Water hardness in Hawaii, characterized by the concentration of dissolved minerals like calcium and magnesium, differs notably from many other states due to the islands’ unique volcanic geology. Unlike areas with sedimentary rocks that contribute to hard water, Hawaii’s volcanic rock results in generally softer water across the islands.
In Hawaii, water is typically classified as soft to moderately hard. The groundwater, which is a primary source of water for the islands, typically has lower mineral content because it filters through porous volcanic rock, which does not contribute significantly to mineralization. This geology is starkly different from places like Nevada, where water hardness is influenced by limestone and other hard rock formations.
The softer nature of water in Hawaii means that residents generally face fewer issues related to the effectiveness of soaps and detergents and less impact on plumbing systems and the lifespan of water-using appliances. However, monitoring water quality remains important for ensuring that water meets household and industrial needs.
In the provided data, the water hardness levels in Hawaii show that most cities have not reported specific values for water hardness, indicating either unmeasured or relatively insignificant levels. However, among the cities for which data is reported, the highest water hardness levels are recorded in Waimea CDP, with a hardness level of 165 ppm (9.6 gpg). Other areas with notable measured hardness include Hanamaulu at 125 ppm (7.3 gpg), Princeville at 125 ppm (7.3 gpg), and Kekaha at 165 ppm (9.6 gpg).
City | Hardness ppm (mg/L) | Hardness gpg | Information Source | Notes |
Urban Honolulu | n/a | n/a | Link | Link |
East Honolulu | n/a | n/a | Link | Link |
Hilo | n/a | n/a | Link | |
Pearl City | n/a | n/a | Link | Link |
Kailua CDP | n/a | n/a | Link | Link |
Waipahu | n/a | n/a | Link | Link |
Kaneohe | n/a | n/a | Link | Link |
Mililani Town | n/a | n/a | Link | Link |
Kahului | n/a | n/a | Link | |
Ewa Gentry | n/a | n/a | Link | Link |
Kapolei | n/a | n/a | Link | Link |
Kihei | n/a | n/a | Link | |
Mililani Mauka | n/a | n/a | Link | Link |
Kailua CDP | n/a | n/a | Link | Link |
Makakilo | n/a | n/a | Link | Link |
Schofield Barracks | n/a | n/a | Link | |
Wahiawa | n/a | n/a | Link | Link |
Wailuku | n/a | n/a | Link | |
Ocean Pointe | n/a | n/a | Link | Link |
Ewa Beach | n/a | n/a | Link | Link |
Halawa | n/a | n/a | Link | Link |
Waimalu | n/a | n/a | Link | Link |
Royal Kunia | n/a | n/a | Link | Link |
Waianae | n/a | n/a | Link | Link |
Hawaiian Paradise Park | n/a | n/a | Link | |
Lahaina | n/a | n/a | Link | |
Nanakuli | n/a | n/a | Link | Link |
Maili | n/a | n/a | Link | Link |
Kaiminani | n/a | n/a | Link | Link |
Kaneohe Base | n/a | n/a | Link | |
Waipio | n/a | n/a | Link | Link |
Waihee-Waiehu | n/a | n/a | Link | |
Kapaa | 90.0 | 5.3 | Link | |
Waimea CDP | 165.0 | 9.6 | Link | |
Makaha | n/a | n/a | Link | Link |
Aiea | n/a | n/a | Link | Link |
Hickam Housing | n/a | n/a | Link | |
Haiku-Pauwela | n/a | n/a | Link | |
Ahuimanu | n/a | n/a | Link | Link |
Lihue | 90.0 | 5.3 | Link | |
Pukalani | n/a | n/a | Link | |
Makawao | n/a | n/a | Link | |
