Tap water hardness in Tokyo

We have published hardness data for 53 cities in Tokyo. The median is 62 mg/L; the hardest water is in Musashino (82 mg/L), the softest in Okutama (34 mg/L).

0 % of these cities have hard or very hard water (over 120 mg/L).

Japanese waterworks report hardness (硬度) in mg/L CaCO₃; the standard is 300 mg/L and the target 10–100 mg/L.

Cities in Tokyo, hardest first

All cities in Japan →