East Renton Highlands Water Hardness & Quality Report (2026)
Water Hardness
2.5 grains per gallon
Source
reservoir
pH Level
7.4
neutral = 7.0
Lead
0.004 mg/L
✓ Below action level
TDS
84.3 mg/L
Est. Daily Cost
$0.11
energy & soap waste
Source: USGS Water Quality Portal · Updated 2026
0–60
mg/L
Soft
61–120
mg/L
Moderately Hard
121–180
mg/L
Hard
180+
mg/L
Very Hard
Appliance Damage Report
In East Renton Highlands, your appliances are currently losing 6% efficiency due to mineral buildup.
| Appliance | In East Renton Highlands | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 8.2 yrs | 8.5 yrs | -4% |
| Washing Machine | 12 yrs | 12 yrs | — |
| Water Heater | 13.9 yrs | 15 yrs | -7% |
Regional Water Comparison
How East Renton Highlands compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ East Renton Highlands, Washington | 42 mg/L | 2.2 ppt | 🟢 Soft | reservoir |
| Fairwood, Washington | 64.5 mg/L | 2.9 ppt | 🟡 Moderately Hard | reservoir |
| Newcastle, Washington | 71.5 mg/L | 3.1 ppt | 🟡 Moderately Hard | reservoir |
| Issaquah, Washington | 44 mg/L | 2.2 ppt | 🟢 Soft | reservoir |
| West Lake Sammamish, Washington | 17.5 mg/L | 1.4 ppt | 🟢 Soft | reservoir |
National Benchmark
How East Renton Highlands compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ East Renton Highlands | 42 mg/L | 🟢 None |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes East Renton Highlands's Water Unique?
Local geology and source profile
East Renton Highlands, Washington, in King County — a King County unincorporated community adjacent to Renton and Maple Valley in the southeast Seattle suburbs — receives its water from Seattle Public Utilities or Coal Creek Utility District, drawing from Chester Morse Lake on the Cedar River through the west-central Washington distribution.
The very soft 42 mg/L hardness and low TDS of 84.3 mg/L reflect the King County Cedar River supply's very soft Cascade volcanic character — the Miocene Columbia River Basalt and Quaternary Cascade andesite are highly insoluble volcanic formations contributing negligible dissolved minerals to the pristine Cedar River watershed (compare Renton WA: 40/80 in King County comparable; Maple Valley WA: 43/88 in King County comparable; East Renton Highlands consistent very soft from the same King County Cedar River Miocene basaltic supply). The Cedar River watershed — Miocene Columbia River Basalt (insoluble — primary dilutant), Quaternary Cascade andesite (insoluble — secondary dilutant), and Quaternary Cedar River alluvium (slightly calcareous — minimal TDS).
At 42 mg/L with TDS 84, East Renton Highlands' water is very soft — virtually no scale buildup. Soft water can be corrosive — check for blue-green copper staining in older plumbing. The PFAS level of 2.2 ppt is very low — an excellent result for the Seattle suburbs. Review Seattle Public Utilities' annual water quality report.
Geology & Source: East Renton Highlands in King County draws from the Seattle Water on Chester Morse Lake (King County, west-central Washington) — the Cedar River watershed at King County drains Miocene Columbia River Basalt (insoluble) and Quaternary Cascade andesite (insoluble) — Washington King County Cedar River Miocene basaltic supply produces very soft water at 42 mg/L with TDS 84.3 mg/L.