Yumoto No. 29 & 46 Goko-sen
Analysis VerifiedHakone-Yumoto Onsen, said to have opened in the Nara period, boasts the oldest history in Hakone. This Yumoto No. 29 & 46 Goko-sen is a blend of multiple sources from this historic spa town. It is used in public bathhouses along the old Tokaido road, having soothed weary travelers for centuries.
The bar length shows how abundant each component is compared to thresholds that make it "distinctive" (therapeutic spring standards, beauty spring criteria, etc.).
A trace component with gentle antibacterial and anti-inflammatory action.
- Alkaline (pH)pH 8.7
- Feel
- Feels slippery and silky on the skin.
- Said to
- Said to remove old skin cells and excess sebum.
- Note
- Skin can dry out afterwards—moisturize after bathing.
- Metasilicic acid52.7 mg/kg
- Feel
- Your skin may feel smoother.
- Said to
- 50 mg/kg or more is said to mark a “skin-beautifying spring”; it is also used in skincare.
- Note
- The “skin-beautifying” label is a common rule of thumb, not a legal standard.
- Source temperature45.8℃
- Feel
- The source is 42°C or hotter; the bath may be on the hot side.
- Said to
- Heat is said to boost circulation and warm the body.
- Note
- Older people and those with high blood pressure or heart conditions should avoid baths of 42°C or more. Keep soaks short.
Effects are general descriptions based on the Ministry of the Environment’s indications by spring type, not a guarantee.
Scores are calculated from mineral analysis data based on the Mineral Spring Analysis Guidelines (Ministry of Environment, Japan). They are unrelated to facility atmosphere or service quality.
▸Note
The temperature, pH and component values shown here are based on the hot spring analysis (source). Actual values in the bath may differ depending on heating, dilution, recycling and filtration. Please check current usage status at the facility.
The pH 8.7 alkaline water can soften skin, but long soaks may cause dryness; moisturize after bathing. The spring is warm at 45.8°C, so acclimate your body with "kake-yu" (scooping and pouring water on yourself) and start with shorter dips.
With a high alkalinity of pH 8.7, this spring is ideal for achieving silky skin, often called "bihada-no-yu" (beautiful skin water) for its ability to gently exfoliate. Containing 52.7 mg/kg of metasilicic acid, it supports skin moisture, making it perfect for deep relaxation and rejuvenation.
Avoid bathing if you have general contraindications like acute illness, active tuberculosis, or severe heart disease. Pregnant individuals, especially in early and late stages, should be cautious. Sudden entry into hot water may cause dizziness.
※ See the analysis data below for detailed contraindications
ANALYSIS DATAView all analysis fields ▼
Source Info
- Source name
- Yumoto No. 29 & 46 Goko-sen
- Spring type
- Alkaline Simple Hot Spring
- Old spring type name
- 単純温泉
- Source temperature
- 45.8℃
- pH
- 8.7
- Osmotic pressure
- 低張性
Analysis Document
- Analysis date
- 2012-11-01
- Analyst organization
- 神奈川県温泉地学研究所
- Registration No.
- 神奈川県知事登録第1号
Cations
- Lithium ion Li⁺
- 0.01 mg/kg
- Sodium ion Na⁺
- 95.5 mg/kg
- Potassium ion K⁺
- 0.87 mg/kg
- Ammonium ion NH₄⁺
- 0.00 mg/kg
- Magnesium ion Mg²⁺
- 0.03 mg/kg
- Calcium ion Ca²⁺
- 6.0 mg/kg
- Aluminum ion Al³⁺
- 0.03 mg/kg
- Manganese ion Mn²⁺
- 0.01 mg/kg
- Iron(II) ion Fe²⁺
- 0.00 mg/kg
- Zinc ion Zn²⁺
- 0.00 mg/kg
- Lead ion Pb²⁺
- 0.00 mg/kg
- Strontium ion Sr²⁺
- 0.00 mg/kg
- Copper ion Cu²⁺
- 0.00 mg/kg
- Cadmium ion Cd²⁺
- 0.00 mg/kg
- Total cations
- 102 mg/kg
Anions
- Fluoride ion F⁻
- 0.22 mg/kg
- Chloride ion Cl⁻
- 80.3 mg/kg
- Sulfate ion SO₄²⁻
- 45.2 mg/kg
- Bicarbonate ion HCO₃⁻
- 71.5 mg/kg
- Carbonate ion CO₃²⁻
- 2.8 mg/kg
- Bromide ion Br⁻
- 0.16 mg/kg
- Nitrate ion NO₃⁻
- 1.7 mg/kg
- Hydrogen metasilicate HSiO₃⁻
- 5.2 mg/kg
- Metaborate ion BO₂⁻
- 1.0 mg/kg
- Total anions
- 208 mg/kg
Undissociated Components
- Metasilicic acid H₂SiO₃
- 52.7 mg/kg
- Metaboric acid HBO₂
- 3.3 mg/kg
- Total undissociated
- 56.0 mg/kg
Dissolved Gas
- Free carbon dioxide CO₂
- 0.22 mg/kg
- Total dissolved gas
- 0.22 mg/kg
Totals
- Total dissolved substances
- 366 mg/kg
- Component total
- 367 mg/kg
- Evaporation residue
- 311 mg/kg
Usage
- Usage status
- Unknown
Indications & Contraindications
- Bathing indications
- Autonomic instability, Insomnia, Depression
- General indications
- High blood pressure (mild), Rheumatoid arthritis, Chronic pain or stiffness in muscles and joints, Muscle stiffness due to motor paralysis, Gastrointestinal dysfunction
- Contraindications
- Acute illness (especially with fever), Active tuberculosis, Malignant tumors, Severe heart disease, Respiratory failure, Renal failure, Bleeding disorders, Severe anemia, Any actively progressing illness, Pregnancy (especially early and late stages)
Drinking
- Drinkability
- Not drinkable
