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Iron ion: Main Effects & Top 5

Published May 5, 2026·1min read

Iron(II) ion (Fe²⁺) is the marker of iron-rich springs. The water turns yellow-brown to red-brown when exposed to air, offering strong heat retention.

National maximum
22.0 mg/kg
@
Noboribetsu Onsen Manseikaku
Table of Contents
  1. What is Iron ion?
  2. Main Effects
  3. Iron ion Top 5 Hot Springs

What is Iron ion?

Iron(II) ion (Fe²⁺) is the marker of iron-rich springs. The water turns yellow-brown to red-brown when exposed to air, offering strong heat retention.

Main Effects

  • Strong heat retention
  • Indicated for iron-deficiency anemia (drinking)
  • Characteristic reddish-brown cloudy water

Iron ion Top 5 Hot Springs

Top 5 hot springs registered on this site with the highest content.

* Top 5 among onsen analysis records registered in this app

References

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