ISO 13165-2:2014 specifies the determination of radium-226 (226Ra) activity concentration in all types of water by emanometry. The method specified is suitable for the determination of the soluble, suspended, and total 226Ra activity concentration in all types of water with soluble 226Ra activity concentrations greater than 0,02 Bq l-1. In water containing high activity concentrations of 228Th, interference from 220Rn decay products can lead to overestimation of measured levels.