Waikele | n/a | n/a | Link | Link |
Waikoloa Village | n/a | n/a | Link | |
Wailua Homesteads | n/a | n/a | Link | |
Kahaluu-Keauhou | n/a | n/a | Link | |
Napili-Honokowai | n/a | n/a | Link | |
Kula | n/a | n/a | Link | |
Ewa Villages | n/a | n/a | Link | Link |
Wailea | n/a | n/a | Link | |
West Loch Estate | n/a | n/a | Link | Link |
Iroquois Point | n/a | n/a | Link | Link |
Waimanalo | n/a | n/a | Link | Link |
Laie | n/a | n/a | Link | No address appeared in search here. Looks like resort town. |
Waipio Acres | n/a | n/a | Link | Link |
Pupukea | n/a | n/a | Link | Link |
Kahaluu | n/a | n/a | Link | Link |
East Kapolei | n/a | n/a | Link | Link |
Heeia | n/a | n/a | Link | Link |
Haleiwa | n/a | n/a | Link | |
Kalaheo | 90.0 | 5.3 | Link | |
Hanamaulu | 125.0 | 7.3 | Link | Princeville area |
Waimanalo Beach | n/a | n/a | Link | Link |
Captain Cook | n/a | n/a | Link | South Kona |
Puhi | 90.0 | 5.3 | Link | Lihue Kapaa |
Whitmore Village | n/a | n/a | Link | |
Waikapu | n/a | n/a | Link | |
Hawaiian Beaches | n/a | n/a | Link | Pahoa |
Ainaloa | n/a | n/a | Link | Pahoa |
Mountain View | n/a | n/a | Link | Pahoa |
Hauula | n/a | n/a | Link | Link |
Hawaiian Ocean View | n/a | n/a | Link | |
Kaunakakai | n/a | n/a | Link | |
Hawaiian Acres | n/a | n/a | Link | Pahoa |
Kilauea | 67.5 | 3.9 | Link | |
Helemano | n/a | n/a | Link | No CCRs appear in address search |
Lanai City | n/a | n/a | Link | |
Kekaha | 165.0 | 9.6 | Link | Kehaka |
Holualoa | n/a | n/a | Link | North Kona |
Waialua | n/a | n/a | Link | Link |
Kalaeloa | n/a | n/a | Link | |
Lawai | 90.0 | 5.3 | Link | Kalaheo Lawai |
Kurtistown | n/a | n/a | Link | Olaa |
Keokea | n/a | n/a | Link | |
Anahola | 45.0 | 2.6 | Link | |
Honaunau-Napoopoo | n/a | n/a | Link | South Kona |
Wailua | 90.0 | 5.3 | Link | Lihue Kapaa |
Orchidlands Estates | n/a | n/a | Link | Pahoa |
Honokaa | n/a | n/a | Link | Haina |
Koloa | 90.0 | 5.3 | Link | Kalaheo Lawai |
Kahuku | n/a | n/a | Link | Link |
Eleele | 80.0 | 4.7 | Link | Hanapepe Eleele |
Hanapepe | 80.0 | 4.7 | Link | Hanapepe Eleele |
Wheeler AFB | n/a | n/a | Link | Schofield Barracks |
Paia | n/a | n/a | Link | |
Kealakekua | n/a | n/a | Link | South Kona |
Kualapuu | n/a | n/a | Link | |
Maunawili | n/a | n/a | Link | Link |
Princeville | 125.0 | 7.3 | Link | Princeville area |
Kapaau | n/a | n/a | Link | North Kohala |
ppm = Parts Per Million
mg/L = Milligrams Per Liter
gpg = Grains Per Gallon
Hard water can cause issues such as mineral buildup in plumbing and appliances, reduce the efficacy of soaps and detergents, and affect the taste of the water. A tried and true solution is the use of a water softener. A water softener, like the ones from DROP, could be a worthwhile investment.
These devices work by replacing the calcium and magnesium ions that cause hardness with sodium ions, resulting in softer water. With innovative features, easy installation, and efficient operation, DROP smart water softeners provide a solution to hard water issues, extending the lifespan of appliances, improving water taste, enhancing soap effectiveness, reducing scale build-up, and increasing the overall water efficiency in your home.