Dorogawa Onsen 'Shinsen' is a simple thermal spring classified as hypotonic, weakly alkaline, and low-temperature. The wellhead temperature is a modest 30.7 °C and total dissolved solids come in light at 0.44 g/kg, so the water is gentle on the body and the mildly alkaline pH gives a soft skin feel. The display board doesn't print colour, taste, or odour notes — those sensory details are best gauged at the bath itself.
Good for
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
- 急性疾患(特に熱のある場合)
- Active tuberculosis
- Malignant tumor
- 重い心臓病
- 呼吸不全
- Renal failure
- Bleeding disorders
- Severe anemia
- その他一般に病勢進行中の疾患
- 妊娠中(特に初期と末期)
- 疾病の有無で全面的に禁忌とする
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⁺87.2mgP26 national
- Calciumsettling and calming; can leave a white mineral bloomCa²⁺8.7mgP24 national
- Potassiumminor; matters for drinking limitsK⁺0.20mgP2 national
- Magnesiummild; a laxative if you drink itMg²⁺0.20mgP14 national
- Aluminumshows up in acidic volcanic waterAl³⁺0.10mgP54 national
- Iron (II)rusts brown in air; iron for anemia when drinkableFe²⁺0.10mgP30 national
- AmmoniumNH₄⁺0.10mgP24 national
- Manganesetrace; companion to iron springsMn²⁺< —mg
- Bicarbonate"soda" — softens skin, leaves it smoothHCO₃⁻187mgP56 national
- Chloridetable-salt anion — coats the skin and holds heat inCl⁻24.2mgP19 national
- Fluoridetrace; drinking limits applyF⁻3.0mgP66 national
- Sulfate"gypsum / Glauber's salt" — vessels and wound healingSO₄²⁻0.50mgP5 national
- Hydrogen phosphateHPO₄²⁻0.10mgP34 national
- Hydrogen sulfidesulfur character — antibacterialHS⁻0.10mgP28 national
- Metasilicic acidmetasilicic acid — a natural moisturizer for silky skinH₂SiO₃—mg
- Metaboric acidmetaboric acid — mildly antibacterialHBO₂—mg
- Free carbon dioxidefizz — widens blood vessels (strong above 1000 mg/kg)CO₂< —mg
- Free hydrogen sulfide"egg" smell — opens vessels, antibacterialH₂S< —mg
Measured at the source
On the certificate
- 神経痛
- Muscle pain
- Joint pain
- Frozen shoulder
- Motor paralysis
- Joint stiffness
- Bruises
- Sprains
- Chronic digestive disorders
- Hemorrhoids
- Cold sensitivity
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.
- 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.