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

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

Cornelius Water Hardness & Quality Report (2026)

Water Hardness

hard

~120–179 mg/L

Hard

estimated · not lab-verified

Source

reservoir

pH Level

7.3

neutral = 7.0

Lead

0.003 mg/L

✓ Below action level

TDS

66 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 Cornelius, your appliances are currently losing 20% efficiency due to mineral buildup.

Appliance	In Cornelius	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 Cornelius compares to its nearest neighbours

City	Hardness	PFAS (ppt)	Risk	Source
▶ Cornelius, Oregon	≈ 120–179 mg/L	0 ppt	🟠 Hard	reservoir
Forest Grove, Oregon	≈ 0–60 mg/L	0 ppt	🟢 Soft	reservoir
Hillsboro, Oregon	≈ 120–179 mg/L	0 ppt	🟠 Hard	reservoir
Aloha, Oregon	≈ 120–179 mg/L	2.1 ppt	🟠 Hard	groundwater
Bethany, Oregon	≈ 0–60 mg/L	2.2 ppt	🟢 Soft	reservoir

National Benchmark

How Cornelius compares to the USA average

Benchmark	Hardness	Appliance Risk
▶ Cornelius	≈ 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 Cornelius's Water Unique?

Local geology and source profile

Source: ReservoirTDS: 66 mg/LpH: 7.3

Cornelius water comes to about 12,000 residents in Washington County, Oregon, from surface water purchased via the Tualatin Valley Water District. The primary sources are the Tualatin River and Henry Hagg Lake reservoir, with water treated at the city's conventional filtration plant on N Barlow St. This facility uses coagulation, sedimentation, filtration, and chlorination to ensure safe drinking water. The utility also monitors the Tualatin River Watershed, which includes the Chehalem Mountains and Coast Range foothills, drawing from Henry Hagg Lake (also known as Scoggins Reservoir) on Scoggins Creek.

The region's geology features Quaternary alluvial deposits resting on Tertiary sedimentary rocks like the Willamette Formation siltstones and sandstones. Beneath these lie the Eocene Siletz River Volcanics. Runoff interacts with alkaline earth metals leaching from the Columbia River Basalt Group flows and sedimentary rock. This geological mix, interacting with volcanic terrains and carbonate-rich soils, results in a moderately mineralized supply characteristic of Pacific Northwest river systems.

Homeowners might notice subtle scale buildup in kettles or reduced lathering from soap with this moderately hard water. Spotting on glassware after dishwashing is also common. Appliances like hot water heaters, washing machines, and dishwashers can gradually lose efficiency due to mineral deposits. Regularly descaling faucets and appliances with vinegar can help. For those who prefer spot-free results or notice significant soap inefficiency, installing a water softener is advisable.

Geology & Source: Tualatin River watershed; Quaternary alluvial deposits and Tertiary Willamette Formation siltstones/sandstones over Siletz River Volcanics impart moderate hardness

Other Oregon Water Reports

Forest Grove

≈ 0–60 mg/L

🟢 Soft

Hillsboro

≈ 120–179 mg/L

🟠 Hard

Aloha

≈ 120–179 mg/L

🟠 Hard

Bethany

≈ 0–60 mg/L

🟢 Soft

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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 Cornelius's water safe to drink?

Yes. Cornelius'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 Cornelius?

At ≈ 120–179 mg/L (Hard), Cornelius'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 Cornelius compare to the USA average?

The USA national average is 151 mg/L. Cornelius (≈ 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 Cornelius 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.