Waipio Water Hardness & Quality Report (2026)
Water Hardness
1.7 grains per gallon
Source
groundwater
pH Level
7.2
neutral = 7.0
Lead
0.003 mg/L
✓ Below action level
TDS
71.2 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 Waipio, your appliances are currently losing 4% efficiency due to mineral buildup.
| Appliance | In Waipio | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 8.7 yrs | 8.5 yrs | — |
| Washing Machine | 12.5 yrs | 12 yrs | — |
| Water Heater | 14.5 yrs | 15 yrs | -3% |
Regional Water Comparison
How Waipio compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Waipio, Hawaii | 28.5 mg/L | 0.8 ppt | 🟢 Soft | groundwater |
| Pearl City, Hawaii | 32.5 mg/L | 0.8 ppt | 🟢 Soft | groundwater |
| Waipahu, Hawaii | 28 mg/L | 0.8 ppt | 🟢 Soft | groundwater |
| Mililani Town, Hawaii | 67.5 mg/L | 1.3 ppt | 🟡 Moderately Hard | groundwater |
| Royal Kunia, Hawaii | 76.5 mg/L | 1.5 ppt | 🟡 Moderately Hard | groundwater |
National Benchmark
How Waipio compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Waipio | 28.5 mg/L | 🟢 None |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Waipio's Water Unique?
Local geology and source profile
Waipio, Hawaii, in Honolulu County — a Honolulu County census-designated place adjacent to Mililani and Waipahu on central Oahu — receives its water from the Honolulu Board of Water Supply, drawing from Koolau Range volcanic aquifer wells through the central Oahu distribution.
The ultra-soft 28.5 mg/L hardness and very low TDS of 71.2 mg/L make Waipio's water among the softest municipal supplies in the United States — the Quaternary Koolau Basalt is a highly insoluble olivine basalt formation, and the Waianae Basalt is similarly insoluble, with groundwater flowing through lava tubes at such speed that mineral dissolution is minimal (compare Mililani HI: 27/68 in Honolulu County comparable; Waipahu HI: 30/74 in Honolulu County comparable; Waipio consistent ultra-soft from the same Honolulu County Koolau volcanic basalt groundwater supply). The Koolau aquifer — Quaternary Koolau Basalt (insoluble — primary dilutant), Quaternary Waianae Basalt (insoluble — secondary dilutant), and Holocene Hawaiian basalt lava (insoluble — minimal TDS).
At 28.5 mg/L with TDS 71, Waipio has some of the softest and cleanest municipal water in America — virtually no scale buildup ever. The PFAS level of 0.8 ppt is exceptionally low — Waipio's pristine volcanic aquifer water is among the best quality in the nation. Review the Honolulu Board of Water Supply's annual water quality report.
Geology & Source: Waipio in Honolulu County draws from the Honolulu Board of Water Supply on Koolau volcanic aquifer (Honolulu County, central Oahu) — the Koolau Range at Oahu is developed in Quaternary Koolau Basalt (insoluble) and Quaternary Waianae Basalt (insoluble) — Hawaii Honolulu County Koolau volcanic basalt groundwater produces ultra-soft water at 28.5 mg/L with TDS 71.2 mg/L.