Water profile — Yamada Bessou

山田別荘の湯Yamada Bessou Spring

曹BicarbonateSodium-Magnesium Bicarbonate spring

A sodium-magnesium bicarbonate spring of the jūsō-sen style — mildly alkaline and soft on the skin, moderately mineralized with noticeable body. It sits squarely in Japan's beauty-water family, and a generous 228 mg/kg of metasilicic acid leaves the kind of silica film that makes skin feel noticeably smoother afterwards. The certificate records fine black particles settling out of the sample about five hours after collection, a quiet hint of how much mineral matter the water carries.

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

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

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.

Cationsshare of charge (mval%)

Sodiumsalt's cation — pairs with chloride to make the water saltyNa⁺194mgP50 national59%
Magnesiummild; a laxative if you drink itMg²⁺35.7mgP80 national21%
Calciumsettling and calming; can leave a white mineral bloomCa²⁺43.8mgP55 national15%
Potassiumminor; matters for drinking limitsK⁺16.6mgP56 national3%
LithiumLi⁺1.3mgP85 national1%
Iron (II)Fe²⁺0.20mgP39 national0.1%
ManganeseMn²⁺0.20mgP45 national0.1%

Anionsshare of charge (mval%)

Bicarbonate"soda" — softens skin, leaves it smoothHCO₃⁻657mgP82 national74%
Chloridetable-salt anion — coats the skin and holds heat inCl⁻91.0mgP38 national18%
Sulfate"gypsum / Glauber's salt" — vessels and wound healingSO₄²⁻60.2mgP44 national9%

Non-dissociatedmeasured by mass

Metasilicic acidmetasilicic acid — a natural moisturizer for silky skinH₂SiO₃228mgP91 national
Metaboric acidmetaboric acid — mildly antibacterialHBO₂6.2mgP44 national
Metaarsenious acidHAsO₂0.20mgP70 national

Dissolved gasesmeasured by mass

Free carbon dioxidefizz — widens blood vessels (strong above 1000 mg/kg)CO₂197mgP88 national

Measured at the source

8.05

Weakly alkaline

Source temperature

55.3°C

Hot

Tonicity

1.33g/kg

Hypotonic

Free CO₂

197mg/kg

Low

Evidence

露天の湯Roten no Yu (Open-Air Bath Spring)

曹BicarbonateSodium Bicarbonate-Chloride spring · +Chloride

Roten no Yu — the name means 'open-air bath water' — is a sodium bicarbonate spring, listed on the certificate under an older name meaning salt-bearing soda water. The jūsō-sen character comes with a chloride sub-type that leaves a faint salty edge, and at a mildly alkaline pH the water feels soft on the skin, placing it in Japan's beauty-water family. Metasilicic acid runs to 233 mg/kg, leaving a thin silica film that makes skin feel noticeably smoother, over a moderately mineralized body.

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

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

Warming

Salt forms a film on the skin that slows heat loss, so the warmth lingers long after the bath (the classic heat-keeping water, nettō 熱の湯).

cold sensitivity

Cuts

Mineral-rich chloride, sulfate and sulfur waters have a long-recorded soothing effect on minor cuts and slow-healing skin.

minor wounds