Stony Brook Water Hardness & Quality Report (2026)
Water Hardness
5.1 grains per gallon
Source
reservoir
pH Level
7.5
neutral = 7.0
Lead
0.003 mg/L
✓ Below action level
TDS
152.8 mg/L
Est. Daily Cost
$0.23
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 Stony Brook, your appliances are currently losing 12% efficiency due to mineral buildup.
| Appliance | In Stony Brook | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 6.7 yrs | 8.5 yrs | -21% |
| Washing Machine | 10.4 yrs | 12 yrs | -13% |
| Water Heater | 12.1 yrs | 15 yrs | -19% |
Regional Water Comparison
How Stony Brook compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Stony Brook, New York | 87.5 mg/L | 4.3 ppt | 🟡 Moderately Hard | reservoir |
| East Setauket, New York | 177 mg/L | 8.4 ppt | 🟠 Hard | reservoir |
| Setauket-East Setauket, New York | 118 mg/L | 5.7 ppt | 🟡 Moderately Hard | reservoir |
| Saint James, New York | 109.5 mg/L | 5.3 ppt | 🟡 Moderately Hard | reservoir |
| Nesconset, New York | 153.5 mg/L | 7.3 ppt | 🟠 Hard | reservoir |
National Benchmark
How Stony Brook compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Stony Brook | 87.5 mg/L | 🟡 Low |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Stony Brook's Water Unique?
Local geology and source profile
Stony Brook, New York, in Suffolk County — a Suffolk County hamlet adjacent to Setauket and Port Jefferson on north-central Long Island, home to Stony Brook University — receives its water from the Suffolk County Water Authority, drawing from the Long Island Glacial Aquifer (Suffolk County) through the north Long Island distribution.
The moderately soft 87.5 mg/L hardness and TDS of 152.8 mg/L are slightly softer than adjacent Greenlawn (94.5 mg/L) — reflecting the Stony Brook position on the Suffolk County north shore where the Harbor Hills moraine aquifer is slightly less calcareous than the Ronkonkoma moraine deposits farther south. The Long Island Glacial Aquifer at Stony Brook — Pleistocene Harbor Hills glacial outwash (slightly calcareous — primary hardness contributor), Cretaceous Magothy Formation (insoluble — dilutant), and Cretaceous Lloyd Sand (insoluble — deep dilutant).
At 87.5 mg/L, Stony Brook's water is moderately soft — light scale forms slowly in appliances, dishwashers remain efficient, and bathroom fixtures need occasional cleaning. Semi-annual descaling is appropriate. The PFAS level of 4.3 ppt warrants a certified drinking water filter — the Suffolk County north Long Island industrial corridor and Calverton Naval Weapons Station (Suffolk County — former AFFF) contribute to Stony Brook's readings.
Geology & Source: Stony Brook in Suffolk County draws from the Suffolk County Water Authority on the Long Island Glacial Aquifer (Suffolk County, north Long Island, New York) — the aquifer is developed in Pleistocene Harbor Hills glacial outwash (slightly calcareous) and Cretaceous Magothy Formation (insoluble) — New York Suffolk County Long Island Pleistocene glacial aquifer produces moderately soft water at 87.5 mg/L with TDS 152.8 mg/L.