Bandaiko
Analysis UnverifiedBandaiko is one of Kusatsu Onsen's defining springs, deeply entwined with the town's long tradition of yutomi (water-mixing) and therapeutic bathing. Its name is said to trace back to the area's mining heritage, giving it a rugged, authentic character. It is the ideal spring for those seeking a genuine curative experience—especially anyone looking to reset troubled skin or shake off deep-seated fatigue.
The bar length shows how abundant each component is compared to thresholds that make it "distinctive" (therapeutic spring standards, beauty spring criteria, etc.).
Strong astringent action that tightens skin. A key component of acidic springs, suited to oily or acne-prone skin.
Mild antibacterial action keeps the skin clean. Trace transdermal absorption supports tooth and bone health.
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.
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.
Given the extremely low pH of 1.75, start with short sessions of 3–5 minutes and monitor your skin's reaction before gradually extending to 10–15 minutes. After bathing, pat dry with a towel rather than rinsing—though those with sensitive skin are advised to rinse off with warm water. Limit bathing to once or twice daily at first, and only increase frequency after the third day to avoid 'yu-atari' (thermal fatigue), following the classic Kusatsu bathing tradition.
Bandaiko spring boasts one of Japan's most intensely acidic profiles—pH 1.75 at 94.6°C—with dissolved solids totaling 3.18 g/kg, dominated by sulfate (840 mg/kg) and chloride (707 mg/kg). Its powerful bactericidal action has earned recognition for atopic dermatitis, psoriasis, and pyoderma, while also being indicated for peripheral circulatory disorders, chills, and depressive states. It is especially recommended for those with chronic joint or muscle pain and those seeking to fundamentally restore skin health.
Those with sensitive skin or mucous membranes, and elderly individuals with dry skin conditions should avoid this spring due to its spring-specific contraindications. People with serious heart, lung, or kidney disease, active bleeding, or illness in the acute phase should also refrain from bathing.
※ See the analysis data below for detailed contraindications
ANALYSIS DATAView all analysis fields ▼
Source Info
- Source name
- 万代鉱
- Spring type
- 酸性水素・硫酸塩・塩化物温泉（低張性酸性高温泉）
- Source temperature
- 94.6℃
- pH
- 1.75
- Flow type
- 掘削自噴
- Osmotic pressure
- 低張性
Analysis Document
- Analysis date
- 2023-08-04
- Analyst organization
- 一般社団法人 群馬県薬剤師会（環境衛生試験センター）
- Registration No.
- 群馬薬第2号
Cations
- Hydrogen ion H⁺
- 19.9 mg/kg
- Sodium ion Na⁺
- 138 mg/kg
- Potassium ion K⁺
- 64.4 mg/kg
- Ammonium ion NH₄⁺
- 0.40 mg/kg
- Magnesium ion Mg²⁺
- 76.0 mg/kg
- Calcium ion Ca²⁺
- 114 mg/kg
- Aluminum ion Al³⁺
- 43.2 mg/kg
- Manganese ion Mn²⁺
- 3.6 mg/kg
- Iron(II) ion Fe²⁺
- 3.0 mg/kg
- Lead ion Pb²⁺
- 0.08 mg/kg
- Copper ion Cu²⁺
- 0.00 mg/kg
- Total cations
- 0.46 mg/kg
Anions
- Fluoride ion F⁻
- 25.1 mg/kg
- Chloride ion Cl⁻
- 708 mg/kg
- Sulfate ion SO₄²⁻
- 840 mg/kg
- Bromide ion Br⁻
- 4.5 mg/kg
- Hydrogen sulfate HSO₄⁻
- 565 mg/kg
- Total anions
- 2.1 mg/kg
Undissociated Components
- Sulfuric acid H₂SO₄
- 28.5 mg/kg
- Metasilicic acid H₂SiO₃
- 528 mg/kg
- Metaboric acid HBO₂
- 21.4 mg/kg
- Total undissociated
- 0.58 mg/kg
Dissolved Gas
- Free carbon dioxide CO₂
- 26.4 mg/kg
- Free hydrogen sulfide H₂S
- 0.00 mg/kg
- Total dissolved gas
- 0.03 mg/kg
Totals
- Total dissolved substances
- 3.2 mg/kg
- Component total
- 3.2 mg/kg
- Evaporation residue
- 2.5 mg/kg
Usage
- Heating
- No
- Dilution
- Yes（Water dilution for temperature adjustment. As the source spring temperature is extremely high at 94.5-96°C, water dilution is performed to lower the temperature to levels suitable for drinking. While some facilities specify "no water dilution or heating" on official websites, water dilution is typically included during heat exchange in the distribution system.）
- Recycle / Filter
- No
- Additives
- No
- Disinfection
- No
Indications & Contraindications
- Bathing indications
- Chronic pain or stiffness in muscles and joints (rheumatoid arthritis, osteoarthritis, lower back pain, neuralgia, frozen shoulder, contusion, sprain and other chronic conditions), muscle stiffness due to motor paralysis, gastrointestinal dysfunction (gastric discomfort, intestinal gas accumulation, etc.), high blood pressure (mild), dyslipidemia (mild), mild asthma or emphysema, hemorrhoids pain, autonomic instability, stress-related symptoms (sleep disorders, etc.), convalescence, fatigue recovery, health promotion. By spring quality: Atopic dermatitis, psoriasis vulgaris, impaired glucose tolerance (diabetes), pyogenic skin infection, cuts and grazes, peripheral circulatory failure, poor circulation, depression, xeroderma
- Contraindications
- General contraindications: Active disease state (especially with fever), active tuberculosis, advanced malignant tumors or cases with marked physical debility such as severe anemia, severe heart or lung disease that causes shortness of breath with minimal exertion, severe kidney disease with edema, gastrointestinal hemorrhage, visible bleeding, acute exacerbation of chronic disease. By spring quality: Persons with sensitive skin or mucous membranes, xeroderma in elderly persons
Drinking
- Drinkability
- Not drinkable