Water hardness in Kadoma
40 mg/L soft
Tap water in Kadoma is soft: 40 mg/L (2.3 gpg · 2.2 °dH · 4 °fH).
Source: Kadoma City Waterworks (門真市水道), via Osaka Prefecture 「大阪府の水道の現況」 FY2024 water quality tables (2024) · data checked 2026-10-21
Kadoma 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 Kadoma is not confirmed here. The reported figure is a single value of 40.0 mg/L CaCO₃ (2024 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 | 40 mg/L |
|---|---|
| Utility | Kadoma City Waterworks (門真市水道) |
How Kadoma compares
- Tap water in Kadoma is 20 % softer than the median of the 228 cities we track in Japan (50 mg/L).
- By hardness it ranks 170 of 228 in Japan (1 = hardest); 25 % of these cities have softer water.
- In Osaka it is number 33 of 42 cities; the regional median is 42 mg/L.
- Nearest city with clearly softer water: Tondabayashi, 27 km away (17 mg/L).
- Nearest city with clearly harder water: Settsu, 5 km away (63 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 Kadoma
| 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 Kadoma water hard or soft?
It is soft: 40 mg/L as CaCO₃ (2.3 gpg, 2.2 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Kadoma 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 Kadoma water?
2.3 gpg, equal to 2.2 °dH, 4 °fH or 40 mg/L calcium carbonate.
What dishwasher salt setting should I use in Kadoma?
For 40 mg/L (2.2 °dH) check your manufacturer's table: level 0–1, usually no salt.
Do I need a water softener in Kadoma?
No. With soft water a softener adds nothing.
Source
Source: Kadoma City Waterworks (門真市水道), via Osaka Prefecture 「大阪府の水道の現況」 FY2024 water quality tables (2024). Method: figure published by the water supplier. Kadoma City Waterworks (門真市水道), via Osaka Prefecture 「大阪府の水道の現況」 FY2024 water quality tables · Outdated figure? Tell us