Lake Forest Park Water Hardness & Quality Report (2026)
Water Hardness
1.3 grains per gallon
Source
reservoir
pH Level
7.2
neutral = 7.0
Lead
0.002 mg/L
✓ Below action level
TDS
35.6 mg/L
Est. Daily Cost
$0.06
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 Lake Forest Park, your appliances are currently losing 3% efficiency due to mineral buildup.
| Appliance | In Lake Forest Park | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 8.9 yrs | 8.5 yrs | — |
| Washing Machine | 12.8 yrs | 12 yrs | — |
| Water Heater | 14.7 yrs | 15 yrs | -2% |
Regional Water Comparison
How Lake Forest Park compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Lake Forest Park, Washington | 21.5 mg/L | 1.5 ppt | 🟢 Soft | reservoir |
| Kenmore, Washington | 73.5 mg/L | 3.2 ppt | 🟡 Moderately Hard | reservoir |
| Mountlake Terrace, Washington | 58.5 mg/L | 2.7 ppt | 🟢 Soft | reservoir |
| Shoreline, Washington | 15 mg/L | 1.3 ppt | 🟢 Soft | reservoir |
| Inglewood-Finn Hill, Washington | 43 mg/L | 2.2 ppt | 🟢 Soft | reservoir |
National Benchmark
How Lake Forest Park compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Lake Forest Park | 21.5 mg/L | 🟢 None |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Lake Forest Park's Water Unique?
Local geology and source profile
Lake Forest Park, Washington, in King County — a King County city adjacent to Seattle and Kenmore on Lake Washington in northwest Washington — receives its water from Seattle Public Utilities, drawing from the Cedar River or Tolt River reservoir (King County) through the north Seattle metro distribution.
The very soft 21.5 mg/L hardness and very low TDS of 35.6 mg/L place Lake Forest Park among the softest water cities in this dataset — reflecting the Cascade Range watershed's insoluble Oligocene and Miocene volcanic and plutonic formations producing near-pure snowmelt runoff with minimal dissolved minerals, consistent with the Seattle metro SPU system (compare Port Orchard WA: 42 mg/L on the same Cascade soft supply). The Cedar-Tolt watershed at King County — Oligocene Stevens Ridge Formation (insoluble — primary dilutant), Quaternary Cascade volcanic basalt (insoluble — secondary dilutant), and minor Pleistocene glacial till (slightly calcareous — trace hardness contributor).
At 21.5 mg/L, Lake Forest Park's water is very soft — no scale buildup, appliances last their full service life, and no softening is needed. Water is ideal for all uses. The PFAS level of 1.5 ppt is very low — no urgent filtration needed, routine monitoring is sufficient.
Geology & Source: Lake Forest Park in King County draws from the Seattle Public Utilities on Cedar River or Tolt River reservoirs (King County, northwest Washington) — the Cedar-Tolt watershed drains the Cascade Range (Oligocene Stevens Ridge Formation — insoluble) and Quaternary volcanic basalt (insoluble) — Washington King County Cedar-Tolt Cascade reservoir insoluble volcanic supply produces very soft water at 21.5 mg/L with TDS 35.6 mg/L.