Water hardness in Hachinohe
132 mg/L hard
Tap water in Hachinohe is hard: 132 mg/L (7.7 gpg · 7.4 °dH · 13.2 °fH).
Source: Hachinohe Regional Water Supply Authority, tap-water quality results FY2025 (2025) · data checked 2026-10-21
Range across supply zones: 33–166 mg/L.
The Hachinohe authority takes water from the Mabuchi and Niida rivers and treats it at the Hakusan plant. The utility's 2025 data give 132.2 mg/L CaCO₃ within a range of 33.1 to 166.0 mg/L; the spread is wide, so the value at your tap depends on where in the supply area you live. Scale forms quickly in kettles, water heaters and pipes, so descaling is frequent and a softener is worth considering.
Japanese waterworks report hardness (硬度) in mg/L CaCO₃; the standard is 300 mg/L and the target 10–100 mg/L.
Water data
| Total hardness | 132 mg/L |
|---|---|
| Utility | Hachinohe Regional Water Supply Authority |
How Hachinohe compares
- Tap water in Hachinohe is 163 % harder than the median of the 228 cities we track in Japan (50 mg/L).
- By hardness it ranks 1 of 228 in Japan (1 = hardest); 100 % of these cities have softer water.
- Nearest city with clearly softer water: Aomori, 74 km away (55 mg/L).
Ranking of the hardest and softest water in Japan →
What it means at home
- Fast scale on taps, shower screens and kettle; white spots on glassware.
- Water heater: efficiency loss and element failures within years if unprotected.
- Dry skin and dull hair after showering are common.
- Softener recommended; jug or reverse osmosis for drinking.
How much salt will you use for softening?
Recommended, especially with a heater or boiler: scale cuts efficiency and shortens its life.
Descale a coffee machine or kettle about every 2 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Hachinohe
| Brand | Setting for this water |
|---|---|
| Bosch | H01 |
| Miele | 7 °dH |
| AEG / Electrolux | 2 |
| Beko | 2nd |
| Hoover | S1 |
| LG | H2 |
From each brand's manual for the model family named in the source; your model may differ, so check its manual. All brands and how to change the setting →
FAQ
Is Hachinohe water hard or soft?
It is hard: 132 mg/L as CaCO₃ (7.7 gpg, 7.4 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Hachinohe safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. Japanese waterworks report hardness (硬度) in mg/L CaCO₃; the standard is 300 mg/L and the target 10–100 mg/L.
How many grains per gallon is Hachinohe water?
7.7 gpg, equal to 7.4 °dH, 13.2 °fH or 132 mg/L calcium carbonate.
What dishwasher salt setting should I use in Hachinohe?
For 132 mg/L (7.4 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Hachinohe?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: Hachinohe Regional Water Supply Authority, tap-water quality results FY2025 (2025). Method: figure published by the water supplier. Hachinohe Regional Water Supply Authority, tap-water quality results FY2025 · Outdated figure? Tell us