Radioactivity in drinking water supplies in Western Australia

Radiochemical analysis was carried out on 52 drinking water samples taken from public outlets in the southwest of Western Australia. All samples were analysed for Ra-226, Ra-228 and Pb-210. Twenty five of the samples were also analysed for Po-210, and 23 were analysed for U-234 and U-238. Ra-228 was found in 45 samples and the activity ranged from <4.000 to 296.1mBqL-1. Ra-226 was detected in all 52 samples and the activity ranged from 3.200 to 151.1mBqL-1. Po-210 was detected in 24 samples and the activity ranged from 0.000 to 114.2mBqL-1. These data were used to compute the annual radiation dose that persons of different age groups and also for pregnant and lactating females would receive from drinking this water. The estimated doses ranged from 0.001 to 2.375mSvy-1 with a mean annual dose of 0.167mSvy-1. The main contributing radionuclides to the annual dose were Ra-228, Po-210 and Ra-226. Of the 52 drinking water samples tested, 94% complied with the current Australian Drinking Water Guidelines, while 10% complied with the World Health Organization's radiological guidelines which many other countries use. It is likely that these results provide an overestimate of the compliance, due to limitations, in the sampling technique and resource constraints on the analysis. Because of the increasing reliance of the Western Australian community on groundwater for domestic and agricultural purposes, it is likely that the radiological content of the drinking water will increase in the future. Therefore there is a need for further monitoring and analysis in order to identify problem areas.