Groundwater treatment as a source of indoor radon

• This work presents the preliminary results of a 222Rn study conducted during a period of one and a half years in a new Viimsi Parish water treatment plant.
• It was quantitatively established that both open filter columns of water treatment plant act as a source of indoor air 222Rn.
• 222Rn indoor measurements under the normal operation conditions revealed that activity concentrations in the filter hall of water treatment plant fall between 600 and 700 Bq/m3.

New Viimsi Parish water treatment plant (Northern Estonia) was investigated in order to determine whether the open filter columns serve as a source of 222Rn generation in the treatment process and whether they influence indoor air 222Rn activity concentrations. 222Rn measurements of indoor 222Rn were performed at different locations of the treatment plant; water samples from incoming raw water, from all the purification stages, consumers water and solid filter material from two filtration stages were analyzed.