WaterQ

Kennewick, WA vs Seattle, WA

Which City Has Better Water Quality?

Kennewick, WA and Seattle, WA currently share an identical average WaterQ score, each scoring 82 out of 100. Both cities currently carry a B grade overall. Because a WaterQ score is an aggregate across all public water systems serving a city, near-identical scores can still mask differences at the system level, so residents of either city should review their specific water system's record for the most relevant detail.

Seattle, WA is the larger of the two, with 1.1 million more residents than Kennewick. Seattle is served by 6 public water systems, compared with 5 in Kennewick — a difference of 1 system. A larger number of systems often reflects a more fragmented distribution network spanning multiple utilities, suburbs, or rural service areas, while a single large utility serving a big population can benefit from economies of scale in treatment and monitoring, but may also face more complex, aging infrastructure to maintain.

For residents of either Kennewick or Seattle, the most useful next step is to look up the specific water system that serves your address, since city-wide averages combine results from every system in the area. Visit the Kennewick or Seattle city pages below for a breakdown of local systems, recent violations, and contaminant-specific data, or browse WaterQ's contaminants directory to learn what each measured substance means for health.

Detailed Comparison

Metric Kennewick Seattle
Water Quality Score 82 82
Grade B B
Water Systems 5 6
Population 121,130 1,211,343
County
State WA WA

Analysis

Similar Scores
Marginal difference
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Population Difference
Seattle has 1.1M more people
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More Water Systems
Seattle has 1 more system(s)
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Frequently asked questions

Which city has better tap water quality: Kennewick or Seattle?

Kennewick and Seattle currently have similar overall WaterQ scores. Review each city page for recent test and violation details.

How are Kennewick and Seattle water scores calculated?

WaterQ scores are based on EPA-reported drinking water data, including contaminant detections, violations, and compliance records across local systems.

Where can I view full reports for Kennewick and Seattle?

Use the city detail pages to see water systems, score breakdowns, and trend context for Kennewick, WA and Seattle, WA.