Are "bicarbonate spring" and "baking-soda spring" the same thing?

Yes. The official scientific name is "bicarbonate spring," but it is often called "baking-soda spring" (重曹泉) because the dominant anion (HCO₃⁻) is the same compound found in household baking soda.

Does the beauty benefit apply to everyone?

Yes — the skin-smoothing effect of bicarbonate applies regardless of gender. Anyone with rough or dull skin can benefit.

How does it help with diabetes when drunk?

Bicarbonate spring water is officially indicated for impaired glucose tolerance (diabetes) when taken as a drink. It is a supportive measure only — always follow your doctor's guidance.

Bicarbonate Springs: "Beauty Waters" for Smooth, Glowing Skin

Table of Contents

What is a Bicarbonate Spring?
Indications for Bathing
Indications for Drinking
How to Bathe in a Bicarbonate Spring

Bicarbonate spring onsen — Photo: Partner facility

What is a Bicarbonate Spring?

A bicarbonate spring has hydrogen carbonate ions (HCO₃⁻) as its dominant anion — the same compound as household baking soda, earning it the nickname "baking-soda spring" (重曹泉).

When you bathe, the bicarbonate softens the stratum corneum and washes away dead skin cells and sebum like a gentle soap, leaving your skin noticeably smoother. This skin-refining quality has earned it the title "the beauty waters" (美人の湯) across Japan.

Indications for Bathing

Cuts
Peripheral circulatory failure
Excessive sensitivity to cold
Xeroderma (dry skin)

Indications for Drinking

Gastroduodenal ulcerations
Reflux esophagitis
Impaired glucose tolerance (diabetes)
Hyperuricemia (gout)

How to Bathe in a Bicarbonate Spring

Bicarbonate strips oils efficiently, so moisturize after bathing if your skin feels dry.
Pat skin dry without rinsing to keep the beneficial components on your body.
For beauty purposes, two 10–15 minute baths work better than one long soak — over-bathing can strip too much keratin.

Recommended Onsen Sequence

Bicarbonate spring → sulphur spring → chloride spring: the bicarbonate removes old keratin, the sulphur boosts circulation, and the chloride seals in moisture — the classic beauty onsen tour.

Related Onsen Facilities

Bicarbonate Spring

Awaiting analysis

TRY IT NOW

Find This Onsen on the Map

Search on Map →Filter & Explore

Search on Map →

References

環境省「あんしん・あんぜんな温泉利用のいろは」（平成31年3月発行、監修: 一般社団法人日本温泉気候物理医学会）
環境省「温泉地の多言語化促進マニュアル」(2021年版)
鉱泉分析法指針（平成26年改訂）

SPRING TYPEMay 5, 2026· 1min read

Simple Springs (Tanjun Onsen): Gentle Waters for Everyone

Simple springs have dissolved components below 1,000 mg/kg and a source temperature of 25°C or above. Mild and non-irritating, they are safe for all ages. Alkaline simple springs (pH 8.5+) are famous for leaving skin silky smooth.

SPRING TYPEMay 5, 2026· 1min read

Sulphate Springs: "The Healing Waters" for Wounds, Skin & Digestion

Sulphate springs (SO₄²⁻ as the main anion) are called "the healing waters" for their anti-inflammatory, skin-moisturizing properties. Indicated for bathing (cuts, cold sensitivity, dry skin, depression) and drinking (biliary dysfunction, dyslipidemia, constipation).

SPRING TYPEMay 5, 2026· 2min read

Chloride Springs: Benefits, Indications & Recommended Onsen

Chloride springs (Cl⁻ as the main anion) are known as "the hot-retaining waters" because the salt coating on your skin keeps body heat from escaping after bathing. Excellent for cold sensitivity and dry skin.

MINERALMay 5, 2026· 2min read

Metasilicic Acid: The "Beauty Spring" Standard Mineral & Top 5 Onsen

Metasilicic acid (H₂SiO₃) is a natural moisturizer also found in skincare lotions. Hot springs containing more than 50mg/kg are called "beauty springs" — leaving skin hydrated long after bathing. This is one of the therapeutic spring criteria in Japan's Mineral Spring Analysis Guideline (Table 1-1).

MINERALMay 5, 2026· 1min read

Bicarbonate ion: Main Effects & Top 5

Bicarbonate ion (HCO₃⁻) — the same ingredient as baking soda — gently removes old skin cells and sebum for silky-smooth skin. Known as the "beauty spring" (美人の湯).

SAFETYMay 6, 2026· 1min read

Drinking Hot Spring Water (Insatsu) | What It Is, Benefits & Safety Rules

Insatsu — drinking hot spring water directly — has a long history in Japan and Europe. Certain spring types are recognised to support digestive and metabolic health, but the practice is strictly regulated and must be done at authorised facilities only.