Bryn Mawr-Skyway Water Hardness & Quality Report (2026)
Water Hardness
1.7 grains per gallon
Source
reservoir
pH Level
7.2
neutral = 7.0
Lead
0.003 mg/L
✓ Below action level
TDS
52.8 mg/L
Est. Daily Cost
$0.08
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 Bryn Mawr-Skyway, your appliances are currently losing 4% efficiency due to mineral buildup.
| Appliance | In Bryn Mawr-Skyway | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 8.6 yrs | 8.5 yrs | — |
| Washing Machine | 12.5 yrs | 12 yrs | — |
| Water Heater | 14.4 yrs | 15 yrs | -4% |
Regional Water Comparison
How Bryn Mawr-Skyway compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Bryn Mawr-Skyway, Washington | 29.5 mg/L | 1.8 ppt | 🟢 Soft | reservoir |
| Renton, Washington | 27.5 mg/L | 1.7 ppt | 🟢 Soft | reservoir |
| Tukwila, Washington | 46 mg/L | 2.3 ppt | 🟢 Soft | reservoir |
| SeaTac, Washington | 70.5 mg/L | 3.1 ppt | 🟡 Moderately Hard | reservoir |
| Columbia City, Washington | 40 mg/L | 2.1 ppt | 🟢 Soft | reservoir |
National Benchmark
How Bryn Mawr-Skyway compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Bryn Mawr-Skyway | 29.5 mg/L | 🟢 None |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Bryn Mawr-Skyway's Water Unique?
Local geology and source profile
Bryn Mawr-Skyway, Washington, in King County — an unincorporated King County community adjacent to Renton and Tukwila in the south Seattle suburb — receives its water from Seattle Public Utilities (SPU), drawing from the Cedar River (King County, Cedar River Municipal Watershed) through the Seattle metro distribution system.
The very soft 29.5 mg/L hardness and very low TDS of 52.8 mg/L are consistent with the SPU Cedar River-served south Seattle communities (Burien: 27.5 mg/L; SeaTac: ~30 mg/L) — among the softest municipal water supplies in the continental USA. The Cedar River (Cedar River Municipal Watershed, King County) drains the Cascade Range — Eocene Enumclaw Formation (volcanic andesite and basalt — insoluble), Oligocene Index Formation (volcanic — insoluble), and Pleistocene glacial outwash (minimal mineral loading). The entirely insoluble Cascade volcanic watershed produces the very soft Seattle metro supply.
At 29.5 mg/L, Bryn Mawr-Skyway's water is very soft — essentially no scale forms, soap lathers abundantly, and appliances maintain excellent efficiency. Annual descaling is sufficient. The PFAS level of 1.8 ppt is very low — the King County south Seattle suburban corridor and the Cedar River Cascade watershed have no major AFFF military sources adjacent to the protected municipal watershed.
Geology & Source: Bryn Mawr-Skyway in King County draws from Seattle Public Utilities on the Cedar River (King County, northwest Washington) — the Cedar River drains the Cascade Range (Eocene Enumclaw Formation volcanic — insoluble) — Washington King County Cedar River Cascade volcanic watershed produces very soft water at 29.5 mg/L with TDS 52.8 mg/L in this King County Washington community.