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
From a certificate analyzed in 2007.
This list uses the wording the Ministry of the Environment replaced in 2014, so it may not match a current certificate. Items marked † were removed from the official list of contraindications then, or include a condition that was. If you have a health condition, ask a doctor before bathing.
- Acute illness (especially when fever is present)
- Active tuberculosis
- Malignant tumor
- Severe heart disease
- Respiratory failure
- Renal failure
- Bleeding disorders
- Severe anemia
- Any illness in an actively progressing stage
- Pregnancy (especially the early and late stages) (dropped from the official list in 2014)
- Fully contraindicated, whether or not an illness is present
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⁺87.2mgP25 national
- Calciumsettling and calming; can leave a white mineral bloomCa²⁺8.7mgP23 national
- Potassiumminor; matters for drinking limitsK⁺0.20mgP1 national
- Magnesiummild; a laxative if you drink itMg²⁺0.20mgP14 national
- Aluminumshows up in acidic volcanic waterAl³⁺0.10mgP56 national
- Iron (II)rusts brown in air; iron for anemia when drinkableFe²⁺0.10mgP29 national
- AmmoniumNH₄⁺0.10mgP23 national
- Manganesetrace; companion to iron springsMn²⁺< —mg
- Bicarbonate"soda" — softens skin, leaves it smoothHCO₃⁻187mgP57 national
- Chloridetable-salt anion — coats the skin and holds heat inCl⁻24.2mgP17 national
- Fluoridetrace; drinking limits applyF⁻3.0mgP65 national
- Sulfate"gypsum / Glauber's salt" — vessels and wound healingSO₄²⁻0.50mgP5 national
- Hydrogen phosphateHPO₄²⁻0.10mgP34 national
- Hydrogen sulfidesulfur character — antibacterialHS⁻0.10mgP25 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
From a certificate analyzed in 2007.
This list uses the wording the Ministry of the Environment replaced in 2014, so it may not match a current certificate.
- Neuralgia
- 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.