Water drawn from the No. 1 distribution station in Dogo Yunomachi, Matsuyama — a gentle simple thermal spring, lightly mineralized and easy on the body. Its alkalinity gives the slippery beauty-water feel, reinforced by a generous helping of metasilicic acid that leaves a thin silica film for noticeably smoother skin. The posted analysis lists autonomic nervous system instability, insomnia and depressed mood among its indications, alongside the usual chronic aches and fatigue recovery. The bath is disinfected with a chlorine-based agent to meet Matsuyama's public bathhouse hygiene standard; no dilution, reheating or recirculation is declared.
Good for
Aches & joints
Warmth eases stiffness and raises the pain threshold. Radon and sulfate springs show the strongest evidence for joint and muscle pain.
stiff shoulders
Smooth skin
Bicarbonate and alkalinity gently lift dead keratin while silica hydrates, leaving skin smooth. This is the basis of the beautifying-water (bijin-no-yu 美人の湯) reputation.
dry, rough skin
Recovery
Warmth and buoyancy lower stress markers and improve sleep; habitual bathing is linked to lower rates of depression.
fatigue, stress
Take care
- Active stage of any illness (especially with fever)
- Active tuberculosis
- Advanced malignant tumor, severe anemia, or other marked physical debilitation
- Severe heart or lung disease causing breathlessness on slight exertion
- Severe kidney disease accompanied by edema
- Gastrointestinal bleeding
- Visible bleeding
- Acute exacerbation of a chronic illness
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.
- Sodiumsalt's cation — pairs with chloride to make the water saltyNa⁺71.2mgP20 national93%
- Calciumsettling and calming; can leave a white mineral bloomCa²⁺4.3mgP16 national6%
- PotassiumK⁺0.70mgP9 national0.6%
- LithiumLi⁺0.10mgP27 national0.3%
- MagnesiumMg²⁺0.10mgP11 national0.3%
- Aluminumshows up in acidic volcanic waterAl³⁺< —mg
- BariumBa²⁺< —mg
- Iron (II)rusts brown in air; iron for anemia when drinkableFe²⁺< —mg
- Iron (III)Fe³⁺< —mg
- Manganesetrace; companion to iron springsMn²⁺< —mg
- AmmoniumNH₄⁺< —mg
- StrontiumSr²⁺< —mg
- ZincZn²⁺< —mg
- Bicarbonate"soda" — softens skin, leaves it smoothHCO₃⁻74.7mgP37 national37%
- Chloridetable-salt anion — coats the skin and holds heat inCl⁻28.9mgP22 national25%
- Fluoridetrace; drinking limits applyF⁻12.5mgP96 national20%
- Sulfate"gypsum / Glauber's salt" — vessels and wound healingSO₄²⁻19.6mgP34 national12%
- Carbonatestrongly alkaline; slippery feelCO₃²⁻5.5mgP36 national5%
- HydroxideOH⁻0.20mgP65 national0.3%
- Bromidetrace, sea-originBr⁻< —mg
- Iodideyellows in air; helps blood lipidsI⁻< —mg
- NitrateNO₃⁻< —mg
- Thiosulfateoxidized sulfurS₂O₃²⁻< —mg
- Metasilicic acidmetasilicic acid — a natural moisturizer for silky skinH₂SiO₃52.3mgP33 national
- Metaboric acidmetaboric acid — mildly antibacterialHBO₂4.6mgP36 national
- Free carbon dioxidefizz — widens blood vessels (strong above 1000 mg/kg)CO₂0.10mgP12 national
- ArsenicAs0.0050mgP20 national
- CadmiumCd< —mg
- ChromiumCr< —mg
- CopperCu< —mg
- Mercurytoxic trace — part of the drinking-safety checkHg< —mg
- LeadPb< —mg
Measured at the source
On the certificate
- Chronic muscle or joint pain and stiffness (rheumatoid arthritis, osteoarthritis, lower back pain, neuralgia, frozen shoulder, bruises, sprains — chronic phase)
- Cold sensitivity
- Peripheral circulation disorders
- Reduced gastrointestinal function (heaviness, bloating)
- Mild hypertension
- Impaired glucose tolerance (diabetes)
- Mild hypercholesterolemia
- Mild asthma or emphysema
- Hemorrhoid pain
- Stress-related symptoms (sleep disorders, depressed mood)
Evidence
- Maeda M. 温泉の医学的効果とその科学的根拠. J. Hot Spring Science 70:197–207, 2021.
- Naito Y et al. A Hot-Spring Water Improves Inflammatory Conditions in an Atopic Dermatitis Model. Biomedicines 13(11):2707, 2025.
- Donaubauer AJ et al. Serial radon spa therapy on pain in musculoskeletal disorders. Frontiers in Immunology, 2024.
- Verhagen AP et al. Balneotherapy for rheumatoid arthritis. Cochrane Database of Systematic Reviews CD000518, 2015.
- Li H et al. Bicarbonate Ionized Water Bathing Enhances Natural Killer Cell Activity. Scientific Reports 14:51851, 2024.
- Takeda M et al. Hot spring bathing practices have a positive effect on mental health in Japan. Heliyon 9(9):e19631, 2023.