Cesium from tap water in 26% of all the prefectures

Tap water is the most essential element of our daily life. You need it for cooking, shower, and drinking. You need it even when you make your baby food.

However, in 26% of all the prefectures in Japan, they detected cesium from tap water.


According to Monitoring information of environmental radioactivity level of  Ministry of Education, Culture, Sports, Science and Technology, [Link] they measured cesium 134/137 from tap water of 12 prefectures.  They conducted measurement in 46 prefectures. (Only Miyagi applies different lowest detectable amount, which can’t be compare.)

The measurement was from April to June, 2012.


The prefectures are

  • Iwate
  • Yamagata
  • Fukushima
  • Ibaraki
  • Tochigi
  • Gunma
  • Saitama
  • Chiba
  • Tokyo
  • Kanagawa
  • Niigata
  • Nagano


The highest reading was 0.0112 Bq/Kg (Cs-134/137) in Ibaraki. It was higher than Fukushima for some reason. It was 0.0049 Bq/Kg in Tokyo.

Full report is below.


Cesium from tap water in 26% of the prefectures


Cesium from tap water in 26% of the prefectures 2





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This website updates the latest news about the Fukushima nuclear plant and also archives the past news from 2011. Because it's always updated and added live, articles, categories and the tags are not necessarily fitted in the latest format.
I am the writer of this website. About page remains in 2014. This is because my memory about 311 was clearer than now, 2023, and I think it can have a historical value. Now I'm living in Romania with 3 cats as an independent data scientist.
Actually, nothing has progressed in the plant since 2011. We still don't even know what is going on inside. They must keep cooling the crippled reactors by water, but additionally groundwater keeps flowing into the reactor buildings from the broken parts. This is why highly contaminated water is always produced more than it can circulate. Tepco is planning to officially discharge this water to the Pacific but Tritium is still remaining in it. They dilute this with seawater so that it is legally safe, but scientifically the same amount of radioactive tritium is contained. They say it is safe to discharge, but none of them have drunk it.