Monmouth Water Hardness & Quality Report (2026)
Water Hardness
2.1 grains per gallon
Source
reservoir
pH Level
7.3
neutral = 7.0
Lead
0.003 mg/L
✓ Below action level
TDS
66.3 mg/L
Est. Daily Cost
$0.10
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 Monmouth, your appliances are currently losing 5% efficiency due to mineral buildup.
| Appliance | In Monmouth | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 8.4 yrs | 8.5 yrs | -1% |
| Washing Machine | 12.2 yrs | 12 yrs | — |
| Water Heater | 14.1 yrs | 15 yrs | -6% |
Regional Water Comparison
How Monmouth compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Monmouth, Oregon | 36.5 mg/L | 1.5 ppt | 🟢 Soft | reservoir |
| Dallas, Oregon | 92.5 mg/L | 2.6 ppt | 🟡 Moderately Hard | reservoir |
| Salem, Oregon | 82 mg/L | 2.4 ppt | 🟡 Moderately Hard | reservoir |
| Albany, Oregon | 55 mg/L | 1.9 ppt | 🟢 Soft | reservoir |
| Keizer, Oregon | 83 mg/L | 2.4 ppt | 🟡 Moderately Hard | reservoir |
National Benchmark
How Monmouth compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Monmouth | 36.5 mg/L | 🟢 None |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
Bring Badger-quality water to your Monmouth home
Shop water softeners on Amazon.com →
What Makes Monmouth's Water Unique?
Local geology and source profile
Monmouth, Oregon, in Polk County — a Polk County city adjacent to Independence and Dallas in the Oregon Willamette Valley — receives its water from the City of Monmouth Water Department, drawing from the Luckiamute River watershed through the west-central Oregon distribution.
The very soft 36.5 mg/L hardness and very low TDS of 66.3 mg/L reflect the Polk County supply's very soft Oregon Coast Range character — the Eocene Siletz River Volcanics and Miocene Astoria Formation are insoluble-slightly calcareous formations in the Oregon Coast Range; the Luckiamute River watershed at Polk County draws from clean volcanic and marine terrace upland with minimal dissolved mineral content (compare Independence OR: 33/60 in Polk County comparable; Dallas OR: 39/72 in Polk County comparable; Monmouth consistent very soft from the same Polk County Luckiamute River Eocene insoluble supply). The Luckiamute River watershed — Eocene Siletz River Volcanics (insoluble — primary dilutant), Miocene Astoria Formation (slightly calcareous — primary hardness contributor), and Quaternary Willamette Valley alluvium (slightly calcareous — TDS contributor).
At 36.5 mg/L with TDS 66, Monmouth's water is very soft — virtually no scale, but very soft water can be corrosive to metal plumbing. Annual corrosion checks are recommended. The PFAS level of 1.5 ppt is very low — an excellent and clean result for the Oregon Willamette Valley. Review the City of Monmouth's annual water quality report.
Geology & Source: Monmouth in Polk County draws from the Monmouth Water on the Luckiamute River watershed (Polk County, west-central Oregon) — the Oregon Coast Range at Polk County draws from Eocene Siletz River Volcanics (insoluble) and Miocene Astoria Formation (slightly calcareous) — Oregon Polk County Luckiamute River Eocene insoluble supply produces very soft water at 36.5 mg/L with TDS 66.3 mg/L.