Water hardness in Tokushima
44 mg/L soft
Tap water in Tokushima is soft: 44 mg/L (2.6 gpg · 2.5 °dH · 4.4 °fH).
Source: 徳島市上下水道局 Tokushima City Waterworks & Sewerage Bureau, tap-water quality results FY2025 (上下水道事業年報 水道水質編) (2025) · data checked 2026-10-21
Range across supply zones: 36–68 mg/L.
Tokushima's tap water is supplied by Tokushima City Waterworks & Sewerage Bureau; the intake mix is not confirmed here, but piped water in Tokushima Prefecture comes mainly from rivers and reservoirs fed by short, steep catchments. Hardness is reported at 44.2 mg/L CaCO₃, ranging from 36.0 to 68.0 mg/L (2025 data). Scale builds slowly at this level; a light white film on kettles and taps is possible, and a softener is rarely needed.
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 | 44 mg/L |
|---|---|
| Utility | Tokushima City Waterworks & Sewerage Bureau |
How Tokushima compares
- Tap water in Tokushima is 12 % softer than the median of the 228 cities we track in Japan (50 mg/L).
- By hardness it ranks 142 of 228 in Japan (1 = hardest); 38 % of these cities have softer water.
- Nearest city with clearly softer water: Miki, 44 km away (34 mg/L).
- Nearest city with clearly harder water: Higashikagawa, 27 km away (64 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 Tokushima
| 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 Tokushima water hard or soft?
It is soft: 44 mg/L as CaCO₃ (2.6 gpg, 2.5 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Tokushima 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 Tokushima water?
2.6 gpg, equal to 2.5 °dH, 4.4 °fH or 44 mg/L calcium carbonate.
What dishwasher salt setting should I use in Tokushima?
For 44 mg/L (2.5 °dH) check your manufacturer's table: level 0–1, usually no salt.
Do I need a water softener in Tokushima?
No. With soft water a softener adds nothing.
Source
Source: 徳島市上下水道局 Tokushima City Waterworks & Sewerage Bureau, tap-water quality results FY2025 (上下水道事業年報 水道水質編) (2025). Method: figure published by the water supplier. 徳島市上下水道局 Tokushima City Waterworks & Sewerage Bureau, tap-water quality results FY2025 (上下水道事業年報 水道水質編) · Outdated figure? Tell us