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Simple Springs (Tanjun Onsen): Gentle Waters for Everyone

Published May 5, 2026·1min read

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.

Simple Springs (Tanjun Onsen): Gentle Waters for Everyone
Analysis records
10 records
Prefectures
7 prefectures
Table of Contents
  1. What is a Simple Spring?
  2. Indications for Bathing
  3. How to Bathe in a Simple Spring
Simple spring onsen
Tokachigawa Onsen
北海道 Makubetsu, Nakagawa District
Photo: Partner facility

What is a Simple Spring?

A simple spring contains less than 1,000 mg of dissolved components per kilogram of spring water, at a source temperature of 25°C or above. The name "simple" does not mean weak — it means no single component dominates, creating a well-balanced, gentle spring.

Alkaline simple springs with pH 8.5 or above soften the skin's stratum corneum, leaving you with silky-smooth skin after bathing — one reason they are so popular with beauty-conscious bathers.

Indications for Bathing

  • Autonomic instability
  • Insomnia
  • Depression

How to Bathe in a Simple Spring

  1. Mild stimulation means you can soak for up to 20 minutes. Half-body bathing (seated in shallow water) reduces strain on the heart.
  2. Alkaline simple springs strip oils easily — apply moisturizer after bathing if your skin feels dry.
  3. A pre-sleep soak in lukewarm water is especially effective for insomnia relief.

Recommended Onsen Sequence

Start with a simple spring → move to a bicarbonate spring → finish with a sulphate or chloride spring. This sequence minimizes skin stress while maximizing beauty and moisturizing benefits (Japan Ministry of the Environment multilingual manual).

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