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Updated 2026-10-15
County water report

Benton County Water Quality: 4 Cities Ranked by the Records

Benton County, Washington: 4 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 Benton 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 2 systems of 4 tested4.0 ng/L federal MCL (2024) · US EPAHighest17 ng/L
LithiumDetected in 3 systems of 4 tested10 µg/L EPA health reference level (screening, not a legal limit) · US EPAHighest31.9 µg/L
Perfluorooctanoic acid (PFOA)Detected in 2 systems of 4 tested4.0 ng/L federal MCL (2024) · US EPAHighest10.1 ng/L
Perfluorohexanesulfonic acid (PFHxS)Detected in 2 systems of 4 tested10 ng/L federal MCL (2024) · US EPAHighest10.6 ng/L
Lead (90th percentile)Detected in 2 systems of 4 tested15 µg/L federal action level · US EPAHighest2.4 µg/L
Perfluorobutanesulfonic acid (PFBS)Detected in 2 systems of 4 tested2,000 ng/L EPA health advisory (screening, not a legal limit) · US EPAHighest8.9 ng/L
Perfluorohexanoic acid (PFHxA)Detected in 2 systems of 4 tested400,000 ng/L Michigan EGLE state MCL (strictest US state) · Michigan EGLEHighest11.6 ng/L
Perfluorobutanoic acid (PFBA)Detected in 1 system of 4 testedNo federal or state limit; shown for transparencyHighest6.6 ng/L
  • RICHLAND CITY OF6.6 ng/LSample date: 2023-03-13 to 2023-12-04
  • KENNEWICK CITY OFNot detected · below 5.0 ng/L lab reporting limitSample date: 2023-02-06 to 2024-01-03
  • SUNNYSIDE CITY OFNot detected · below 5.0 ng/L lab reporting limitSample date: 2025-08-27
  • WEST RICHLAND CITY OFNot detected · below 5.0 ng/L lab reporting limitSample date: 2024-02-28 to 2024-10-01
2 more contaminants detectedShow
Perfluoroheptanoic acid (PFHpA)Detected in 1 system of 4 testedNo federal or state limit; shown for transparencyHighest5.8 ng/L
  • RICHLAND CITY OF5.8 ng/LSample date: 2023-03-13 to 2023-12-04
  • KENNEWICK CITY OFNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-02-06 to 2024-01-03
  • SUNNYSIDE CITY OFNot detected · below 3.0 ng/L lab reporting limitSample date: 2025-08-27
  • WEST RICHLAND CITY OFNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-02-28 to 2024-10-01
Perfluoropentanoic acid (PFPeA)Detected in 2 systems of 4 testedNo federal or state limit; shown for transparencyHighest14.5 ng/L
21 PFAS tested, none detected in any systemShow

Tested in these 4 systems: KENNEWICK CITY OF, RICHLAND CITY OF, SUNNYSIDE CITY OF, WEST RICHLAND CITY OF

  • 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)
  • Perfluorodecanoic acid (PFDA)
  • Perfluorododecanoic acid (PFDoA)
  • Perfluoroheptanesulfonic acid (PFHpS)
  • Perfluorononanoic acid (PFNA)
  • Perfluoropentanesulfonic acid (PFPeS)
  • Perfluorotetradecanoic acid (PFTA)
  • Perfluorotridecanoic acid (PFTrDA)
  • Perfluoroundecanoic acid (PFUnA)
4 cities

Cities ranked by the records

Showing 4 of 4 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 Benton County2 of 4 city reports had a PFAS sample above a 2024 EPA limit
  1. Richland17 ng/L
  2. Kennewick11.5 ng/L
4.0 ng/L federal MCL · PFOS, ng/LPFAS in Washington
Lead

0of 4 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 Washington
Who supplies the county

Largest water systems

  1. KennewickKENNEWICK CITY OF · WA5338100
    118,164 served
  2. RichlandRICHLAND CITY OF · WA5372250
    106,499 served
  3. West RichlandWEST RICHLAND CITY OF · WA5394900
    21,231 served
  4. SunnysideSUNNYSIDE CITY OF · WA5385400
    17,194 served
Questions

Frequently asked

How does Benton County tap water compare across cities?

PurityMap ranks 4 cities in Benton 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 Richland's main water system: WEST RICHLAND CITY OF · PWSID WA5394900 · 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 Benton County cities had a PFAS sample above a 2024 EPA limit?

2 of 4 Benton County city reports had a PFAS sample above a 2024 EPA limit in EPA's UCMR 5 testing, including Richland (PFOS 17 ng/L), Kennewick (PFOS 11.5 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 2.

Is there lead in Benton County tap water?

Utilities report lead as a 90th-percentile result from home taps. 2 of 4 Benton 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.

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