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

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

Merrifield Water Hardness & Quality Report (2026)

Water Hardness

hard

~120–179 mg/L

Hard

estimated · not lab-verified

Source

reservoir

pH Level

8.3

neutral = 7.0

Lead

0.008 mg/L

✓ Below action level

TDS

498 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 Merrifield, your appliances are currently losing 20% efficiency due to mineral buildup.

Appliance	In Merrifield	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 Merrifield compares to its nearest neighbours

City	Hardness	PFAS (ppt)	Risk	Source
▶ Merrifield, Virginia	≈ 120–179 mg/L	9.9 ppt	🟠 Hard	reservoir
Idylwood, Virginia	≈ 120–179 mg/L	4.8 ppt	🟠 Hard	reservoir
West Falls Church, Virginia	≈ 0–60 mg/L	6.5 ppt	🟢 Soft	reservoir
Tysons, Virginia	≈ 120–179 mg/L	9.3 ppt	🟠 Hard	reservoir
Vienna, Virginia	≈ 120–179 mg/L	18 ppt	🟠 Hard	reservoir

National Benchmark

How Merrifield compares to the USA average

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

Local geology and source profile

Source: ReservoirTDS: 498 mg/LpH: 8.3

Fairfax Water supplies Merrifield, Virginia, drawing from two main sources: the Potomac River and the Occoquan Reservoir. Water from the Potomac River is treated at the Corbalis Treatment Plant, while water from the Occoquan Reservoir is processed at the Griffith Treatment Plant. These facilities use standard methods like coagulation, sedimentation, filtration, and disinfection. The Potomac River watershed is vast, covering 14,670 square miles, while the Occoquan Reservoir watershed encompasses 594 square miles of forested land in the Piedmont.

The geology beneath these water sources contributes to the water's character. The Potomac River flows over ancient metamorphic and igneous rocks, including those from the Potomac Group, which dissolve minerals like calcium and magnesium. The Occoquan Reservoir is situated over granitic and schistose bedrock from the Catoctin Formation. Weathered soils from these Piedmont formations release bicarbonates and other minerals, resulting in water that is naturally moderately hard.

This moderately hard water can lead to scale buildup in appliances like water heaters, dishwashers, and coffee makers, reducing their efficiency over time. You might also notice reduced soap lathering, requiring more detergent and potentially leading to spotted dishes. Regular descaling with vinegar can help manage mineral deposits, and wiping fixtures regularly prevents unsightly rings. For persistent issues with scale or residue, installing a water softener is often a good solution for homeowners in the area.

Geology & Source: Potomac River watershed and Occoquan Reservoir; metamorphic and igneous rocks like gneisses, schists, and granites; moderate hardness

Other Virginia Water Reports

Idylwood

≈ 120–179 mg/L

🟠 Hard

West Falls Church

≈ 0–60 mg/L

🟢 Soft

Tysons

≈ 120–179 mg/L

🟠 Hard

Vienna

≈ 120–179 mg/L

🟠 Hard

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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 Merrifield's water safe to drink?

Yes. Merrifield'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 Merrifield?

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

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