Water Quality in Kennewick, WA: 39 Violations — Grade C
Grade C · Score 58/100 · 5 water systems · Updated 2026-05-03
Kennewick's water has moderate compliance issues. Residents in affected areas should consider filtration.
Data: EPA Safe Drinking Water Information System (SDWIS) Last verified: 2026-05-03
SDWIS records for Kennewick, WA show 39 EPA violations documented for the local water supply — these span the full range of reportable events from health-based exceedances to monitoring and reporting lapses registered with the federal program.
Water Quality by ZIP Code in Kennewick
Water quality varies across Kennewick's 3 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | Grade | Score | Violations | Health | |
|---|---|---|---|---|---|
| 99336 | C | 58 | 13 | 7 | View report → |
| 99337 | C | 58 | 13 | 7 | View report → |
| 99338 | C | 58 | 13 | 7 | View report → |
Violation Trend
EPA violations recorded for water systems serving Kennewick.
Water Quality Overview
Kennewick, Washington receives a water quality grade of C with an overall score of 58 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).
The 5 water systems serving Kennewick have accumulated 39 EPA violations, including 21 health-based violations. These violations are tracked across 3 ZIP codes serving approximately 121,130 people.
What Grade C Means
A grade of C indicates moderate compliance issues. Kennewick's water systems have some violations that warrant attention. While the water may still be safe for most people, residents in affected ZIP codes should consider additional testing or filtration.
Lead Levels
The average 90th percentile lead level across Kennewick water systems is 0.0019 mg/L — within EPA limits. No ZIP codes exceed the EPA lead action level.
With 47% of homes built before 1986, Kennewick has a higher-than-average risk of lead from older plumbing. Lead solder was banned in 1986, and homes built before this date may have lead in pipes, solder joints, or fixtures.
Radon Risk
Kennewick is in EPA Radon Zone 2 (Moderate risk). Testing is recommended, especially for homes with basements or ground-level living spaces.
Water Systems Serving Kennewick
Kennewick is served by 5 community water systems regulated under the Safe Drinking Water Act. These systems collectively serve approximately 121,130 people across 3 ZIP codes.
Each water system is identified by a Public Water System ID (PWSID) and is required to:
- Test for over 90 regulated contaminants on a regular schedule
- Report results to the EPA and state regulators
- Issue an annual Consumer Confidence Report (CCR) to all customers
- Take corrective action when violations occur
The EPA has taken 21 enforcement actions against water systems serving Kennewick. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Kennewick
Enter your ZIP code on ZipCheckup to see your specific water system data, including contaminant levels, violation history, and safety scores
Request your CCR — your water utility must provide an annual Consumer Confidence Report with detailed test results for all monitored contaminants
Get a home test — certified kits cost $20–$50 and test for lead, bacteria, and common contaminants. Professional lab tests ($150–$400) cover a broader panel
Consider filtration — NSF-certified filters can remove specific contaminants. Reverse osmosis removes the broadest range; activated carbon is effective for chlorine and many organics
Check for advisories — monitor your local utility website and local news for boil water advisories or system alerts
Contaminants Detected in Kennewick Water Systems
The following contaminants have been detected or caused violations across Kennewick's water systems:
| Contaminant | Category | MCL | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|---|
| Haloacetic Acids (HAA5) | Disinfection Byproducts | 0.06 mg/L | 18 | 3 | Yes |
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 0.08 mg/L | 12 | 3 | Yes |
| Lead | Inorganic | 0.015 mg/L | 3 | 3 | No |
MCL = Maximum Contaminant Level (EPA enforceable standard). Health-based violations indicate levels that may pose direct health risks.
Violation Trend Over Time
Year-by-year EPA violations recorded for water systems serving Kennewick:
| Year | Total Violations | Health-Based |
|---|---|---|
| 2022 | 6 | 6 |
| 2023 | 12 | 12 |
| 2024 | 3 | 3 |
Violations have decreased from 6 in 2022 to 3 in 2024, indicating improving compliance.
EPA Enforcement History
The EPA and state regulators have taken 7 enforcement actions against water systems serving Kennewick. Recent actions:
| Date | Action Type |
|---|---|
| 2025-09-19 | State Order Extension |
| 2024-10-03 | State Filed Suit |
| 2024-09-17 | State Order Extension |
| 2023-10-03 | State Order Extension |
| 2023-08-08 | State Order Extension |
| 2023-03-22 | State Order Extension |
| 2022-09-27 | State Order Extension |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2025-09-19.
Kennewick vs. Nearby Washington Cities
How Kennewick's water quality compares to similar cities in Washington:
| City | Grade | Violations | Systems | Population |
|---|---|---|---|---|
| Kennewick | C | 39 | 5 | 121,130 |
| Olympia | A | 22 | 5 | 120,251 |
| Lacey | A | 0 | 5 | 119,607 |
| Pasco | B | 26 | 5 | 118,601 |
Recommended Water Filters for Kennewick
Based on contaminants detected in Kennewick's water supply, these filter types are recommended:
Granular Activated Carbon (GAC, whole-house POE)
- Removes: Trihalomethane (TTHM)
- Effectiveness: 80-99%
- Cost range: $400–$2000
- Certification: NSF/ANSI 53
- Recommended products:
Water Quality by ZIP Code in Kennewick
Water quality varies across Kennewick's ZIP codes. The table below shows the worst-scoring and best-scoring areas:
Common Questions About Kennewick Water
These are the most common questions residents search for about water quality in Kennewick, Washington:
Is Kennewick water hard or soft? Water hardness varies by source. Kennewick's 5 water systems use multiple sources. Check your ZIP code report for specific hardness data.
Can I drink Kennewick tap water? Kennewick's water receives a grade of C (58/100). There are 21 health-based violations — consider filtration.
What is the best water filter for Kennewick? Based on detected contaminants, a granular activated carbon (gac, whole-house poe) filter is most recommended. See our Water Filter Matcher for personalized recommendations.
Kennewick vs. Washington Average
Understanding how Kennewick compares to the broader Washington average helps contextualize your local water quality. Factors like water source, treatment methods, and infrastructure age all contribute to differences between cities in the same state.
To see how individual neighborhoods compare, check the ZIP code reports below — water quality can vary significantly even within Kennewick.
ZIP Codes in Kennewick
Kennewick spans 3 ZIP codes. The ZIP with the lowest water quality score is 99336. Each ZIP code has its own water quality profile based on the specific water system serving that area. Check each ZIP code for detailed contaminant data, violation history, and system information.
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Lead/copper: EPA Lead and Copper Rule sampling data
- Radon: EPA Map of Radon Zones
- Enforcement: EPA ECHO database
- Filter recommendations: NSF/ANSI certified products
Updated daily.