During heavy rains two week ago, high levels of radiation were detected in rainwater on the University of California Berkeley campus. According to the Bay Citizen, the radiation levels were 181 times higher than what is considered safe for drinking water. Radiation was also detected in California milk samples, according to the LA Times.
UC Berkeley’s Department of Nuclear Engineering measured Iodine-131 levels of 20.1 Becquerels per liter on the roof of Etcheverry Hall. The federal maximum for drinking water is 0.111 Becquerels per liter. Their report can be read here. The good news is that I-131 decays rapidly, so it is unlikely that anyone received a prolonged exposure.
Today the UCB Dept of Nuclear Engineering published data showing no detectable radiation in tap water. On March 31, they detected I-131 in tap water at 0.024 Becquerels per liter, well below the safety limit. Elevated levels of I-131 were detected in milk (with a “Best if Used by” date of 4/4) that were six times the 0.111Becquerel per liter limit. However, one would have to consume 3,800 liters of this tainted milk to receive the same radiation one would receive from flying across the country.