Pearl City Water Hardness & Quality Report (2026)
Water Hardness
1.9 grains per gallon
Source
groundwater
pH Level
7.3
neutral = 7.0
Lead
0.003 mg/L
✓ Below action level
TDS
83.2 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 Pearl City, your appliances are currently losing 4% efficiency due to mineral buildup.
| Appliance | In Pearl City | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 8.5 yrs | 8.5 yrs | — |
| Washing Machine | 12.4 yrs | 12 yrs | — |
| Water Heater | 14.3 yrs | 15 yrs | -5% |
Regional Water Comparison
How Pearl City compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Pearl City, Hawaii | 32.5 mg/L | 0.8 ppt | 🟢 Soft | groundwater |
| Waipahu, Hawaii | 28 mg/L | 0.8 ppt | 🟢 Soft | groundwater |
| Waimalu, Hawaii | 24 mg/L | 0.7 ppt | 🟢 Soft | groundwater |
| Royal Kunia, Hawaii | 76.5 mg/L | 1.5 ppt | 🟡 Moderately Hard | groundwater |
| Joint Base Pearl Harbor Hickam, Hawaii | 20 mg/L | 0.7 ppt | 🟢 Soft | groundwater |
National Benchmark
How Pearl City compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Pearl City | 32.5 mg/L | 🟢 None |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Pearl City's Water Unique?
Local geology and source profile
Pearl City, Hawaii, in Honolulu County on the shore of Pearl Harbor — a major Oahu central Oahu community, historically significant as the community adjacent to Pearl Harbor (site of the December 7, 1941 Japanese attack on the US Pacific Fleet), now a diverse middle-class residential community with major shopping (Pearlridge Center) and proximity to Joint Base Pearl Harbor–Hickam — draws its municipal water supply from the Pearl Harbor basal aquifer via the Honolulu Board of Water Supply (BWS). Water hardness in Pearl City measures 32.5 mg/L — classified as extremely soft.
Pearl City's extremely soft supply reflects Oahu's calcium-poor volcanic geology. The Pearl Harbor basal aquifer (Koolau Basalt basal freshwater lens — the major Honolulu groundwater supply) is recharged by direct rainfall on the Koolau Range (annual rainfall up to 300+ inches in the Koolau summit zone — among the wettest places on Earth). The Pliocene–Quaternary Koolau Basalt (tholeiitic ocean island basalt — calcium-moderate in the plagioclase fraction but dissolving minimally under Hawaii's rapid freshwater recharge) produces a remarkably soft basal freshwater lens. The Pearl Harbor basin's high-volume, rapid-recharge basalt aquifer maintains the extremely soft 32.5 mg/L at Pearl City taps.
With hardness at 32.5 mg/L, Pearl City residents enjoy some of the softest municipal water in the United States. Honolulu Board of Water Supply consistently delivers water meeting all Hawaii DOH and EPA Safe Drinking Water Act requirements.
Geology & Source: Groundwater from the Honolulu Board of Water Supply (BWS) Pearl Harbor basal aquifer and dike-impounded aquifer (Koolau Range) via the Honolulu BWS — the Honolulu District Pearl City–Aiea (Quaternary–Pliocene Koolau Basalt basal lens aquifer Pearl Harbor basin); extremely soft supply at 32.5 mg/L — reflecting Oahu's calcium-poor Koolau Basalt volcanic terrain.