Zao Onsen
Japan · Asia
The water
74 mg/LModerate
Source: GEX MeGreen (Japan Water Works Association statistics) · Published figure. Hardness counts dissolved calcium and magnesium in the water; it is the number your hair meets in the shower.
What moderate water does to hair
Neither the easy rinse of soft water nor the coating of hard: routines travel well here. The only adjustment worth making is a clarifying wash every so often to lift the light build-up.
The washing routine for Zao Onsen
Wash as usual, and make every eighth wash or so a detox (chelating) one. That single habit covers moderate water; the rest of your products and timing can stay exactly as they are.
Climate, from recent records (Open-Meteo, ERA5 2015-2024): August is the warmest month, averaging 24°C by day, and humidity peaks in July at about 87% on average. In the humid months, frizz is the main event; anti-humidity styling matters more than wash frequency.
Local note: Served by Yamagata City supply through its dedicated Zao Onsen plant; a second Zao plant (Zao Hotta) reads 113 mg/L while city lowland plants read 21-27 mg/L.
Plugs and power for your tools
Sockets: Type A and B. Supply: 100 V, 50 Hz.
Japan runs at 100 V, lower than almost anywhere else: a dryer wound for 230 V only will barely warm up here, and one bought here can burn out on 230 V back home. Check the label for dual voltage (100-240 V) before you plug in.
Plug, voltage and frequency: IEC World Plugs and national standards.
Plan Zao Onsen properly
The trip planner turns this water profile into a wash plan for your hair type, a chosen kit and a packing list, month by month.