Water hardness in Suita
41 mg/L soft
Tap water in Suita is soft: 41 mg/L (2.4 gpg · 2.3 °dH · 4.1 °fH).
Source: Suita City Waterworks Department, annual water quality report FY2024 (水質試験年次報告書 令和6年度 第52集 改訂版) (2024) · data checked 2026-10-21
Range across supply zones: 32–48 mg/L.
Suita runs plants on Yodo River water and groundwater and buys about 60% of its supply from the Osaka Water Supply Authority. Hardness is reported at 41.0 mg/L CaCO₃, ranging from 32.0 to 48.0 mg/L (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 | 41 mg/L |
|---|---|
| Utility | Suita City Waterworks Department (吹田市水道部) |
How Suita compares
- Tap water in Suita is 18 % softer than the median of the 228 cities we track in Japan (50 mg/L).
- By hardness it ranks 163 of 228 in Japan (1 = hardest); 27 % of these cities have softer water.
- In Osaka it is number 29 of 42 cities; the regional median is 42 mg/L.
- Nearest city with clearly softer water: Tondabayashi, 30 km away (17 mg/L).
- Nearest city with clearly harder water: Settsu, 7 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 Suita
| 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 Suita water hard or soft?
It is soft: 41 mg/L as CaCO₃ (2.4 gpg, 2.3 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Suita 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 Suita water?
2.4 gpg, equal to 2.3 °dH, 4.1 °fH or 41 mg/L calcium carbonate.
What dishwasher salt setting should I use in Suita?
For 41 mg/L (2.3 °dH) check your manufacturer's table: level 0–1, usually no salt.
Do I need a water softener in Suita?
No. With soft water a softener adds nothing.
Source
Source: Suita City Waterworks Department, annual water quality report FY2024 (水質試験年次報告書 令和6年度 第52集 改訂版) (2024). Method: figure published by the water supplier. Suita City Waterworks Department, annual water quality report FY2024 (水質試験年次報告書 令和6年度 第52集 改訂版) · Outdated figure? Tell us