Derby Water Hardness & Quality Report (2026)
Water Hardness
1.8 grains per gallon
Source
reservoir
pH Level
7.2
neutral = 7.0
Lead
0.002 mg/L
✓ Below action level
TDS
53.2 mg/L
Est. Daily Cost
$0.08
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 Derby, your appliances are currently losing 4% efficiency due to mineral buildup.
| Appliance | In Derby | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 8.6 yrs | 8.5 yrs | — |
| Washing Machine | 12.5 yrs | 12 yrs | — |
| Water Heater | 14.4 yrs | 15 yrs | -4% |
Regional Water Comparison
How Derby compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Derby, Connecticut | 31 mg/L | 6 ppt | 🟢 Soft | reservoir |
| Shelton, Connecticut | 25 mg/L | 5.4 ppt | 🟢 Soft | reservoir |
| Ansonia, Connecticut | 25.5 mg/L | 5.5 ppt | 🟢 Soft | reservoir |
| Orange, Connecticut | 17.5 mg/L | 4.8 ppt | 🟢 Soft | reservoir |
| Seymour, Connecticut | 22.5 mg/L | 5.2 ppt | 🟢 Soft | reservoir |
National Benchmark
How Derby compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Derby | 31 mg/L | 🟢 None |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Derby's Water Unique?
Local geology and source profile
Derby, Connecticut, in Naugatuck Valley — a Naugatuck Valley Planning Region city adjacent to Shelton and Ansonia on the Naugatuck River in south-central Connecticut — receives its water from the Connecticut Water company, drawing from Lake Housatonic or Naugatuck River watershed (Naugatuck Valley) through the south-central Connecticut distribution.
The very soft 31 mg/L hardness and very low TDS of 53.2 mg/L make Derby one of the softest water communities in this dataset — reflecting the Naugatuck-Housatonic watershed's Precambrian Monson Gneiss and minimal Cambrian Stockbridge Marble calcareous contact, producing very soft water comparable to Greenwich CT (33.5/58.6) and Shadow Hills CA (33.5/67.4). The Naugatuck-Housatonic watershed — Precambrian Monson Gneiss (insoluble — primary dilutant), Cambrian Stockbridge Marble (slightly calcareous — minor hardness contributor), and Pleistocene Connecticut glacial drift (insoluble — secondary dilutant).
At 31 mg/L, Derby's water is very soft — scale forms very slowly in appliances, dishwashers remain efficient, and no softening is needed. Annual descaling is appropriate. The PFAS level of 6.0 ppt warrants a certified drinking water filter — the Naugatuck Valley south-central Connecticut industrial corridor (former brass mills) contribute to Derby's elevated PFAS readings.
Geology & Source: Derby in Naugatuck Valley draws from the Connecticut Water on Lake Housatonic or Naugatuck River watershed (Naugatuck Valley Planning Region, south-central Connecticut) — the Naugatuck-Housatonic watershed drains Precambrian Monson Gneiss (insoluble) and Cambrian Stockbridge Marble (slightly calcareous) — Connecticut Naugatuck Valley Housatonic Precambrian-Cambrian insoluble supply produces very soft water at 31 mg/L with TDS 53.2 mg/L.