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Kawarayu

蔵王温泉 川原湯共同浴場ざおうおんせん かわらゆきょうどうよくじょう

Public Bathhouse
Tohoku·Yamagata

Day Use

Yes
06:00–22:00
¥300

Adults ¥300, children ¥100. Payment via coin box at entrance.

Bathing & Water

Natural onsen water

Uses natural hot spring water

Outdoor BathNo

Open-air outdoor bath

Indoor BathYes

Enclosed indoor bathing area

Bathing Arrangements

Mixed BathingNo

Shared bathing area for all genders

Policies & Services

DiningNo

Restaurant or dining open to visitors (not just hotel meal plans)

WashingNo

Shower, wash stations, soap and shampoo provided

TowelsNo

Towels available to rent or borrow

川原湯共同浴場源泉

Kawarayu Communal Bathhouse Spring

Operated by · 川原湯共同浴場

Acidic
+ 含硫黄泉 · Sulfate · Chloride
Color
colorless and clear
Taste
astringent
Odor
hydrogen sulfide

Hydrogen-Aluminum Sulfate-Chloride spring

pH 1.9AcidicHot source · 42°CUltra-acidicHigh silicaSulfur-rich
Composition fingerprint2.3 g/kg dissolved · Hypotonic
H⁺36
Al³⁺25
Mg²⁺17
SO₄²⁻61
Cl⁻25
HSO413
CationsAnions
Hydrogen H⁺
makes the water acidic — sharp and bactericidal.
Sulfate SO₄²⁻
"gypsum / Glauber's salt" — vessels and wound healing.
Known good for
  • Skin conditionsatopic skin, eczema
  • Circulationtired legs
  • Aches & jointsstiff shoulders
  • Sensitive-skin cautionbroken or dry skin

The source feeding the Kawarayu communal bathhouse in Zao Onsen, Yamagata: a strongly acidic, sulfur-bearing aluminium-sulfate-chloride water. It is acidic enough to prickle on contact — the sharply acidic style associated with stubborn skin conditions — and carries the unmistakable rotten-egg note of H₂S at the spout, with an astringent tang if tasted. Moderately mineralized with noticeable body, it also holds a generous 195 mg/kg of metasilicic acid, which tempers the bite with a smoothing silica film. The posted composition notice records the water reaching the bath at the same temperature as the source, and the certificate's sample was drawn in the bathhouse tub itself rather than at a wellhead.

Sampled at community bath·Analyzed Feb 7, 2020·株式会社丹野·Cert no. O1900013

Explore the water

About

One of three public baths at Zao Onsen (蔵王温泉, Zao Onsen), this one has a feature the others don't: the spring water rises directly through a wooden-slat floor beneath you (ashimoto-yushutsu, 足下湧出). The water is a sharp, acidic sulfur spring run as kakenagashi (かけ流し, free-flowing), with well water blended in to bring the temperature down from the hot source. No showers, no soap allowed, no amenities at all. You rinse with a bucket and soak. The building sits over a hot-spring stream, and outside you can see the water flowing underneath. Unmanned facility with a coin box at the entrance.

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Sergey M
7 months ago· edited

759. Kawarayu, Zao Onsen, Yamagata ★ An old-school onsen for ¥300. The listed hours are 06:00 to 22:00. No staff, no shower. Indoor bath. The boards on the bottom are not fully fixed and move around a bit. The water is clear and acidic with a bluish tint, and there is lime on the bottom. Temperature: 44. Breathing inside is fine, but it is cold in January. A solid old-school onsen. If you like a harsh atmosphere, keep that in mind. 09.01.2026

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Last updated July 30, 2026