Ten prefectures have radioactive tap water, according to the Japanese government.

Fukushima, Tochigi,  Gunma,  Saitama, Chiba, Tokyo, Kanagawa, Niigata and Yamanashi prefectures.

Tap water in Tochigi and Gunma revealed radioactive iodine and cesium.

Radioactive iodine alone was found in Saitama, Chiba, Tokyo, Kanagawa, Niigata and Yamanashi prefectures.

It must be noted that several different government agencies are involved with testing for radiation levels. People have been told the radiation levels exceed safety levels, but officials think that at this point there is not health threat.