UCB Tap Water Sampling
UCB Tap Water Sampling
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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
In the table, MDA stands for Minimum Detectable Activity. This is the lowest level of measurement where we can confidently report results. To find out more about how the MDA is calculated, please visit How we calculate MDA.
The tap water measurements are done with the same setup as the Rainwater Collection Experiment.
| Collection Date | Sample Volume | I131 | I132 | Cs134 | Cs137 | Te132 | Data |
|---|---|---|---|---|---|---|---|
| Liters | Bq/L (liters**) | Bq/L (liters**) | Bq/L (liters**) | Bq/L (liters**) | Bq/L (liters**) | ||
| 03/29/2011 07:54 | 5 |
0.024±0.004 [MDA=0.018] (1.1E+05) |
less than MDA [MDA=0.030] |
less than MDA [MDA=0.017] |
less than MDA [MDA=0.021] |
less than MDA [MDA=0.013] |
data |
| 03/30/2011 11:50 | 5 |
0.029±0.007 [MDA=0.028] (9.2E+04) |
less than MDA [MDA=0.084] |
less than MDA [MDA=0.020] |
0.064±0.012 [MDA=0.051] (4.2E+04) |
less than MDA [MDA=0.020] |
data |
| 03/31/2011 16:00 | 5 |
less than MDA [MDA=0.033] |
less than MDA [MDA=0.114] |
less than MDA [MDA=0.039] |
less than MDA [MDA=0.035] |
less than MDA [MDA=0.031] |
data |
| 04/15/2011 14:00 | 5 |
less than MDA [MDA=0.011] |
less than MDA [MDA=0.066] |
less than MDA [MDA=0.008] |
less than MDA [MDA=0.014] |
less than MDA [MDA=0.014] |
data |
| 04/20/2011 09:40 | 10 |
less than MDA [MDA=0.015] |
less than MDA [MDA=0.088] |
less than MDA [MDA=0.027] |
less than MDA [MDA=0.036] |
less than MDA [MDA=0.022] |
data |
** The number in parentheses is the number of liters of tap 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). To see how we calculate these numbers, please visit our explanation of the equivalent dose calculation.
