Water hardness in Nagoya
19 mg/L soft
Tap water in Nagoya is soft: 19 mg/L (1.1 gpg · 1 °dH · 1.9 °fH).
Source: 名古屋市上下水道局 Nagoya City Waterworks & Sewerage Bureau, tap-water quality results FY2025 (2025) · data checked 2026-10-21
Range across supply zones: 15–26 mg/L.
Nagoya takes its water from the Kiso River at the Inuyama and Asahi intakes and treats it at the Kasugai, Nabeya-Ueno and Ōji plants. The utility's 2025 data give 18.5 mg/L CaCO₃ within a range of 15.0 to 26.0 mg/L. Water this soft rarely leaves scale, so kettles and showerheads stay mostly clear and a softener adds little.
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 | Nagoya City Waterworks & Sewerage Bureau |
How Nagoya compares
- Tap water in Nagoya 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 Aichi it is number 7 of 8 cities; the regional median is 20 mg/L.
- Nearest city with clearly softer water: Toyota, 25 km away (11 mg/L).
- Nearest city with clearly harder water: Ichinomiya, 16 km away (47 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 Nagoya
| 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 Nagoya 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 Nagoya 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 Nagoya 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 Nagoya?
For 19 mg/L (1 °dH) check your manufacturer's table: level 0–1, usually no salt.
Do I need a water softener in Nagoya?
No. With soft water a softener adds nothing.
Source
Source: 名古屋市上下水道局 Nagoya City Waterworks & Sewerage Bureau, tap-water quality results FY2025 (2025). Method: figure published by the water supplier. 名古屋市上下水道局 Nagoya City Waterworks & Sewerage Bureau, tap-water quality results FY2025 · Outdated figure? Tell us