Water hardness in Hawaii

Typical Hawaii tap water
55mg/L
3.2gpg
Soft

Population-weighted middle value across 24 Hawaii cities in the dataset

People with hard or very hard water
2%
Hardest
Wailuku 150
Softest
Pukalani 12

We have hardness numbers for 23 Hawaii cities; 3 of them are county estimates rather than utility figures. Each city page adds the water system's EPA violation record and a softener size for a typical household.

Every Hawaii city on the hardness scale
SoftModerately hardHardVery hard060120180240300360+Honolulu: 55 mg/LEast Honolulu: 105 mg/LHilo: 91 mg/LPearl City: 102 mg/LWaipahu: 55 mg/LKailua: 103 mg/LKaneohe: 105 mg/LKahului: 20 mg/LKihei: 51 mg/LWailuku: 150 mg/LEwa Beach: 102 mg/LWaimalu: 102 mg/LHalawa: 102 mg/LLahaina: 32 mg/LHickam Housing: 102 mg/LAiea: 102 mg/LAhuimanu: 105 mg/LPukalani: 12 mg/LKula: 12 mg/LWaimanalo: 105 mg/LIroquois Point: 102 mg/LKahaluu: 105 mg/LHeeia: 105 mg/LHonoluluEast HonoluluWaipahuKahuluiSoftMod.HardVery hard060120180240300360+Honolulu: 55 mg/LEast Honolulu: 105 mg/LHilo: 91 mg/LPearl City: 102 mg/LWaipahu: 55 mg/LKailua: 103 mg/LKaneohe: 105 mg/LKahului: 20 mg/LKihei: 51 mg/LWailuku: 150 mg/LEwa Beach: 102 mg/LWaimalu: 102 mg/LHalawa: 102 mg/LLahaina: 32 mg/LHickam Housing: 102 mg/LAiea: 102 mg/LAhuimanu: 105 mg/LPukalani: 12 mg/LKula: 12 mg/LWaimanalo: 105 mg/LIroquois Point: 102 mg/LKahaluu: 105 mg/LHeeia: 105 mg/LHonolulu

Dot size follows population. Tap a dot for the city page.

7Soft
15Moderately hard
1Hard
0Very hard

Hardest water in Hawaii

  1. Wailuku150
  2. East Honolulu105
  3. Kaneohe105
  4. Ahuimanu105
  5. Waimanalo105
  6. Kahaluu105
  7. Heeia105
  8. Kailua103

Softest water in Hawaii

  1. Kula12
  2. Pukalani12
  3. Kahului20
  4. Lahaina32
  5. Kihei51
  6. Waipahu55
  7. Honolulu55
  8. Hilo91

All cities in Hawaii

Citymg/LgpgClassDataEPA health violations
Honolulu553.2SoftCounty estimate–
East Honolulu1056.1Moderately hardUtility report0
Hilo915.3Moderately hardUtility report0
Pearl City1026.0Moderately hardUtility report0
Waipahu553.2SoftCounty estimate–
Kailua1036.0Moderately hardUtility report0
Kaneohe1056.1Moderately hardUtility report0
Kahului201.2SoftCounty estimate–
Kihei513.0SoftUtility report0
Wailuku1508.8HardUtility report0
Ewa Beach1026.0Moderately hardUtility report0
Waimalu1026.0Moderately hardUtility report0
Halawa1026.0Moderately hardUtility report0
Lahaina321.9SoftUtility report0
Hickam Housing1026.0Moderately hardUtility report0
Aiea1026.0Moderately hardUtility report0
Ahuimanu1056.1Moderately hardUtility report0
Pukalani120.7SoftUtility report0
Kula120.7SoftUtility report0
Waimanalo1056.1Moderately hardUtility report0
Iroquois Point1026.0Moderately hardUtility report0
Kahaluu1056.1Moderately hardUtility report0
Heeia1056.1Moderately hardUtility report0

Questions

Is Hawaii water hard?

The typical Hawaii resident gets about 55 mg/L (3.2 gpg), which is soft. About 2% of people in the cities we track have hard or very hard water.

Which city in Hawaii has the hardest water?

Among 23 cities with pages here, Wailuku is highest at 150 mg/L.

Which city in Hawaii has the softest water?

Pukalani, at 12 mg/L.

Other states

Hardness data: TapWaterData US Water Hardness, CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.