Kihei, HI water hardness

Tap water hardness
51mg/L
3.0gpg
Soft

Reported by Maui Highlands · April 2025

HI typical
55 mg/L
EPA health violations since 2016
0
Data
Utility report

Kihei water measures 51 mg/L (3.0 gpg) of hardness, soft by USGS standards. The number comes from Maui Highlands, dated April 2025.

Kihei on the hardness scale, with nearby cities
060120180240300360+HI typical 55Kula: 12 mg/LKula 12Pukalani: 12 mg/LPukalani 12Kahului: 20 mg/LKahului 20Lahaina: 32 mg/LLahaina 32Honolulu: 55 mg/LHonolulu 55Kailua: 103 mg/LKailua 103East Honolulu: 105 mg/LEast Honolulu 105Waimanalo: 105 mg/LWaimanalo 105Kaneohe: 105 mg/LKaneohe 105Wailuku: 150 mg/LWailuku 150Kihei 51mg/L as calcium carbonate060120180240300360+HI 55Kula: 12 mg/LKula 12Pukalani: 12 mg/LPukalani 12Kahului: 20 mg/LKahului 20Lahaina: 32 mg/LLahaina 32East Honolulu: 105 mg/LEast Honol. 105Wailuku: 150 mg/LWailuku 15051 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

At 51 mg/L, Kihei is close to the typical Hawaii figure of 55 mg/L. Of the 10 nearest cities we track, 4 have softer water and 6 have harder. The range nearby runs from 12 mg/L in Kula to 150 in Wailuku.

What 51 mg/L means at home

Soap and shampoo lather with very little product. Kettles and showerheads stay mostly free of white crust.

Some people notice that soap feels slow to rinse off in soft water. That slippery feel is normal and harmless.

Hardness is not a health problem, and EPA sets no limit for it. It is a matter of scale and soap.

What to do about it

Nothing, as far as hardness goes. At 51 mg/L a softener would have almost nothing to remove.

Carbon filter

If the water tastes of chlorine, a pitcher or faucet carbon filter takes care of that. It does not change hardness.

EPA record for Kihei's water system

Maui Highlands · PWSID HI0000256

No health-based violations since 2016

Serves about 26 people from groundwater.

Health-based
0
Monitoring or reporting
0
Open now
0

Health-based means a contaminant above its legal limit or a missed treatment step. Monitoring and reporting violations are late or missing tests and notices. Source: EPA ECHO, 2026Q3 export, violations with periods starting 2016 or later. Full EPA record.

Questions

Is Kihei water hard?

No. It measures about 51 mg/L (3.0 grains per gallon), which the USGS classes as soft.

What is the water hardness in Kihei in grains per gallon?

About 3.0 gpg. One grain per gallon equals 17.1 mg/L, so 51 mg/L divided by 17.1 gives 3.0.

Has the Kihei water system had EPA violations?

EPA records show no health-based violations for Maui Highlands since 2016.

Nearby cities

All 23 cities in Hawaii

Hardness data: TapWaterData US Water Hardness (utility report, April 16, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.