Reply #39: Here is link with links to what they checked and results.

[uppityperson]

http://www.nuc.berkeley.edu/UCBAirSampling

For instance
http://www.nuc.berkeley.edu/node/2278
Tapwater
The following are results for tap water samples taken from a sink in Etcheverry Hall, UC Berkeley campus. The only isotope we have detected besides background is I-131, at low significance: 0.024 ± 0.014 Becquerels per liter. This level is much lower than our rain water measurements by a factor of approximately 500, and lower than our milk measurement by a factor of 3.

In the table below the plots, we are providing two numbers for each of the isotopes. The first is a standard concentration unit of Becquerel per liter (Bq/L) which describes the number of particles decaying over the period of one second. For the general public, we have converted this number to an exposure dose per liter of water consumed. The number in parentheses is the number of liters of water that one would need to consume to equal the radiation exposure of a single round trip flight from San Francisco to Washington D.C. (0.05 mSv). For more information on how this equivalent dose is calculated, the details are here: How Effective Dose is Calculated

The tap water measurements are done with the same setup as the Rainwater Collection Experiment.

I-131
Sample Date Bq/L (liters**)
Estimated Minimum Detectable Activity (MDA) 0.018
3/29/2011 7:54 0.024 ± 0.014 (110,000)
3/30/2011 11:50 less than MDA