Ronkonkoma Water Hardness & Quality Report (2026)
Water Hardness
4.1 grains per gallon
Source
reservoir
pH Level
7.4
neutral = 7.0
Lead
0.001 mg/L
✓ Below action level
TDS
110.3 mg/L
Est. Daily Cost
$0.19
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 Ronkonkoma, your appliances are currently losing 9% efficiency due to mineral buildup.
| Appliance | In Ronkonkoma | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 7.3 yrs | 8.5 yrs | -14% |
| Washing Machine | 11 yrs | 12 yrs | -8% |
| Water Heater | 12.8 yrs | 15 yrs | -15% |
Regional Water Comparison
How Ronkonkoma compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Ronkonkoma, New York | 70.5 mg/L | 3.4 ppt | 🟡 Moderately Hard | reservoir |
| Lake Ronkonkoma, New York | 179 mg/L | 8.5 ppt | 🟠 Hard | reservoir |
| Nesconset, New York | 153.5 mg/L | 7.3 ppt | 🟠 Hard | reservoir |
| Centereach, New York | 112.5 mg/L | 5.4 ppt | 🟡 Moderately Hard | reservoir |
| Saint James, New York | 109.5 mg/L | 5.3 ppt | 🟡 Moderately Hard | reservoir |
National Benchmark
How Ronkonkoma compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Ronkonkoma | 70.5 mg/L | 🟡 Low |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Ronkonkoma's Water Unique?
Local geology and source profile
Ronkonkoma, New York, in Suffolk County — an unincorporated Suffolk County community adjacent to Lake Ronkonkoma (the largest lake on Long Island) and Hauppauge, in the central Long Island corridor — receives its municipal water from the Suffolk County Water Authority (SCWA), drawing from the Upper Glacial Aquifer through shallow production wells beneath the central Suffolk County area.
The soft 70.5 mg/L hardness and low TDS of 110.3 mg/L reflect the central Suffolk County Upper Glacial Aquifer's Pleistocene outwash character. Ronkonkoma sits on the Ronkonkoma Terminal Moraine — the outermost recessional moraine deposited by the Wisconsin ice sheet, consisting of Pleistocene glaciofluvial sand and gravel (Cape Cod and Long Island formation). The Upper Glacial Aquifer beneath Ronkonkoma is a shallow, unconfined sand aquifer recharged by local precipitation through insoluble Pleistocene outwash, producing the soft, low-TDS water characteristic of central Long Island's water supply.
At 70.5 mg/L, Ronkonkoma's water is soft — essentially no scale forms, soap lathers abundantly, and appliances maintain good efficiency. Annual descaling is sufficient. The PFAS level of 3.4 ppt is good — Lake Ronkonkoma basin has limited direct military or major industrial PFAS sources. Brookhaven National Laboratory (Suffolk County, eastern Long Island — DOE nuclear research facility) and the Long Island MacArthur Airport (adjacent to Ronkonkoma — AFFF use) are the most notable nearby PFAS sources.
Geology & Source: Ronkonkoma in Suffolk County draws from Suffolk County Water Authority on the Upper Glacial Aquifer (Long Island, central Suffolk) — the Upper Glacial Aquifer consists of Pleistocene Ronkonkoma Terminal Moraine outwash sand and gravel — Long Island central Suffolk Pleistocene moraine outwash aquifer produces soft water at 70.5 mg/L with TDS 110 mg/L in this Suffolk County New York community.