Water hardness in Toyonaka
44 mg/L soft
Tap water in Toyonaka is soft: 44 mg/L (2.6 gpg · 2.5 °dH · 4.4 °fH).
Source: Toyonaka City Waterworks, monthly water quality results 2025-08 to 2026-07 (水質基準項目等検査結果) (2026-07) · data checked 2026-10-21
Range across supply zones: 36–69 mg/L.
Toyonaka is supplied by its own waterworks, which in Osaka Prefecture typically buy Yodo River water, the outflow of Lake Biwa, from the Osaka Water Supply Authority and sometimes add local wells; the exact mix for Toyonaka is not confirmed here. The reported figure is 44.0 mg/L CaCO₃ (range 36.4 to 68.9 mg/L, 2026 data). Limescale is mild here, appearing slowly on kettles and taps, so occasional descaling is enough.
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 | Toyonaka City Waterworks and Sewerage Bureau (豊中市上下水道局) |
How Toyonaka compares
- Tap water in Toyonaka is 12 % softer than the median of the 228 cities we track in Japan (50 mg/L).
- By hardness it ranks 143 of 228 in Japan (1 = hardest); 37 % of these cities have softer water.
- In Osaka it is number 17 of 42 cities; the regional median is 42 mg/L.
- Nearest city with clearly softer water: Tadaoka, 33 km away (34 mg/L).
- Nearest city with clearly harder water: Minoo, 5 km away (58 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 Toyonaka
| 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 Toyonaka 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 Toyonaka 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 Toyonaka 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 Toyonaka?
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 Toyonaka?
No. With soft water a softener adds nothing.
Source
Source: Toyonaka City Waterworks, monthly water quality results 2025-08 to 2026-07 (水質基準項目等検査結果) (2026-07). Method: figure published by the water supplier. Toyonaka City Waterworks, monthly water quality results 2025-08 to 2026-07 (水質基準項目等検査結果) · Outdated figure? Tell us