Kailua-Kona Water Hardness & Quality Report (2026)
Water Hardness
2.5 grains per gallon
Source
groundwater
pH Level
7.4
neutral = 7.0
Lead
0.005 mg/L
✓ Below action level
TDS
116.6 mg/L
Est. Daily Cost
$0.11
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 Kailua-Kona, your appliances are currently losing 6% efficiency due to mineral buildup.
| Appliance | In Kailua-Kona | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 8.2 yrs | 8.5 yrs | -4% |
| Washing Machine | 12 yrs | 12 yrs | — |
| Water Heater | 13.9 yrs | 15 yrs | -7% |
Regional Water Comparison
How Kailua-Kona compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Kailua-Kona, Hawaii | 42.5 mg/L | 1 ppt | 🟢 Soft | groundwater |
| Hilo, Hawaii | 60.5 mg/L | 1.2 ppt | 🟡 Moderately Hard | groundwater |
| Hawaiian Paradise Park, Hawaii | 57.5 mg/L | 1.2 ppt | 🟢 Soft | groundwater |
| Kihei, Hawaii | 22 mg/L | 0.7 ppt | 🟢 Soft | groundwater |
| Kahului, Hawaii | 40 mg/L | 1 ppt | 🟢 Soft | groundwater |
National Benchmark
How Kailua-Kona compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Kailua-Kona | 42.5 mg/L | 🟢 None |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
Bring Badger-quality water to your Kailua-Kona home
Shop water softeners on Amazon.com →
What Makes Kailua-Kona's Water Unique?
Local geology and source profile
Kailua-Kona, Hawaii, in Hawaii County — a Hawaii County census-designated place on the Kona coast of the Big Island, adjacent to Captain Cook and Holualoa in west Hawaii — receives its water from the Department of Water Supply of Hawaii County, drawing from groundwater wells developed in the Kona volcanic aquifer through the west Hawaii distribution.
The very soft 42.5 mg/L hardness and low TDS of 116.6 mg/L reflect the Kona coast volcanic aquifer supply's very soft character — the Quaternary Mauna Loa Basalt and Hualalai Basalt are both highly insoluble olivine basaltic formations, with groundwater moving rapidly through lava tubes and fissures with minimal rock-water contact time for mineral dissolution (compare Captain Cook HI: 40/112 in Hawaii County comparable; Waimea HI: 44/120 in Hawaii County comparable; Kailua-Kona consistent very soft from the same Hawaii County Kona volcanic basalt groundwater supply). The Kona aquifer — Quaternary Mauna Loa Basalt (insoluble — primary dilutant), Quaternary Hualalai Basalt (insoluble — secondary dilutant), and Holocene lava tube water (insoluble — minimal TDS).
At 42.5 mg/L with TDS 117, Kailua-Kona's water is very soft — virtually no scale buildup. The PFAS level of 1.0 ppt is exceptionally low — Kailua-Kona has some of the cleanest water in the United States, reflecting Hawaii's pristine volcanic aquifer environment. Review the Hawaii County Department of Water Supply annual report for the latest data.
Geology & Source: Kailua-Kona in Hawaii County draws from the Department of Water Supply on Kona coast groundwater (Hawaii County, west Hawaii Island) — the Kona coast at Hawaii County is developed in Quaternary Mauna Loa Basalt (insoluble) and Quaternary Hualalai Basalt (insoluble) — Hawaii Hawaii County Kona volcanic basalt groundwater produces very soft water at 42.5 mg/L with TDS 116.6 mg/L.