How does Oak Harbor's water compare to the national average?

The USA national average is 151 mg/L. Oak Harbor (23 mg/L) is 128 mg/L softer than average.

Oak Harbor Water Hardness & Quality Report (2026)

Water Hardness

23mg/L

Soft

1.3 grains per gallon

Source

reservoir

pH Level

7.2

neutral = 7.0

Lead

0.002 mg/L

✓ Below action level

TDS

38.7 mg/L

Est. Daily Cost

$0.06

energy & soap waste

Source: See methodology section below · Updated 2026

23mg/L as CaCO₃Soft

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 Oak Harbor, your appliances are currently losing 3% efficiency due to mineral buildup.

Appliance	In Oak Harbor	Soft Water City	Efficiency Loss
Kettle	8.2 yrs	8.5 yrs	-4%
Washing Machine	11.6 yrs	12 yrs	-3%
Water Heater	14.6 yrs	15 yrs	-3%

Regional Water Comparison

How Oak Harbor compares to its nearest neighbours

City	Hardness	PFAS (ppt)	Risk	Source
▶ Oak Harbor, Washington	23 mg/L	0 ppt	🟢 Soft	reservoir
Camano, Washington	≈ 120–179 mg/L	2.8 ppt	🟠 Hard	groundwater
Anacortes, Washington	≈ 0–60 mg/L	2.3 ppt	🟢 Soft	reservoir
Mount Vernon, Washington	≈ 0–60 mg/L	21.1 ppt	🟢 Soft	reservoir
Sedro-Woolley, Washington	≈ 0–60 mg/L	3.2 ppt	🟢 Soft	groundwater

National Benchmark

How Oak Harbor compares to the USA average

Benchmark	Hardness	Appliance Risk
▶ Oak Harbor	23 mg/L	🟢 None
USA National Avg	151 mg/L	🟠 Moderate
Scarsdale Top Rated	0.02 mg/L	🟢 None

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What Makes Oak Harbor's Water Unique?

Local geology and source profile

Source: ReservoirTDS: 38.7 mg/LpH: 7.2

Oak Harbor is served by the City of Oak Harbor Water Utility, which supplies over 22,000 residents across the community from Coupeville to Naval Air Station Whidbey Island in Island County, Washington. The utility sources water from local groundwater aquifers beneath Whidbey Island and also purchases surface water. Treatment includes sodium hypochlorite disinfection; the utility reports no additional treatment methods in recent filings. The 2024 Water Quality Report (Consumer Confidence Report) is available through the City of Oak Harbor website, with after-hours water quality concerns directed to 360-679-9567.

The geology of Whidbey Island reflects the Puget Sound lowlands, shaped by Quaternary glaciation. The island's aquifer systems are composed of glacial and post-glacial deposits overlying older sedimentary bedrock. These hydrogeological conditions create a water supply with moderate mineral content typical of the region, influenced by both glacial history and proximity to marine environments. The groundwater component draws from aquifers that have accumulated dissolved minerals through contact with glacial till and underlying sedimentary formations.

Oak Harbor's water hardness is not publicly confirmed in available Consumer Confidence Reports; specific softener recommendations cannot be definitively stated without verified measurements. Residents experiencing scale buildup on fixtures or reduced soap effectiveness should contact the utility at 360-279-4530 (Monday–Friday, 8:00 AM–4:30 PM). Water quality testing has identified contaminants including arsenic, chromium-6, chloroform, and trihalomethanes (TTHMs) at levels meeting EPA legal limits; the current Consumer Confidence Report provides full compliance details.

Geology & Source: Whidbey Island — Quaternary glacial deposits over sedimentary bedrock; Puget Sound lowland glacial aquifers yield moderately mineralized water; marine and glacial influence; blended groundwater and purchased surface water supply

Other Washington Water Reports

Camano

≈ 120–179 mg/L

🟠 Hard

Anacortes

≈ 0–60 mg/L

🟢 Soft

Mount Vernon

≈ 0–60 mg/L

🟢 Soft

Sedro-Woolley

≈ 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 Oak Harbor's water safe to drink?

Yes. Oak Harbor's water meets all federal safety standards. The hardness is 23 mg/L (Soft), which is safe to drink. High hardness affects appliances and taste, but poses no health risk.

Do I need a water softener in Oak Harbor?

Oak Harbor's water is soft at 23 mg/L. A water softener is generally not necessary, though a carbon filter can improve taste and remove any remaining chlorine.

How does Oak Harbor compare to the USA average?

The USA national average is 151 mg/L. Oak Harbor (23 mg/L) is 128 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 Oak Harbor 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.