Water profile

銀泉（ラジウム泉）Ginsen (Radium spring)

ラRadon

A simple radon spring of Arima's silver-water (ginsen) tradition. The wellhead is cold at 18.2 °C, neutral pH 7.35, colorless and transparent, tasteless and odorless. Radon registers at a high 1,900 Bq/kg (about 140 mache units), placing it firmly in the radon-hormesis family; the source is reheated for bathing.

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

On the certificate:NeuralgiaMuscle painJoint painFrozen shoulderMotor paralysisJoint stiffnessBruisesSprains

Recovery

Warmth and buoyancy lower stress markers and improve sleep; habitual bathing is linked to lower rates of depression.

fatigue, stress

On the certificate:ConvalescenceFatigue recoveryGeneral health improvement

Take care

Contraindications

Acute illness (especially when fever is present)
Active tuberculosis
Malignant tumor
Severe heart disease
Pregnancy
Any illness in an actively progressing stage
Contraindicated for hot baths (42°C and above): arteriosclerosis, hypertension

Measured at the source

7.35

Neutral

Source temperature

18.2°C

Cold mineral

Tonicity

Hypotonic

Flow rate

83L/min

Typical

Radon

1900Bq/kg

High

On the certificate

Chronic digestive disorders
Hemorrhoids
Cold sensitivity
When bathing above 42°C: arteriosclerosis, hypertension
Gout
Chronic digestive disorders
Chronic cholecystitis
Gallstones
Diabetes

Evidence

有明2号（玉泉・赤湯）Ariake No. 2 (Tamasen / Akayu)

鉄Iron-bearing

Among Japan's hottest natural sources at 94.8 °C, this is Arima's celebrated kinsen (gold-water) lineage — an iron-bearing sodium chloride strong-salt spring, hypertonic and neutral. Dissolved solids exceed 56 g/kg, far above ocean salinity, and the iron oxidizes on contact with air to leave the brown sediment that gives the bath its akayu (red water) name. Strongly salty with a pronounced metallic edge, and the salt layer it leaves on the skin is thick and warming.

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

On the certificate:NeuralgiaMuscle painJoint painFrozen shoulderMotor paralysisJoint stiffnessBruisesSprains

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, netto 熱の湯).

cold sensitivity

On the certificate: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

On the certificate:Burns