATER DEPT, PORT HUENEME CITY WATER DEPT, TRIUNFO WATER & SANITATION DISTRICT, VENTURA WATER DEPARTMENT

  • 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)
  • Lead (90th percentile)
  • 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)
  • Perfluorobutanoic acid (PFBA)
  • Perfluorodecanoic acid (PFDA)
  • Perfluorododecanoic acid (PFDoA)
  • Perfluoroheptanesulfonic acid (PFHpS)
  • Perfluoroheptanoic acid (PFHpA)
  • Perfluorohexanoic acid (PFHxA)
  • Perfluorononanoic acid (PFNA)
  • Perfluorooctanesulfonic acid (PFOS)
  • Perfluorooctanoic acid (PFOA)
  • Perfluoropentanesulfonic acid (PFPeS)
  • Perfluoropentanoic acid (PFPeA)
  • Perfluorotetradecanoic acid (PFTA)
  • Perfluorotridecanoic acid (PFTrDA)
  • Perfluoroundecanoic acid (PFUnA)
8 cities

Cities ranked by the records

Showing 6 of 8 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 Ventura CountyPFAS detected in 1 of 8 cities; none had a sample above a 2024 EPA limit
4.0 ng/L federal MCL · PFOS, ng/LPFAS in California
Lead

0of 8 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

1city reports hardness · Oxnard, 24.5 gpg

Hard on the USGS scale. An aesthetic measure with no federal health limit.

Hard water explained
Who supplies the county

Largest water systems

  1. OxnardOXNARD WATER DEPT · CA5610007
    200,232 served
  2. VenturaVENTURA WATER DEPARTMENT · CA5610017
    112,285 served
  3. Thousand OaksCITY OF THOUSAND OAKS WATER DEPARTMENT · CA5610020
    54,770 served
  4. CamarilloCAMARILLO WATER DEPT · CA5610019
    47,701 served
  5. Santa PaulaCITY OF SANTA PAULA · CA5610011
    31,786 served
  6. Port HuenemePORT HUENEME CITY WATER DEPT · CA5610009
    21,582 served
  7. FillmoreFILLMORE WATER DEPT · CA5610002
    16,419 served
  8. Oak ParkTRIUNFO WATER & SANITATION DISTRICT · CA5610043
    13,898 served
Questions

Frequently asked

How does Ventura County tap water compare across cities?

PurityMap ranks 8 cities in Ventura 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 Oxnard's main water system: OXNARD WATER DEPT · PWSID CA5610007 · 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 Ventura County cities had a PFAS sample above a 2024 EPA limit?

None of the 8 Ventura County city reports had a PFAS sample above a 2024 EPA limit in EPA's UCMR 5 testing. PFAS were detected below the limit in 1.

Is there lead in Ventura County tap water?

Utilities report lead as a 90th-percentile result from home taps. 0 of 8 Ventura 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 Ventura County have hard water?

Hardness is published in utility water-quality reports for 1 Ventura County city on record; the hardest is Oxnard at 24.5 grains per gallon. Hardness affects scale and appliances; it is not a health finding.

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