Water hardness in Hitachi
36 mg/L soft
Tap water in Hitachi is soft: 36 mg/L (2.1 gpg · 2 °dH · 3.6 °fH).
Source: Hitachi City Enterprise Bureau, 給水栓水検査結果 令和8年8月 (2026-08) · data checked 2026-11-07
Range across supply zones: 22–164 mg/L.
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 | 36 mg/L |
|---|---|
| Utility | 日立市企業局 Hitachi City Enterprise Bureau (waterworks) |
How Hitachi compares
- Tap water in Hitachi is 28 % softer than the median of the 228 cities we track in Japan (50 mg/L).
- By hardness it ranks 190 of 228 in Japan (1 = hardest); 15 % of these cities have softer water.
- In Ibaraki it is number 3 of 3 cities; the regional median is 56 mg/L.
- Nearest city with clearly softer water: Fukushima, 129 km away (16 mg/L).
- Nearest city with clearly harder water: Mito, 33 km away (56 mg/L).
Ranking of the hardest and softest water in Japan →
What it means at home
- Little or no limescale in kettles, water heaters or washing machines.
- Soap lathers easily; water does not dry skin or hair.
- Dishwasher: salt setting at minimum or off.
- No softener needed; a jug filter only changes taste.
How much salt will you use for softening?
No. Water this soft does not need softening.
Descale a coffee machine or kettle about every 6 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Hitachi
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 2 °dH |
| AEG / Electrolux | 1 |
| Beko | 1st |
| Hoover | S0 |
| LG | H0 |
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 Hitachi water hard or soft?
It is soft: 36 mg/L as CaCO₃ (2.1 gpg, 2 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Hitachi 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 Hitachi water?
2.1 gpg, equal to 2 °dH, 3.6 °fH or 36 mg/L calcium carbonate.
What dishwasher salt setting should I use in Hitachi?
For 36 mg/L (2 °dH) check your manufacturer's table: level 0–1, usually no salt.
Do I need a water softener in Hitachi?
No. With soft water a softener adds nothing.
Source
Source: Hitachi City Enterprise Bureau, 給水栓水検査結果 令和8年8月 (2026-08). Method: figure published by the water supplier. Hitachi City Enterprise Bureau, 給水栓水検査結果 令和8年8月 · Outdated figure? Tell us