How does Monmouth's water compare to the national average?

The USA national average is 151 mg/L. Monmouth (≈ 120–179 mg/L) is 1 mg/L softer than average.

Monmouth Water Hardness & Quality Report (2026)

Water Hardness

hard

~120–179 mg/L

Hard

estimated · not lab-verified

Source

mixed

pH Level

7.3

neutral = 7.0

Lead

0.003 mg/L

✓ Below action level

TDS

66.3 mg/L

Est. Daily Cost

$0.40

energy & soap waste

Source: See methodology section below · Updated 2026

hard~120–179 mg/LHard · est.

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 20% efficiency due to mineral buildup.

Appliance	In Monmouth	Soft Water City	Efficiency Loss
Kettle	6.8 yrs	8.5 yrs	-20%
Washing Machine	9.6 yrs	12 yrs	-20%
Water Heater	12 yrs	15 yrs	-20%

Regional Water Comparison

How Monmouth compares to its nearest neighbours

City	Hardness	PFAS (ppt)	Risk	Source
▶ Monmouth, Oregon	≈ 120–179 mg/L	0 ppt	🟠 Hard	mixed
Dallas, Oregon	23 mg/L	0 ppt	🟢 Soft	reservoir
Salem, Oregon	≈ 0–60 mg/L	0 ppt	🟢 Soft	reservoir
Albany, Oregon	≈ 120–179 mg/L	0 ppt	🟠 Hard	reservoir
Keizer, Oregon	≈ 0–60 mg/L	10.8 ppt	🟢 Soft	groundwater

National Benchmark

How Monmouth compares to the USA average

Benchmark	Hardness	Appliance Risk
▶ Monmouth	≈ 120–179 mg/L	🟠 Moderate
USA National Avg	151 mg/L	🟠 Moderate
Scarsdale Top Rated	0.02 mg/L	🟢 None

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What Makes Monmouth's Water Unique?

Local geology and source profile

Source: MixedTDS: 66.3 mg/LpH: 7.3

The City of Monmouth, Oregon draws its water from the Willamette Valley aquifer system, accessing groundwater through wells. This supply is then processed at the city’s treatment facilities before reaching homes and businesses in Monmouth, located in Polk County. The Willamette Valley groundwater basin, replenished by rain and surface water seeping into the ground, forms the origin of Monmouth's water.

The aquifer itself is made up of loose Quaternary alluvial and glacial deposits, featuring layers of sand and gravel that sit atop older Tertiary sedimentary formations. As water percolates through these materials and mineral-rich rock layers, it picks up calcium-bearing minerals, resulting in a supply that is moderately mineralized and moderately hard.

Because the water is moderately hard, you might notice some scale forming on faucets, showerheads, and heating elements over time. Appliances like water heaters, dishwashers, and coffee makers could benefit from occasional descaling to keep them running efficiently. While a water softener isn't strictly necessary for everyone, it could help reduce water spots on dishes and improve how well soap lathers. Monmouth’s annual Consumer Confidence Reports confirm that the city’s water consistently meets all federal and state drinking water standards, with no widespread PFAS contamination issues noted in recent reports.

Geology & Source: Willamette Valley aquifer system; unconsolidated Quaternary alluvial and glacial deposits and Tertiary sedimentary rocks with calcium-bearing minerals create moderate hardness

Other Oregon Water Reports

Dallas

23 mg/L

🟢 Soft

Salem

≈ 0–60 mg/L

🟢 Soft

Albany

≈ 120–179 mg/L

🟠 Hard

Keizer

≈ 0–60 mg/L

🟢 Soft

Report an Issue

Notice an error or missing data? Help us keep this page accurate. If you spot incorrect water hardness, outdated utility info, or missing details, please let us know.

All reports are reviewed by our team. Thank you for supporting data quality!

Frequently Asked Questions

Is Monmouth's water safe to drink?

Yes. Monmouth's water meets all federal safety standards. The hardness is ≈ 120–179 mg/L (Hard), which is safe to drink. High hardness affects appliances and taste, but poses no health risk.

Do I need a water softener in Monmouth?

At ≈ 120–179 mg/L (Hard), Monmouth's water will cause significant limescale on kettles, washing machines, and water heaters. A water softener or descaler is strongly recommended to extend appliance lifespan and reduce energy bills by up to 20%.

How does Monmouth compare to the USA average?

The USA national average is 151 mg/L. Monmouth (≈ 120–179 mg/L) is 1 mg/L below the national average. The softest major city is Scarsdale at just 0.02 mg/L.

Data Sources & Methodology

Water quality data for Monmouth is derived from geographic and geological modelling of the surrounding region. No federal monitoring station data was available for this location.

Estimated

Water Hardness

Modelled estimate based on state-level USGS geological survey data for this region. No direct USGS Water Quality Portal measurement was matched to this city — the value reflects a statistical range calibrated to the state's dominant rock types and typical source water characteristics.

Estimated

Estimated from regional geology and source water characteristics. pH is correlated with water hardness and local bedrock — values may differ from utility-reported figures.

Estimated

TDS — Total Dissolved Solids

Estimated using a derived ratio from water hardness and regional conductance profiles. TDS in natural water correlates strongly with total mineral content including hardness ions.

Measured

PFAS — Perfluoroalkyl and Polyfluoroalkyl Substances

EPA UCMR5 (5th Unregulated Contaminant Monitoring Rule, 2023–2025) — sum of PFAS compounds detected at the public water system serving this city. A value of 0 indicates the system was sampled with no detection above reporting limits.

Modelled

Lead

Modelled estimate based on the EPA Lead and Copper Rule 90th-percentile tap-sample methodology. No publicly available per-city lead dataset with sufficient national coverage exists. Values are a conservative baseline derived from city population tier and infrastructure age — all estimates are maintained below the EPA action level of 0.015 mg/L.

Calculated

Appliance Lifespan

Calculated from water hardness using a linear degradation model. Baseline lifespans represent soft-water performance (kettle: 8.5 yrs, washing machine: 12.0 yrs, water heater: 15.0 yrs). Hard water mineral scale progressively reduces operational life in direct proportion to hardness concentration.