A simple weakly-radioactive spring rising in Arima, carrying enough radon (137 Bq/kg) to fall within the radon-spring tradition. The water is colorless and transparent but develops a yellow-brown sediment if left to stand for a long time. As a cold-mineral source of 22.0 °C, it is reheated for bathing and disinfected with a chlorine-based agent. The posted indications cover neuralgia, muscle pain, joint pain and similar chronic complaints.
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
Recovery
Warmth and buoyancy lower stress markers and improve sleep; habitual bathing is linked to lower rates of depression.
fatigue, stress
Take care
- Active phase of illness (especially when fever is present)
- Active tuberculosis
- Advanced malignant tumors, severe anemia, or other markedly debilitating conditions
- Severe cardiopulmonary disease causing breathlessness on slight exertion
- Severe kidney disease accompanied by edema
- Gastrointestinal bleeding
- When there is 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⁺210mgP53 national73%
- Calciumsettling and calming; can leave a white mineral bloomCa²⁺44.9mgP56 national18%
- Potassiumminor; matters for drinking limitsK⁺21.9mgP66 national5%
- Magnesiummild; a laxative if you drink itMg²⁺—mg2%
- Iron (II)rusts brown in air; iron for anemia when drinkableFe²⁺4.1mgP78 national1%
- LithiumLi⁺0.80mgP70 national1.0%
- ManganeseMn²⁺0.20mgP45 national0.1%
- Aluminumshows up in acidic volcanic waterAl³⁺0.09mgP37 national
- Chloridetable-salt anion — coats the skin and holds heat inCl⁻296mgP63 national71%
- Bicarbonate"soda" — softens skin, leaves it smoothHCO₃⁻66.1mgP34 national12%
- Fluoridetrace; drinking limits applyF⁻4.6mgP77 national2%
- SulfateSO₄²⁻0.58mgP5 national0.1%
- Metasilicic acidmetasilicic acid — a natural moisturizer for silky skinH₂SiO₃67.2mgP42 national
- Metaboric acidmetaboric acid — mildly antibacterialHBO₂7.5mgP48 national
- Free carbon dioxidefizz — widens blood vessels (strong above 1000 mg/kg)CO₂175mgP87 national
Measured at the source
On the certificate
- Chronic pain or stiffness of muscles or joints (chronic phase of rheumatoid arthritis, osteoarthritis, lower back pain, neuralgia, frozen shoulder, bruises, sprains, etc.)
- Sensitivity to cold
- Peripheral circulatory disorders
- Reduced gastrointestinal function (feeling of fullness in the stomach, gas in the intestines, etc.)
- Mild hypertension
- Impaired glucose tolerance (diabetes mellitus)
- Mild hypercholesterolemia
- Mild asthma or emphysema
- Hemorrhoidal pain
- Various stress-related symptoms (sleep disorders, depressive states, etc.)
- Hyperuricemia (gout), rheumatoid arthritis, ankylosing spondylitis, etc.
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.
- 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.
- Takeda M et al. Hot spring bathing practices have a positive effect on mental health in Japan. Heliyon 9(9):e19631, 2023.