Kapa'a Water Hardness & Quality Report (2026)
Water Hardness
3.7 grains per gallon
Source
groundwater
pH Level
7.6
neutral = 7.0
Lead
0.007 mg/L
✓ Below action level
TDS
195.5 mg/L
Est. Daily Cost
$0.17
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 Kapa'a, your appliances are currently losing 8% efficiency due to mineral buildup.
| Appliance | In Kapa'a | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 7.5 yrs | 8.5 yrs | -12% |
| Washing Machine | 11.3 yrs | 12 yrs | -6% |
| Water Heater | 13.1 yrs | 15 yrs | -13% |
Regional Water Comparison
How Kapa'a compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Kapa'a, Hawaii | 63 mg/L | 1.3 ppt | 🟡 Moderately Hard | groundwater |
| Waianae, Hawaii | 15 mg/L | 0.6 ppt | 🟢 Soft | groundwater |
| Nanakuli, Hawaii | 76 mg/L | 1.5 ppt | 🟡 Moderately Hard | groundwater |
| Schofield Barracks, Hawaii | 76.5 mg/L | 1.5 ppt | 🟡 Moderately Hard | groundwater |
| Wahiawa, Hawaii | 77.5 mg/L | 1.5 ppt | 🟡 Moderately Hard | groundwater |
National Benchmark
How Kapa'a compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Kapa'a | 63 mg/L | 🟡 Low |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Kapa'a's Water Unique?
Local geology and source profile
Kapa'a, Hawaii, in Kauai County — a Kauai County town adjacent to Lihu'e and Wailua on the Coconut Coast of east Kauai — receives its water from the County of Kauai Department of Water, drawing from the Wailua River watershed and local groundwater through the east Kauai distribution.
The soft 63 mg/L hardness and TDS of 195.5 mg/L reflect the Kauai County supply's soft volcanic character — the Pliocene Waimea Canyon Basalt is largely insoluble, but Kauai's heavy tropical rainfall partially dissolves the island's deep residual soil and weathered basalt to produce slightly elevated TDS relative to hardness (compare Lihu'e HI: 60/188 in Kauai County comparable; Wailua HI: 65/202 in Kauai County comparable; Kapa'a consistent soft from the same Kauai County Wailua River Pliocene basalt insoluble supply). The Wailua watershed — Pliocene Waimea Canyon Basalt (insoluble — primary dilutant), Quaternary Kauai residual soil (slightly calcareous — primary hardness contributor), and Holocene Wailua River alluvium (slightly calcareous — minor TDS).
At 63 mg/L with TDS 196, Kapa'a's water is soft — minimal scale buildup. Annual descaling is appropriate. The PFAS level of 1.3 ppt is very low — an excellent result for Kauai. Review the Kauai County Department of Water's annual water quality report.
Geology & Source: Kapa'a in Kauai County draws from the Kauai County Water on the Wailua River watershed (Kauai County, east Kauai Hawaii) — the Kauai volcanic watershed draws from Pliocene Waimea Canyon Basalt (insoluble) and Quaternary Kauai residual soil (slightly calcareous) — Hawaii Kauai County Wailua River Pliocene basalt insoluble supply produces soft water at 63 mg/L with TDS 195.5 mg/L.