Water hardness in Shimamoto
83 mg/L moderately hard
Tap water in Shimamoto is moderately hard: 83 mg/L (4.8 gpg · 4.6 °dH · 8.3 °fH).
Source: Shimamoto Town Waterworks (島本町水道), via Osaka Prefecture 「大阪府の水道の現況」 FY2024 water quality tables (2024) · data checked 2026-10-21
Shimamoto 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 Shimamoto is not confirmed here. The utility publishes one value, 83.0 mg/L CaCO₃ (2024 data). Scale is noticeable on kettles, heaters and tap fittings, so descale more often; a softening cartridge is optional.
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 | 83 mg/L |
|---|---|
| Utility | Shimamoto Town Waterworks (島本町水道) |
How Shimamoto compares
- Tap water in Shimamoto is 65 % harder than the median of the 228 cities we track in Japan (50 mg/L).
- By hardness it ranks 7 of 228 in Japan (1 = hardest); 97 % of these cities have softer water.
- In Osaka it is number 4 of 42 cities; the regional median is 42 mg/L.
- Nearest city with clearly softer water: Takatsuki, 7 km away (42 mg/L).
Ranking of the hardest and softest water in Japan →
What it means at home
- Visible kettle scale every few weeks; vinegar or citric acid is enough.
- Water heater and washing machine: some long-term scale; a scale inhibitor slows it.
- Dishwasher: medium salt setting.
- Softener optional; pays off mainly with a gas boiler or tankless heater.
How much salt will you use for softening?
Optional. A scale inhibitor or a small softener protects the heater; soap savings are modest.
Descale a coffee machine or kettle about every 3 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Shimamoto
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 5 °dH |
| AEG / Electrolux | 2 |
| Beko | 1st |
| Hoover | S1 |
| LG | H1 |
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 Shimamoto water hard or soft?
It is moderately hard: 83 mg/L as CaCO₃ (4.8 gpg, 4.6 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Shimamoto 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 Shimamoto water?
4.8 gpg, equal to 4.6 °dH, 8.3 °fH or 83 mg/L calcium carbonate.
What dishwasher salt setting should I use in Shimamoto?
For 83 mg/L (4.6 °dH) check your manufacturer's table: level 2–3.
Do I need a water softener in Shimamoto?
Not essential; a scale inhibitor protects the heater cheaply.
Source
Source: Shimamoto Town Waterworks (島本町水道), via Osaka Prefecture 「大阪府の水道の現況」 FY2024 water quality tables (2024). Method: figure published by the water supplier. Shimamoto Town Waterworks (島本町水道), via Osaka Prefecture 「大阪府の水道の現況」 FY2024 water quality tables · Outdated figure? Tell us