Gaithersburg Water Hardness & Quality Report (2026)
Water Hardness
7.1 grains per gallon
Source
reservoir
pH Level
7.8
neutral = 7.0
Lead
0.004 mg/L
✓ Below action level
TDS
234 mg/L
Est. Daily Cost
$0.32
energy & soap waste
Source: USGS Water Quality Portal · 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 16% efficiency due to mineral buildup.
| Appliance | In Gaithersburg | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 5.6 yrs | 8.5 yrs | -34% |
| Washing Machine | 9.1 yrs | 12 yrs | -24% |
| Water Heater | 10.7 yrs | 15 yrs | -29% |
Regional Water Comparison
How Gaithersburg compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Gaithersburg, Maryland | 121.5 mg/L | 6.5 ppt | 🟠 Hard | reservoir |
| Montgomery Village, Maryland | 81.5 mg/L | 4.3 ppt | 🟡 Moderately Hard | reservoir |
| Redland, Maryland | 142 mg/L | 7.7 ppt | 🟠 Hard | reservoir |
| Germantown, Maryland | 131 mg/L | 7.1 ppt | 🟠 Hard | reservoir |
| Rockville, Maryland | 169.5 mg/L | 9.3 ppt | 🟠 Hard | reservoir |
National Benchmark
How Gaithersburg compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Gaithersburg | 121.5 mg/L | 🟠 Moderate |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Gaithersburg's Water Unique?
Local geology and source profile
Gaithersburg, Maryland, in central Montgomery County — a major Montgomery County city and technology hub (NIST campus) on I-270 northwest of Washington DC — draws its municipal water supply from the Potomac River via the Washington Suburban Sanitary Commission (WSSC Water) Potomac Water Filtration Plant at Potomac, treating Potomac River water for Montgomery and Prince George's Counties including Gaithersburg. Water hardness in Gaithersburg measures 121.5 mg/L — classified as moderately hard.
Gaithersburg's moderate hardness reflects the Potomac River supply characteristics. The Potomac River at the WSSC intake (Great Falls area) drains the Shenandoah Valley carbonates (calcareous Cambrian and Ordovician limestone and dolomite) and the Blue Ridge (Proterozoic Catoctin metabasalt — calcium-poor). The WSSC Potomac Water Filtration Plant treats the Potomac to produce finished water at the treatment plant level that is somewhat softer than the WSSC Patuxent supply. Gaithersburg's moderate 121.5 mg/L is consistent with other inner Montgomery County WSSC Potomac-sourced communities, somewhat softer than Silver Spring (162 mg/L) which may be on a different WSSC transmission loop.
At 121.5 mg/L, Gaithersburg residents encounter moderate scale accumulation. Faucet aerators and showerheads develop deposits after several months — monthly cleaning with citric acid solution is practical maintenance. WSSC Water consistently delivers water meeting all Maryland MDE and EPA Safe Drinking Water Act requirements.
Geology & Source: River supply from the Potomac River via the Washington Suburban Sanitary Commission (WSSC Water) Potomac water filtration plant — the upper Potomac River at Great Falls draining the Blue Ridge Catoctin metabasalt and Appalachian Valley and Ridge calcareous formations; moderately hard supply at 121.5 mg/L in Montgomery County.