Gaithersburg Water Hardness & Quality Report (2026)
Water Hardness
~120–179 mg/L
Hardestimated · not lab-verified
Source
reservoir
pH Level
7.8
neutral = 7.0
Lead
0.004 mg/L
✓ Below action level
TDS
234 mg/L
Est. Daily Cost
$0.40
energy & soap waste
Source: See methodology section below · Updated 2026
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 Gaithersburg, your appliances are currently losing 20% efficiency due to mineral buildup.
| Appliance | In Gaithersburg | 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 Gaithersburg compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Gaithersburg, Maryland | ≈ 120–179 mg/L | 6.5 ppt | 🟠 Hard | reservoir |
| Montgomery Village, Maryland | ≈ 0–60 mg/L | 4.3 ppt | 🟢 Soft | reservoir |
| Redland, Maryland | ≈ 120–179 mg/L | 7.7 ppt | 🟠 Hard | reservoir |
| Germantown, Maryland | ≈ 120–179 mg/L | 7.1 ppt | 🟠 Hard | reservoir |
| Rockville, Maryland | ≈ 120–179 mg/L | 9.3 ppt | 🟠 Hard | reservoir |
National Benchmark
How Gaithersburg compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Gaithersburg | ≈ 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 Gaithersburg's Water Unique?
Local geology and source profile
WSSC Water (Washington Suburban Sanitary Commission) supplies Gaithersburg in Montgomery County, Maryland. The primary source is the Potomac River, drawn from intakes upstream of Washington, DC. Water is treated at the Washington Aqueduct facilities operated by the U.S. Army Corps of Engineers, with distribution through WSSC infrastructure serving over 1.8 million customers in Montgomery and Prince George's Counties.
The Potomac River watershed spans 14,670 square miles across four states and DC, with headwaters in the Appalachian Mountains. Geology features resistant quartzites and schists in the upstream basin, while carbonate rocks including the Devonian Keyser and Helderberg limestones in tributaries elevate mineral content. Surface water chemistry reflects dissolution of these Paleozoic carbonates and weathering of mafic minerals, yielding a moderately mineralised supply with seasonal variation in mineral loading from fluctuating river flows.
Moderately hard water in Gaithersburg promotes scale buildup on fixtures, kettles, and heating elements, reducing efficiency over time. Dishwashers, water heaters, and laundry machines experience reduced lifespan and higher energy use. Regular vinegar descaling, scale inhibitors, and low-flow aerators help; a water softener is recommended for optimal appliance performance and soap efficiency. WSSC Water maintains EPA compliance per annual Consumer Confidence Reports, using coagulation, sedimentation, filtration, and chloramination; typical pH 7.4–7.8. Lead/copper rule is met through corrosion control; no notable PFAS exceedances reported; occasional manganese or disinfection byproducts are monitored.
Geology & Source: Potomac River watershed — Appalachian Piedmont Precambrian-Paleozoic metamorphic rocks; Devonian Keyser and Helderberg limestone tributaries dissolve calcium and magnesium — moderately mineralised supply; seasonal river flows affect mineral loading
Other Maryland Water Reports
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Frequently Asked Questions
Is Gaithersburg's water safe to drink?
Do I need a water softener in Gaithersburg?
How does Gaithersburg compare to the USA average?
Data Sources & Methodology
Water quality data for Gaithersburg is derived from geographic and geological modelling of the surrounding region. No federal monitoring station data was available for this location.
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.
pH
Estimated from regional geology and source water characteristics. pH is correlated with water hardness and local bedrock — values may differ from utility-reported figures.
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.
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.
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.
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.