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What Is Insatsu (Drinking Onsen Water)? | Culture, Benefits & Safety

Published May 6, 2026·1min read

Insatsu (飲泉) — drinking natural mineral spring water — is an ancient form of spa therapy popular in Europe and practised in select Japanese onsen facilities licensed by prefectural governments.

Table of Contents
  1. History and Culture of Drinking Spring Water
  2. Suitable Spring Types and Expected Benefits

Q & A

Frequently Asked Questions

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Can you drink the water at any onsen?
Drinking spring water is only permitted at designated spots in facilities that hold a prefectural drinking-spring licence. Do not drink water directly from the source.
How much spring water should you drink?
The facility will specify the recommended amount per serving — typically 100–200 ml — taken a few times a day. Never exceed the recommended dose.

History and Culture of Drinking Spring Water

Drinking spa therapy has flourished in Europe since the Middle Ages. Baden-Baden in Germany and Karlovy Vary in the Czech Republic are world-famous drinking spring destinations. In Japan, select facilities such as Kusatsu Onsen and Hakone-Yumoto Onsen are licensed for insatsu.

Suitable Spring Types and Expected Benefits

Spring TypeDrinking Indication
Chloride springImpaired digestive function, chronic constipation
Sulfate springImpaired digestive function, biliary disease
Iron springIron-deficiency anemia
Bicarbonate springGout, hyperuricemia (alkalising urine)
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References

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