Gero Onsen (Koda Pump Station)
Analysis UnverifiedGero Onsen counts among Japan's three famous springs, and legend holds that when its waters once vanished, a white heron alighted on the Masuda riverbank to reveal a new gush sent by the healing Buddha Yakushi. The Gero Onsen Koda pump station source gathers several centrally managed wells and sends them to inns across the Koda district. Its pH 9.4 alkaline water glides softly over the skin and lingers as a light, refreshed feeling afterward, soothing travelers who seek gentle rest.
The bar length shows how abundant each component is compared to thresholds that make it "distinctive" (therapeutic spring standards, beauty spring criteria, etc.).
Mild antibacterial action keeps the skin clean. Trace transdermal absorption supports tooth and bone health.
- Alkaline (pH)pH 9.4
- 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 acid66.7 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 temperature56℃
- 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.
With a slippery pH 9.4 alkaline touch, go light on soap and let the water glide over the skin. As a mild simple spring, it suits an unhurried 10 to 15 minute soak at a moderate temperature.
With a pH of 9.4 and 66.7 mg/kg of metasilicic acid, this water is traditionally associated with silky skin, softening the outer layer gently. As a mild simple spring, it may also support deep relaxation on days when work or travel fatigue needs to be eased.
Avoid bathing during acute illness or with serious heart or lung conditions. The source reaches 56°C, so check the bath temperature before entering.
※ See the analysis data below for detailed contraindications
ANALYSIS DATAView all analysis fields ▼
Source Info
- Source name
- Gero Onsen (Koda Pump Station)
- Spring type
- Alkaline Simple Hot Spring
- Source temperature
- 56℃
- pH
- 9.4
Analysis Document
- Analysis date
- 2018-12-03
- Analyst organization
- 一般財団法人 岐阜県公衆衛生検査センター
- Registration No.
- 岐阜県第二号
Cations
- Sodium ion Na⁺
- 104 mg/kg
- Potassium ion K⁺
- 1.4 mg/kg
- Magnesium ion Mg²⁺
- < 0.1 mg/kg
- Calcium ion Ca²⁺
- 2.5 mg/kg
- Aluminum ion Al³⁺
- 0.09 mg/kg
- Manganese ion Mn²⁺
- < 0.001 mg/kg
- Total cations
- 108 mg/kg
Anions
- Fluoride ion F⁻
- 17.0 mg/kg
- Chloride ion Cl⁻
- 81.2 mg/kg
- Hydrogen sulfide ion HS⁻
- 0.30 mg/kg
- Sulfate ion SO₄²⁻
- 11.0 mg/kg
- Bicarbonate ion HCO₃⁻
- 38.7 mg/kg
- Carbonate ion CO₃²⁻
- 25.4 mg/kg
- Nitrate ion NO₃⁻
- < 0.05 mg/kg
- Arsenite ion AsO₂⁻
- 0.20 mg/kg
- Metaborate ion BO₂⁻
- 5.4 mg/kg
- Total anions
- 179 mg/kg
Undissociated Components
- Metasilicic acid H₂SiO₃
- 66.7 mg/kg
- Total undissociated
- 66.7 mg/kg
Dissolved Gas
- Free carbon dioxide CO₂
- < 4 mg/kg
- Free hydrogen sulfide H₂S
- < 0.1 mg/kg
Totals
- Total dissolved substances
- 354 mg/kg
- Component total
- 354 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
