Water hardness in Sakai
39 mg/L soft
Tap water in Sakai is soft: 39 mg/L (2.3 gpg · 2.2 °dH · 3.9 °fH).
Source: 堺市上下水道局 Sakai City Waterworks & Sewerage Bureau, tap-water quality results FY2024 (水質検査結果報告書) (2024) · data checked 2026-10-21
Range across supply zones: 34–43 mg/L.
Sakai 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 Sakai is not confirmed here. The reported figure is 39.4 mg/L CaCO₃ (range 34.0 to 43.4 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 | 39 mg/L |
|---|---|
| Utility | Sakai City Waterworks & Sewerage Bureau |
How Sakai compares
- Tap water in Sakai is 22 % softer than the median of the 228 cities we track in Japan (50 mg/L).
- By hardness it ranks 174 of 228 in Japan (1 = hardest); 24 % of these cities have softer water.
- In Osaka it is number 37 of 42 cities; the regional median is 42 mg/L.
- Nearest city with clearly softer water: Tondabayashi, 15 km away (17 mg/L).
- Nearest city with clearly harder water: Fujiidera, 12 km away (66 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 Sakai
| 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 Sakai water hard or soft?
It is soft: 39 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 Sakai 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 Sakai water?
2.3 gpg, equal to 2.2 °dH, 3.9 °fH or 39 mg/L calcium carbonate.
What dishwasher salt setting should I use in Sakai?
For 39 mg/L (2.2 °dH) check your manufacturer's table: level 0–1, usually no salt.
Do I need a water softener in Sakai?
No. With soft water a softener adds nothing.
Source
Source: 堺市上下水道局 Sakai City Waterworks & Sewerage Bureau, tap-water quality results FY2024 (水質検査結果報告書) (2024). Method: figure published by the water supplier. 堺市上下水道局 Sakai City Waterworks & Sewerage Bureau, tap-water quality results FY2024 (水質検査結果報告書) · Outdated figure? Tell us