Selden Water Hardness & Quality Report (2026)
Water Hardness
6 grains per gallon
Source
reservoir
pH Level
7.6
neutral = 7.0
Lead
0.004 mg/L
✓ Below action level
TDS
193 mg/L
Est. Daily Cost
$0.27
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 Selden, your appliances are currently losing 14% efficiency due to mineral buildup.
| Appliance | In Selden | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 6.2 yrs | 8.5 yrs | -27% |
| Washing Machine | 9.8 yrs | 12 yrs | -18% |
| Water Heater | 11.5 yrs | 15 yrs | -23% |
Regional Water Comparison
How Selden compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Selden, New York | 102 mg/L | 4.9 ppt | 🟡 Moderately Hard | reservoir |
| Coram, New York | 71.5 mg/L | 3.5 ppt | 🟡 Moderately Hard | reservoir |
| Farmingville, New York | 101 mg/L | 4.9 ppt | 🟡 Moderately Hard | reservoir |
| Holtsville, New York | 174.5 mg/L | 8.3 ppt | 🟠 Hard | reservoir |
| Medford, New York | 68 mg/L | 3.3 ppt | 🟡 Moderately Hard | reservoir |
National Benchmark
How Selden compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Selden | 102 mg/L | 🟡 Low |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Selden's Water Unique?
Local geology and source profile
Selden, New York, in Suffolk County — a suburban Suffolk County hamlet in the Town of Brookhaven, one of the most densely populated suburban communities in central Suffolk County — receives its municipal water from the Suffolk County Water Authority (SCWA), which draws from the Upper Glacial Aquifer (shallow Pleistocene Wisconsin glacial outwash sand) through SCWA wells in the Selden-Centereach corridor of central Suffolk County.
The moderately hard 102 mg/L hardness and TDS of 193 mg/L are softer than the deeper SCWA Magothy Aquifer supply zones (East Northport 174 mg/L, Lake Ronkonkoma 179 mg/L) — reflecting Selden's greater reliance on the Upper Glacial Aquifer (shallow Pleistocene outwash — less mineral contact time) compared to the deeper Cretaceous Magothy production zones. The Upper Glacial Aquifer in central Suffolk County provides relatively clean, moderately hard water — cleaner and softer than the deeper Magothy zones but slightly harder than pristine upper outwash zones with iron-reducing conditions.
At 102 mg/L, Selden's water is moderately hard — scale builds in kettles and appliances over months, dishwashers benefit from rinse aid, and faucet aerators need periodic cleaning. Quarterly descaling is appropriate. The PFAS level of 4.9 ppt warrants a certified drinking water filter — the Grumman Bethpage PFAS plume (Cretaceous aquifer PFAS from Grumman), Brookhaven National Laboratory (Upton, central Suffolk — a DOE nuclear research facility), and the Long Island defense-aviation PFAS legacy contribute to Selden's PFAS readings.
Geology & Source: Selden in Suffolk County draws from the Suffolk County Water Authority (SCWA) on the Upper Glacial Aquifer (Pleistocene outwash) — the Selden area of central Suffolk County draws primarily from the shallow Upper Glacial outwash sand — Long Island Pleistocene outwash aquifer produces moderately hard water at 102 mg/L with TDS 193 mg/L in this Suffolk County New York community.