Kaka'ako 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
195.1 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 Kaka'ako, your appliances are currently losing 8% efficiency due to mineral buildup.
| Appliance | In Kaka'ako | 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 Kaka'ako compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Kaka'ako, Hawaii | 63 mg/L | 1.3 ppt | 🟡 Moderately Hard | groundwater |
| Downtown, Hawaii | 35 mg/L | 0.9 ppt | 🟢 Soft | groundwater |
| Honolulu, Hawaii | 67.5 mg/L | 1.3 ppt | 🟡 Moderately Hard | groundwater |
| Ala Moana - Kaka'ako, Hawaii | 66 mg/L | 1.3 ppt | 🟡 Moderately Hard | groundwater |
| Waikiki, Hawaii | 20 mg/L | 0.7 ppt | 🟢 Soft | groundwater |
National Benchmark
How Kaka'ako compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Kaka'ako | 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 Kaka'ako's Water Unique?
Local geology and source profile
Kaka'ako, Hawaii, in Honolulu County — a Honolulu County urban neighborhood adjacent to Downtown Honolulu and Ala Moana on the south Oahu waterfront — receives its water from the Honolulu Board of Water Supply, drawing from the Koolau Aquifer through the south Oahu distribution.
The soft 63 mg/L hardness and TDS of 195.1 mg/L reflect the Honolulu County supply's soft volcanic character — the Pliocene Koolau Basalt is largely insoluble, but Oahu's tropical weathering partially dissolves the island's deep residual soil and weathered basalt to produce slightly elevated TDS relative to hardness (compare Downtown Honolulu HI: 60/188 in Honolulu County comparable; Ala Moana HI: 65/202 in Honolulu County comparable; Kaka'ako consistent soft from the same Honolulu County Koolau Aquifer Pliocene basalt insoluble supply). The Koolau Aquifer — Pliocene Koolau Basalt (insoluble — primary dilutant), Quaternary Oahu residual soil (slightly calcareous — primary hardness contributor), and Holocene Oahu coastal alluvium (slightly calcareous — minor TDS).
At 63 mg/L with TDS 195, Kaka'ako'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 Honolulu. Review the Honolulu Board of Water Supply's annual water quality report.
Geology & Source: Kaka'ako in Honolulu County draws from the Honolulu Board of Water Supply on the Koolau Aquifer (Honolulu County, south Oahu Hawaii) — the Oahu volcanic aquifer draws from Pliocene Koolau Basalt (insoluble) and Quaternary Oahu residual soil (slightly calcareous) — Hawaii Honolulu County Koolau Aquifer Pliocene basalt insoluble supply produces soft water at 63 mg/L with TDS 195.1 mg/L.