Makakilo / Kapolei / Honokai Hale Water Hardness & Quality Report (2026)
Water Hardness
2.1 grains per gallon
Source
groundwater
pH Level
7.3
neutral = 7.0
Lead
0.004 mg/L
✓ Below action level
TDS
92.8 mg/L
Est. Daily Cost
$0.09
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 Makakilo / Kapolei / Honokai Hale, your appliances are currently losing 5% efficiency due to mineral buildup.
| Appliance | In Makakilo / Kapolei / Honokai Hale | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 8.4 yrs | 8.5 yrs | -1% |
| Washing Machine | 12.3 yrs | 12 yrs | — |
| Water Heater | 14.2 yrs | 15 yrs | -5% |
Regional Water Comparison
How Makakilo / Kapolei / Honokai Hale compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Makakilo / Kapolei / Honokai Hale, Hawaii | 35.5 mg/L | 0.9 ppt | 🟢 Soft | groundwater |
| Makakilo City, Hawaii | 55 mg/L | 1.2 ppt | 🟢 Soft | groundwater |
| Makakilo, Hawaii | 75.5 mg/L | 1.5 ppt | 🟡 Moderately Hard | groundwater |
| Kapolei, Hawaii | 49 mg/L | 1.1 ppt | 🟢 Soft | groundwater |
| 'Ewa Gentry, Hawaii | 38 mg/L | 0.9 ppt | 🟢 Soft | groundwater |
National Benchmark
How Makakilo / Kapolei / Honokai Hale compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Makakilo / Kapolei / Honokai Hale | 35.5 mg/L | 🟢 None |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Makakilo / Kapolei / Honokai Hale's Water Unique?
Local geology and source profile
Makakilo/Kapolei/Honokai Hale, Hawaii, in Honolulu County on western Oahu — the Kapolei–Makakilo–Honokai Hale community zone on the Ewa Plain, Oahu's 'Second City' (planned as a major growth center to relieve Honolulu congestion), home of major state government offices, University of Hawaii West Oahu (UHWO), and a rapidly growing diverse suburban community in the Ko Olina and Kapolei resort-residential corridor — draws its municipal water supply from the Ewa Aquifer System via the Honolulu Board of Water Supply (BWS) Ewa District. Water hardness in Makakilo/Kapolei/Honokai Hale measures 35.5 mg/L — classified as extremely soft.
Makakilo/Kapolei's extremely soft supply reflects the western Oahu volcanic geology. The Ewa Aquifer (the basal freshwater lens of the Pliocene–Quaternary Waianae Basalt — the older of Oahu's two volcanic shields) is recharged by rainfall on the Waianae and Koolau Ranges. While the Waianae Range is the more calcareous of Oahu's volcanic shield terrains (older Waianae Basalt has slightly more plagioclase than Koolau Basalt), the basalt aquifer's calcium content is still very low. The Ewa Aquifer basal freshwater lens maintains the extremely soft 35.5 mg/L — among the softest water supplies in the United States.
With hardness at 35.5 mg/L, Makakilo/Kapolei residents enjoy very soft water. Honolulu Board of Water Supply consistently delivers water meeting all Hawaii DOH and EPA Safe Drinking Water Act requirements.
Geology & Source: Groundwater from the Ewa Aquifer System (Oahu basal lens) via the Honolulu Board of Water Supply (BWS) Ewa District — the Honolulu County Ewa Plain (Pliocene–Quaternary Waianae and Koolau Basalt basal freshwater lens aquifer); extremely soft supply at 35.5 mg/L — reflecting Oahu's calcium-poor volcanic terrain.