How does Mount Vernon's water compare to the national average?

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

Mount Vernon Water Hardness & Quality Report (2026)

Water Hardness

hard

~120–179 mg/L

Hard

estimated · not lab-verified

Source

reservoir

pH Level

6.5

neutral = 7.0

Lead

0.003 mg/L

✓ Below action level

TDS

183.9 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 Mount Vernon, your appliances are currently losing 20% efficiency due to mineral buildup.

Appliance	In Mount Vernon	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 Mount Vernon compares to its nearest neighbours

City	Hardness	PFAS (ppt)	Risk	Source
▶ Mount Vernon, Virginia	≈ 120–179 mg/L	5.3 ppt	🟠 Hard	reservoir
Woodlawn, Virginia	123.5 mg/L	6.3 ppt	🟠 Hard	reservoir
Hybla Valley, Virginia	≈ 120–179 mg/L	4.7 ppt	🟠 Hard	reservoir
Fort Hunt, Virginia	≈ 120–179 mg/L	7.5 ppt	🟠 Hard	reservoir
Groveton, Virginia	≈ 120–179 mg/L	10.1 ppt	🟠 Hard	reservoir

National Benchmark

How Mount Vernon compares to the USA average

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

Bring Scarsdale-quality water to your Mount Vernon home

Shop water softeners on Amazon.com →

Shop Now

What Makes Mount Vernon's Water Unique?

Local geology and source profile

Source: ReservoirTDS: 183.9 mg/LpH: 6.5

Fairfax Water serves Mount Vernon, Virginia, drawing its supply from the Potomac River and the Occoquan Reservoir. This major regional utility processes water at several treatment facilities before delivering it to homes and businesses across Fairfax County and beyond. The Potomac River watershed originates in the Appalachian region and journeys through the Piedmont physiographic province on its way to Mount Vernon.

The geology beneath Mount Vernon is a mix of Piedmont metamorphic rocks like schist, gneiss, and quartzite, alongside carbonate formations and Coastal Plain sediments. As water travels through these rocks and soils, it picks up dissolved minerals, mainly calcium and magnesium carbonates. This process results in a water supply that is generally considered moderately hard to hard, a common characteristic for this part of Northern Virginia.

With water in this hardness range, you might notice chalky buildup, or scale, on your dishes, faucets, and inside your water heater. You may also find that soaps and detergents don't create as many suds as you're used to. While this doesn't pose a health risk, many residents opt for water softeners to combat these aesthetic issues and help their appliances last longer. Keeping kettles and coffee makers free of scale with regular cleaning is also a good idea. Fairfax Water confirms its water meets all federal safety standards.

Geology & Source: Piedmont metamorphic rocks and Coastal Plain sediments; carbonate formations lead to moderate to hard water

Other Virginia Water Reports

Woodlawn

123.5 mg/L

🟠 Hard

Hybla Valley

≈ 120–179 mg/L

🟠 Hard

Fort Hunt

≈ 120–179 mg/L

🟠 Hard

Groveton

≈ 120–179 mg/L

🟠 Hard

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 Mount Vernon's water safe to drink?

Yes. Mount Vernon'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 Mount Vernon?

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

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