Waimalu Water Hardness & Quality Report (2026)
Water Hardness
1.4 grains per gallon
Source
groundwater
pH Level
7.2
neutral = 7.0
Lead
0.002 mg/L
✓ Below action level
TDS
57.8 mg/L
Est. Daily Cost
$0.06
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 Waimalu, your appliances are currently losing 3% efficiency due to mineral buildup.
| Appliance | In Waimalu | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 8.8 yrs | 8.5 yrs | — |
| Washing Machine | 12.7 yrs | 12 yrs | — |
| Water Heater | 14.6 yrs | 15 yrs | -3% |
Regional Water Comparison
How Waimalu compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Waimalu, Hawaii | 24 mg/L | 0.7 ppt | 🟢 Soft | groundwater |
| Halawa, Hawaii | 44.5 mg/L | 1 ppt | 🟢 Soft | groundwater |
| Halawa Heights, Hawaii | 45 mg/L | 1 ppt | 🟢 Soft | groundwater |
| Aliamanu / Salt Lakes / Foster Village, Hawaii | 35 mg/L | 0.9 ppt | 🟢 Soft | groundwater |
| Pearl City, Hawaii | 32.5 mg/L | 0.8 ppt | 🟢 Soft | groundwater |
National Benchmark
How Waimalu compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Waimalu | 24 mg/L | 🟢 None |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Waimalu's Water Unique?
Local geology and source profile
Waimalu, Hawaii, in Honolulu County — an unincorporated Honolulu County community adjacent to Pearl City and Aiea in the Pearl Harbor area of south Oahu — receives its water from the Honolulu Board of Water Supply, drawing from the Pearl Harbor Aquifer (Honolulu County) through the south Oahu distribution.
The very soft 24 mg/L hardness and very low TDS of 57.8 mg/L are consistent with the Hawaiian volcanic aquifer supplies (compare Halawa: 26.5 mg/L — adjacent Pearl Harbor area) — reflecting the Pearl Harbor basalt aquifer's insoluble volcanic basalt geology that yields almost no calcareous or mineral dissolution. The Pearl Harbor Aquifer at Honolulu County — Quaternary Schofield Basalt (insoluble — primary dilutant, dominant character), Quaternary Koolau Basalt (insoluble — dilutant), and Quaternary alluvial cap deposits (minor trace contributor).
At 24 mg/L, Waimalu's water is very soft — no scale buildup, appliances last their full service life, and no softening is needed. Water is safe for all uses. The PFAS level of 0.7 ppt is well below the EPA advisory threshold — one of the lowest readings in this entire dataset. Standard carbon block filter is sufficient for drinking water quality in Waimalu.
Geology & Source: Waimalu in Honolulu County draws from the Honolulu Board of Water Supply on the Pearl Harbor Aquifer (Honolulu County, south Oahu, Hawaii) — the Pearl Harbor Aquifer is developed in Quaternary Pleistocene Schofield Basalt (insoluble) — Hawaii Honolulu County Pearl Harbor Basalt crystalline volcanic aquifer produces very soft water at 24 mg/L with TDS 57.8 mg/L.