Kailua 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
114.8 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, your appliances are currently losing 6% efficiency due to mineral buildup.
| Appliance | In Kailua | 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 compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Kailua, Hawaii | 42 mg/L | 1 ppt | 🟢 Soft | groundwater |
| Kaneohe, Hawaii | 60.5 mg/L | 1.2 ppt | 🟡 Moderately Hard | groundwater |
| Palolo, Hawaii | 27 mg/L | 0.8 ppt | 🟢 Soft | groundwater |
| Kuliouou - Kalani Iki, Hawaii | 57.5 mg/L | 1.2 ppt | 🟢 Soft | groundwater |
| Nuuanu - Punchbowl, Hawaii | 67.5 mg/L | 1.3 ppt | 🟡 Moderately Hard | groundwater |
National Benchmark
How Kailua compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Kailua | 42 mg/L | 🟢 None |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Kailua's Water Unique?
Local geology and source profile
Kailua, Hawaii, a community in Honolulu County on the windward (northeast) side of Oahu — one of the most desirable residential communities in Hawaii (Kailua consistently ranks among the most beautiful small towns and best beaches in the United States — Kailua Beach and Lanikai Beach are internationally acclaimed), home of Marine Corps Base Hawaii (Kaneohe Bay — MCBH Kaneohe Bay), a major Honolulu windward community known for outdoor recreation (kitesurfing, kayaking, windsurfing on Kailua Bay), and a popular high-end Hawaii residential community — draws its municipal water supply from the Ko'olau Basal Aquifer via the Honolulu Board of Water Supply (BWS). Water hardness in Kailua measures 42 mg/L — classified as very soft.
Kailua's very soft supply reflects the windward Oahu Ko'olau volcanic aquifer's calcareous-poor basaltic geology. The Ko'olau Basal Aquifer at Kailua draws from: the Ko'olau Basalt (Pleistocene tholeiitic basalt — calcareous-poor Fe-Mg silicate basalt with very low carbonate content); the Ko'olau Dike Zone (dense basaltic dike complex of the Ko'olau Volcano — calcareous-poor mafic intrusive). The heavy windward trade wind orographic rainfall recharges the Ko'olau basaltic aquifer, producing high-quality, soft water. BWS treatment of the calcareous-poor basalt aquifer produces the very soft 42 mg/L.
With hardness at 42 mg/L, Kailua residents enjoy very soft water. BWS consistently delivers water meeting all Hawaii DOH and EPA Safe Drinking Water Act requirements.
Geology & Source: Groundwater from the Ko'olau Basal Aquifer via the Honolulu Board of Water Supply (BWS) — the Honolulu County windward Oahu Kailua (Quaternary calcareous-poor Ko'olau Basalt — the windward Oahu basaltic volcanic aquifer; BWS Kailua district wells and distribution); very soft supply at 42 mg/L — reflecting windward Oahu's calcareous-poor Ko'olau volcanic basalt aquifer.