How does Kihei's water compare to the national average?

The USA national average is 151 mg/L. Kihei (≈ 0–59 mg/L) is 121 mg/L softer than average.

Kihei Water Hardness & Quality Report (2026)

Water Hardness

soft

~0–59 mg/L

Soft

estimated · not lab-verified

Source

groundwater

pH Level

7.2

neutral = 7.0

Lead

0.002 mg/L

✓ Below action level

TDS

52.3 mg/L

Est. Daily Cost

$0.08

energy & soap waste

Source: See methodology section below · Updated 2026

soft~0–59 mg/LSoft · est.

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 Kihei, your appliances are currently losing 4% efficiency due to mineral buildup.

Appliance	In Kihei	Soft Water City	Efficiency Loss
Kettle	8.2 yrs	8.5 yrs	-4%
Washing Machine	11.5 yrs	12 yrs	-4%
Water Heater	14.4 yrs	15 yrs	-4%

Regional Water Comparison

How Kihei compares to its nearest neighbours

City	Hardness	PFAS (ppt)	Risk	Source
▶ Kihei, Hawaii	≈ 0–59 mg/L	0.7 ppt	🟢 Soft	groundwater
Kahului, Hawaii	≈ 0–60 mg/L	1 ppt	🟢 Soft	groundwater
Wailuku, Hawaii	≈ 120–179 mg/L	0 ppt	🟠 Hard	reservoir
Lahaina, Hawaii	≈ 0–60 mg/L	1 ppt	🟢 Soft	groundwater
Kailua-Kona, Hawaii	≈ 120–179 mg/L	1 ppt	🟠 Hard	groundwater

National Benchmark

How Kihei compares to the USA average

Benchmark	Hardness	Appliance Risk
▶ Kihei	≈ 0–59 mg/L	🟢 None
USA National Avg	151 mg/L	🟠 Moderate
Scarsdale Top Rated	0.02 mg/L	🟢 None

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What Makes Kihei's Water Unique?

Local geology and source profile

Source: GroundwaterTDS: 52.3 mg/LpH: 7.2

The Maui County Department of Water Supply serves Kihei, located in Central Maui, alongside Kahului, Wailuku, Waihee, Maalaea, and Paia. The primary water source is groundwater extracted from the Iao Aquifer beneath the West Maui Mountains. This supply is naturally filtered through lava rock layers and disinfected primarily with chlorine, then distributed via the Central Maui system. A small portion of filtered surface water is blended at the Iao Water Treatment Facility to augment supply during peak demand.

The Iao watershed encompasses the West Maui Mountains, where precipitation recharges the Iao Aquifer through fractured basaltic rock of volcanic origin. These Pleistocene-age lava flows and ash deposits form a porous basal groundwater system with high infiltration capacity. The volcanic geology imparts a very soft water character, as the rocks contribute few dissolved calcium or magnesium ions during natural filtration, unlike sedimentary carbonate formations that yield harder supplies.

Soft water minimizes scale buildup in pipes, water heaters, and appliances, reducing energy costs and maintenance needs. Dishwashers and washing machines operate efficiently without mineral deposits, and soap lathers readily without excess use. No water softener is needed — the naturally soft profile avoids hard water issues like spotting on glassware or clogged fixtures. Occasional cleaning with vinegar suffices for any minor deposits. Water quality meets all federal and state standards, with no notable violations for lead, copper, or PFAS reported per the 2025 Consumer Confidence Report.

Geology & Source: Iao Aquifer — Pleistocene basaltic lava flows and volcanic ash beneath the West Maui Mountains; fractured basalt is low in calcium and magnesium, producing naturally soft water

Other Hawaii Water Reports

Kahului

≈ 0–60 mg/L

🟢 Soft

Wailuku

≈ 120–179 mg/L

🟠 Hard

Lahaina

≈ 0–60 mg/L

🟢 Soft

Kailua-Kona

≈ 120–179 mg/L

🟠 Hard

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Notice an error or missing data? Help us keep this page accurate. If you spot incorrect water hardness, outdated utility info, or missing details, please let us know.

All reports are reviewed by our team. Thank you for supporting data quality!

Frequently Asked Questions

Is Kihei's water safe to drink?

Yes. Kihei's water meets all federal safety standards. The hardness is ≈ 0–59 mg/L (Soft), which is safe to drink. High hardness affects appliances and taste, but poses no health risk.

Do I need a water softener in Kihei?

Kihei's water is soft at ≈ 0–59 mg/L. A water softener is generally not necessary, though a carbon filter can improve taste and remove any remaining chlorine.

How does Kihei compare to the USA average?

The USA national average is 151 mg/L. Kihei (≈ 0–59 mg/L) is 121 mg/L below the national average. The softest major city is Scarsdale at just 0.02 mg/L.

Data Sources & Methodology

Water quality data for Kihei is derived from geographic and geological modelling of the surrounding region. No federal monitoring station data was available for this location.

Estimated

Water Hardness

Modelled estimate based on state-level USGS geological survey data for this region. No direct USGS Water Quality Portal measurement was matched to this city — the value reflects a statistical range calibrated to the state's dominant rock types and typical source water characteristics.

Estimated

Estimated from regional geology and source water characteristics. pH is correlated with water hardness and local bedrock — values may differ from utility-reported figures.

Estimated

TDS — Total Dissolved Solids

Estimated using a derived ratio from water hardness and regional conductance profiles. TDS in natural water correlates strongly with total mineral content including hardness ions.

Measured

PFAS — Perfluoroalkyl and Polyfluoroalkyl Substances

EPA UCMR5 (5th Unregulated Contaminant Monitoring Rule, 2023–2025) — sum of PFAS compounds detected at the public water system serving this city. A value of 0 indicates the system was sampled with no detection above reporting limits.

Modelled

Lead

Modelled estimate based on the EPA Lead and Copper Rule 90th-percentile tap-sample methodology. No publicly available per-city lead dataset with sufficient national coverage exists. Values are a conservative baseline derived from city population tier and infrastructure age — all estimates are maintained below the EPA action level of 0.015 mg/L.

Calculated

Appliance Lifespan

Calculated from water hardness using a linear degradation model. Baseline lifespans represent soft-water performance (kettle: 8.5 yrs, washing machine: 12.0 yrs, water heater: 15.0 yrs). Hard water mineral scale progressively reduces operational life in direct proportion to hardness concentration.