The radon activity concentration and toxic elements have been assessed in drinking and
irrigated water samples collected from different locations of Sungai Petani, Kedah,
Malaysia. The water samples were collected from wells, streams and taps. A calibrated
alpha spectrometer RAD-7 (Model 2890) and Atomic Absorption Spectrometers (Perkin
eElmer, Model A Analyst 200, Shimadzu, Model AA-700) were used to estimate radon activity
concentration and toxic elements, respectively. Maximum average value of radon
concentration among the various types of water sources was found 14.7 ± 1.44 Bq/l in well
water used for drinking and irrigation and minimum was found 5.37 ± 0.58 Bq/l in tap
water used for drinking. Contribution of radon in drinking water to indoor air and age
dependent associated annual effective doses were calculated from the measured radon
concentration and were found less than lower limit of recommended action level. The
activity concentrations of Ni > Pb > Cd > As > Cr were found higher for streams water as
compared to wells and tap water. Values of radon concentration in well water were found
higher than EPA recommended level and lower than WHO action level while the annual
effective doses and level of toxic elements in water reported in this study were found lower
than recommended level.