武雄温泉第5号源泉Takeo Onsen Spring No. 5
A sodium-led alkaline simple thermal spring, hot at the wellhead (44.5 C). The chemistry leans on bicarbonate with a modest chloride and carbonate edge, giving the slippery, soft feel of Japan's beauty-water family. Mineralization is light at 713 mg/kg, so the water sits gently on the skin rather than coating it.
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
- 病気の活動期(特に熱があるとき)
- Active tuberculosis
- 進行した悪性腫瘍又は高度の貧血など全身衰弱の著しい場合
- 少し動くと息苦しくなるような重い心臓又は肺の病気
- むくみのあるような重い腎臓の病気
- 消化管出血
- 目に見える出血があるとき
- 慢性の病気の急性増悪期
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⁺193mgP48 national
- Calciumsettling and calming; can leave a white mineral bloomCa²⁺2.3mgP9 national
- Potassiumminor; matters for drinking limitsK⁺2.0mgP22 national
- LithiumLi⁺0.40mgP49 national
- Magnesiummild; a laxative if you drink itMg²⁺0.20mgP15 national
- AmmoniumNH₄⁺0.10mgP23 national
- Bicarbonate"soda" — softens skin, leaves it smoothHCO₃⁻360mgP67 national
- Chloridetable-salt anion — coats the skin and holds heat inCl⁻74.8mgP34 national
- Carbonatestrongly alkaline; slippery feelCO₃²⁻16.2mgP61 national
- Fluoridetrace; drinking limits applyF⁻4.7mgP79 national
- Sulfate"gypsum / Glauber's salt" — vessels and wound healingSO₄²⁻1.9mgP11 national
- NitrateNO₃⁻0.40mgP54 national
- Bromidetrace, sea-originBr⁻0.20mgP31 national
- Metasilicic acidmetasilicic acid — a natural moisturizer for silky skinH₂SiO₃48.8mgP29 national
- Metaboric acidmetaboric acid — mildly antibacterialHBO₂9.0mgP50 national
Measured at the source
On the certificate
- 筋肉又は関節の慢性的な痛み又はこわばり(関節リウマチ、変形性関節症、腰痛症、神経痛、五十肩、打撲、捻挫などの慢性期)
- 運動麻痺による筋肉のこわばり
- Cold sensitivity
- Peripheral circulation disorders
- 胃腸機能の低下(胃のもたれ、腸にガスがたまるなど)
- Mild hypertension
- Impaired glucose tolerance (diabetes)
- Mild hypercholesterolemia
- Mild asthma or emphysema
- Hemorrhoid pain
- ストレスによる諸症状
- 病気回復期
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.