This International Standard describes the conditions for the determination of 14C activity concentration in samples of environmental water or of 14C containing water using liquid scintillation counting.The scintillation phenomenon results from interaction of ionizing radiation with solvents and compounds exhibiting fluorescence (scintillators). Both solvents and scintillators constitute the scintillation cocktail. The scintillation mixture is achieved by adding the scintillation cocktail to the test sample in order to obtain a homogeneous mixture.Some examples of methods with sample pretreatment are described in Annexes C and D.NOTE 1 The method is applicab