Kowakudani Onsen
Analysis VerifiedKowakidani Onsen, once known as 'Kojigoku' (Small Hell) due to its fumaroles, was renamed in 1873 following Emperor Meiji's visit. This mixed spring, combining multiple sources developed since the late Meiji era, stands as one of Hakone's most iconic hot springs. Its waters envelop the skin in a comforting salt veil, delivering restorative warmth deep into the body's core. This mellow, historically rich spring is highly recommended for those seeking deep relaxation and a profound reset from daily life.
The bar length shows how abundant each component is compared to thresholds that make it "distinctive" (therapeutic spring standards, beauty spring criteria, etc.).
A natural moisturizer also used in skincare lotions. Forms a thin veil on the skin to reduce moisture loss after bathing.
A trace component with gentle antibacterial and anti-inflammatory action.
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 water is diluted due to the high source temperature, but avoid long soaks and stay hydrated. As a sodium-chloride spring, it warms the body deeply, and its restorative warmth lingers, making you less prone to post-bath chills. Resting after your bath is recommended.
This is a skin-friendly sodium-chloride spring with a mild alkalinity of pH 7.9. Its rich salt content forms a light veil on the skin, providing lasting restorative warmth. Furthermore, it contains 168 mg/kg of metasilicic acid, a known skin-beautifying component, which may lead to moist, silky skin after bathing.
Individuals undergoing medical treatment, who are pregnant, or have sensitive skin or mucous membranes should consult a doctor before bathing. Avoid bathing if you have acute illnesses, active tuberculosis, or severe heart disease.
※ See the analysis data below for detailed contraindications
ANALYSIS DATAView all analysis fields ▼
Source Info
- Source name
- Kowakudani Onsen
- Spring type
- Sodium Chloride Hot Spring
- Old spring type name
- 単純温泉
- Source temperature
- 60℃
- pH
- 7.9
- Osmotic pressure
- 低張性
Analysis Document
- Analysis date
- 2016-04-12
- Valid until
- 2024-04-11
- Analyst organization
- 神奈川県温泉地学研究所
- Registration No.
- 登録第1号
Cations
- Lithium ion Li⁺
- 0.02 mg/kg
- Sodium ion Na⁺
- 109 mg/kg
- Potassium ion K⁺
- 5.8 mg/kg
- Magnesium ion Mg²⁺
- 0.31 mg/kg
- Calcium ion Ca²⁺
- 7.4 mg/kg
- Aluminum ion Al³⁺
- 0.01 mg/kg
- Manganese ion Mn²⁺
- 0.08 mg/kg
- Iron(II) ion Fe²⁺
- 0.02 mg/kg
- Zinc ion Zn²⁺
- 0.00 mg/kg
- Strontium ion Sr²⁺
- 0.03 mg/kg
- Copper ion Cu²⁺
- 0.00 mg/kg
- Total cations
- 0.12 mg/kg
Anions
- Fluoride ion F⁻
- 0.09 mg/kg
- Chloride ion Cl⁻
- 30.9 mg/kg
- Sulfate ion SO₄²⁻
- 48.3 mg/kg
- Bicarbonate ion HCO₃⁻
- 215 mg/kg
- Carbonate ion CO₃²⁻
- 1.3 mg/kg
- Bromide ion Br⁻
- 0.05 mg/kg
- Nitrate ion NO₃⁻
- 0.00 mg/kg
- Metasilicate ion SiO₃²⁻
- 2.6 mg/kg
- Metaborate ion BO₂⁻
- 0.15 mg/kg
- Total anions
- 0.30 mg/kg
Undissociated Components
- Metasilicic acid H₂SiO₃
- 168 mg/kg
- Metaboric acid HBO₂
- 3.0 mg/kg
- Total undissociated
- 0.17 mg/kg
Dissolved Gas
- Free carbon dioxide CO₂
- 4.5 mg/kg
- Free hydrogen sulfide H₂S
- 0.00 mg/kg
- Total dissolved gas
- 0.00 mg/kg
Totals
- Total dissolved substances
- 0.59 mg/kg
- Component total
- 0.60 mg/kg
- Evaporation residue
- 0.48 mg/kg
Usage
- Heating
- Yes（The water is heated for hygiene purposes as it is stored in a holding tank.）
- Dilution
- Yes（Water is added because the source temperature is high.）
- Recycle / Filter
- No
- Additives
- No
- Disinfection
- No
Indications & Contraindications
- Bathing indications
- Chronic pain or stiffness in muscles and joints (chronic phase of rheumatoid arthritis, osteoarthritis, low back pain, neuralgia, frozen shoulder, bruises, sprains), Muscle stiffness due to motor paralysis, Poor circulation, Gastrointestinal dysfunction (stomach heaviness, intestinal gas), High blood pressure (mild), Impaired glucose tolerance (diabetes), Dyslipidemia, Mild asthma or emphysema, Hemorrhoids, Autonomic instability, Symptoms associated with stress (insomnia, depression), Post-illness recovery, Fatigue recovery, Health promotion, Cuts and grazes, Xeroderma
- Contraindications
- Active stages of illness (especially with fever), Active tuberculosis, Advanced malignant tumors or severe anemia with significant physical debilitation, Severe heart or lung disease causing shortness of breath with slight movement, Severe kidney disease with swelling, Gastrointestinal bleeding, Visible bleeding, Acute exacerbation of chronic illness
Drinking
- Drinkability
- Not drinkable
