Water hardness in Niigata
19 mg/L soft
Tap water in Niigata is soft: 19 mg/L (1.1 gpg · 1 °dH · 1.9 °fH).
Source: 新潟市水道局 Niigata City Waterworks Bureau, water quality annual report (tap water) FY2025 (2025) · data checked 2026-10-21
Range across supply zones: 12–49 mg/L.
Niigata takes surface water from four rivers: the Shinano, Agano, Nakanokuchi and Nishi. The utility's 2025 data give 18.5 mg/L CaCO₃ within a range of 12.0 to 49.0 mg/L; the spread is wide, so the value at your tap depends on where in the supply area you live. At this level scale is rarely a problem, soap lathers easily and a softener is unnecessary.
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 | 19 mg/L |
|---|---|
| Utility | Niigata City Waterworks Bureau |
How Niigata compares
- Tap water in Niigata is 63 % softer than the median of the 228 cities we track in Japan (50 mg/L).
- By hardness it ranks 223 of 228 in Japan (1 = hardest); 2 % of these cities have softer water.
- In Niigata it is number 3 of 3 cities; the regional median is 33 mg/L.
- Nearest city with clearly harder water: Nagaoka, 55 km away (35 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 Niigata
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 1 °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 Niigata water hard or soft?
It is soft: 19 mg/L as CaCO₃ (1.1 gpg, 1 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Niigata 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 Niigata water?
1.1 gpg, equal to 1 °dH, 1.9 °fH or 19 mg/L calcium carbonate.
What dishwasher salt setting should I use in Niigata?
For 19 mg/L (1 °dH) check your manufacturer's table: level 0–1, usually no salt.
Do I need a water softener in Niigata?
No. With soft water a softener adds nothing.
Source
Source: 新潟市水道局 Niigata City Waterworks Bureau, water quality annual report (tap water) FY2025 (2025). Method: figure published by the water supplier. 新潟市水道局 Niigata City Waterworks Bureau, water quality annual report (tap water) FY2025 · Outdated figure? Tell us