Public Bath No.1 Ichiban yu Hatsu-yu

Day Use

Yes

06:00–22:00

if you have a key when staying at the ryokan

¥0

if you have a key and are staying at the ryokan

Bathing & Water

Natural onsen water

Uses natural hot spring water

Outdoor BathNo

Open-air outdoor bath

Indoor BathYes

Enclosed indoor bathing area

SaunaNo

Sauna room of any kind

Cold BathNo

Cold water plunge bath, typically used after sauna

Bathing Arrangements

Private BathNo

A private bath you can reserve for yourself or your group

Mixed BathingNo

Shared bathing area for all genders

Policies & Services

WashingNo

Shower, wash stations, soap and shampoo provided

渋温泉総合源泉

Shibu Onsen Combined Source

Mixed source

硫

Sulfate

+ Chloride

Color: faintly yellow and clear
Taste: a faint metallic iron taste
Odor: odorless

Sodium-Calcium Sulfate-Chloride spring

pH 4.6Weakly acidicHot source · 65°CHigh silica

Composition fingerprint1.2 g/kg dissolved · Hypotonic

Na⁺55

Ca²⁺34

SO₄²⁻53

Cl⁻45

◀ CationsAnions ▶

Sodium Na⁺: salt's cation — pairs with chloride to make the water salty.
Sulfate SO₄²⁻: "gypsum / Glauber's salt" — vessels and wound healing.

Known good for

Aches & jointsstiff shoulders
Circulationtired legs
Warmingcold sensitivity

A sodium- and calcium-led sulfate-chloride spring, with the quiet body of a sulfate water and a salty edge behind it. It comes out of the ground at 65.0 °C, among Japan's hottest natural sources, and is weakly acidic, so the water carries only a faint tang on the skin. At the wellhead it is faintly yellow and clear, with a light iron taste and no odor. Metasilicic acid at 151.4 mg/kg leaves the kind of thin silica film that makes skin feel noticeably smoother afterwards. The certificate records it as a combined source blending Shibu Onsen's Hira-no-yu, Yakushi-no-yu and Tonbi-no-yu.

Sampled at wellhead·Analyzed Jun 10, 2016·一般社団法人上田薬剤師会検査センター·Cert no. 中28-5(No.430)

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