Onsen OniOnsen Oni

Public bath No.9 O-yu

九番湯 渋大湯きゅうばんゆ しぶおおゆ

Public Bathhouse
Yudanaka–Shibu Onsen-kyoShibu Onsen
Chubu·Nagano
0269-33-2921shibuonsen.net

Day Use

Yes

Bathing & Water

Outdoor BathNo

Open-air outdoor bath

Indoor BathYes

Enclosed indoor bathing area

SaunaNo

Dry heat sauna room

Cold BathNo

Cold water plunge bath, typically used after sauna

OnsenYes

Uses natural hot spring water

Capabilities

Private BathNo

Private bath available for day-use visitors or hotel guests to reserve

Room OnsenNo

Private onsen bath in guest rooms, for overnight guests only

Mixed BathingNo

Shared bathing area for all genders

渋大湯（大湯と渋温泉総合源泉の混合泉）

Shibu O-yu (blend of O-yu and the Shibu Onsen combined source)

Operated by · 渋温泉旅館組合

Mixed source

Sampled at bath inlet
硫
Sulfate
+ Chloride
Classification

Sodium-Calcium Sulfate spring

A blended source — Shibu O-yu, combining O-yu with the Shibu Onsen combined source — classified as a sodium-calcium sulfate-chloride spring. Sulfate gives the water a quiet body with a salty edge layered in, and it is moderately mineralized with noticeable presence. Weakly acidic, it carries a metallic iron taste with a faint saltiness. With 159 mg/kg of metasilicic acid, it leaves a thin silica film for noticeably smoother skin.

pH
5.70
Weakly acidic
Source temperature
60.2°C
Hot
Tonicity
1.25g/kg
Hypotonic
Flow rate
54.1L/min
Typical
Free CO₂
22mg/kg
Low
Color
almost colorless and transparent, with an iron and faintly salty taste
Taste
metallic iron taste with a faint saltiness
Highlights
  • High silica

Analyzed Nov 24, 2015·一般社団法人 上田薬剤師会 検査センター

Programs

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SM
Sergey M
2 years ago

Public bath No.9 O-yu, Shibu onsen 9th and last onsen of Shibu. The most developed of the nine — the changing room is even quite warm in winter. The bath is divided into two sections, the water is cloudy. I went first thing in the morning and the water was nuclear hot — I had to dilute it with cold water for about 10 minutes to actually get into the first section. The second section behind the partition remained brutally hot. Among the Shibu onsens — recommended. It's a bit more modern than the rest, has more space, and there's a temperature challenge. Yet it still retains the old-school feel.