湯SimpleSodium Bicarbonate-Chloride spring
A simple thermal spring rising in the Yamada district of Kita ward, Kobe. Neutral and hypotonic, it emerges at 27.3 °C as a cold-mineral spring, so it is heated before bathing. At the source the water is colorless and transparent yet carries a faint metallic taste and a faint hydrogen sulfide note, with around 30 mg/kg of metasilicic acid giving it a gentle, soft feel on the skin.
Good for
Recovery
Warmth and buoyancy lower stress markers and improve sleep; habitual bathing is linked to lower rates of depression.
fatigue, stress
Full composition
The bar is each ion's share of charge (mval%) within its group; over 20% names the spring. Gases, silica and trace metals are measured by mass only.
Cationsshare of charge (mval%)
- Sodiumsalt's cation — pairs with chloride to make the water saltyNa⁺122mgP35 national82%
- Calciumsettling and calming; can leave a white mineral bloomCa²⁺19.1mgP38 national15%
- Magnesiummild; a laxative if you drink itMg²⁺1.4mgP29 national2%
- PotassiumK⁺1.1mgP14 national0.5%
- LithiumLi⁺0.20mgP40 national0.5%
- Iron (II)Fe²⁺0.70mgP58 national0.3%
- StrontiumSr²⁺0.30mgP55 national0.2%
- Aluminumshows up in acidic volcanic waterAl³⁺< —mg
- BariumBa²⁺< —mg
- Iron (III)Fe³⁺< —mg
- Manganesetrace; companion to iron springsMn²⁺< —mg
- AmmoniumNH₄⁺< —mg
Anionsshare of charge (mval%)
- Bicarbonate"soda" — softens skin, leaves it smoothHCO₃⁻297mgP65 national74%
- Chloridetable-salt anion — coats the skin and holds heat inCl⁻46.5mgP27 national20%
- Fluoridetrace; drinking limits applyF⁻6.2mgP82 national5%
- SulfateSO₄²⁻1.1mgP8 national0.3%
- CarbonateCO₃²⁻0.30mgP14 national0.1%
- Bromidetrace, sea-originBr⁻< —mg
- Hydrogen sulfidesulfur character — antibacterialHS⁻< —mg
- Iodideyellows in air; helps blood lipidsI⁻< —mg
- SS²⁻< —mg
- Thiosulfateoxidized sulfurS₂O₃²⁻< —mg
Non-dissociatedmeasured by mass
- Metasilicic acidmetasilicic acid — a natural moisturizer for silky skinH₂SiO₃30.4mgP13 national
- Metaboric acidmetaboric acid — mildly antibacterialHBO₂10.4mgP57 national
- Metaarsenious acidHAsO₂0.10mgP56 national
Dissolved gasesmeasured by mass
- Free carbon dioxidefizz — widens blood vessels (strong above 1000 mg/kg)CO₂41.3mgP65 national
- Free hydrogen sulfide"egg" smell — opens vessels, antibacterialH₂S< —mg
Trace metalsmeasured by mass
- ArsenicAs0.10mgP64 national
- CopperCu< —mg
- Mercurytoxic trace — part of the drinking-safety checkHg< —mg
- LeadPb< —mg
Measured at the source
Source temperature
27.3°C
Low temp.
Tonicity
0.54g/kg
Hypotonic
Free CO₂
41mg/kg
Low
Free H₂S
0.10mg/kg
Low