ISO 13164-4:2015描述了通过萃取和液体闪烁计数测定非盐水中氡222（222Rn）活度浓度的试验方法。氡-222活度浓度可使用现有仪器通过本试验方法测量，对于10毫升的试验样品和1小时的测量时间而言，至少高于0.5 Bq l-1。本试验方法可成功用于饮用水样品，实验室有责任确保本试验方法对未经试验基质的水样的有效性。附录A给出了满足饮用水监测所需检测限值的必要计数条件。

ISO 13164-4:2015 describes a test method for the determination of radon-222 (222Rn) activity concentration in non-saline waters by extraction and liquid scintillation counting. The radon-222 activity concentrations, which can be measured by this test method utilizing currently available instruments, are at least above 0,5 Bq l−1 for a 10 ml test sample and a measuring time of 1 h. This test method can be used successfully with drinking water samples and it is the responsibility of the laboratory to ensure the validity of this test method for water samples of untested matrices. Annex A gives indication on the necessary counting conditions to meet the required detection limits for drinking water monitoring.