A study of Rn-222 concentrations in the water distribution system of T
ucson, Arizona, revealed levels of 60 to 1260 pCi/L in domestic waters
. These measurements are comparable to levels of between 80 and 1400 p
Ci/l for Rn-222 found in ground water samples in the North-Central Tuc
son basin (Kalin et al., 1994). Estimated loss of Rn-222 due to radioa
ctive decay during travel from the well head to the home ranges from 8
to 50 percent.