本文件规定了通过液体闪烁计数（LSC）直接在试样上或在化学分离后测量所有类型水样中14C活性浓度的方法。 该方法适用于供水/饮用水、雨水、地表水和地下水、海水以及冷却水、工业用水、生活和工业废水的测试样品。 检测限取决于样品体积、使用的仪器、样品计数时间、背景计数率、检测效率和化学回收率。本文中描述的方法使用当前可用的液体闪烁计数器和适当的技术条件，检测限低至1 Bq∙l−1，低于世界卫生组织安全饮用水标准（100 Bq·l）- 1). 14C活性浓度可测量高达106 Bq∙l-1，无任何样品稀释。 用户有责任确保本测试方法对测试水样的有效性。

This document specifies a method for the measurement of 14C activity concentration in all types of water samples by liquid scintillation counting (LSC) either directly on the test sample or following a chemical separation. The method is applicable to test samples of supply/drinking water, rainwater, surface and ground water, marine water, as well as cooling water, industrial water, domestic, and industrial wastewater. The detection limit depends on the sample volume, the instrument used, the sample counting time, the background count rate, the detection efficiency and the chemical recovery. The method described in this document, using currently available liquid scintillation counters and suitable technical conditions, has a detection limit as low as 1 Bq∙l−1, which is lower than the WHO criteria for safe consumption of drinking water (100 Bq·l-1). 14C activity concentrations can be measured up to 106 Bq∙l-1 without any sample dilution. It is the user’s responsibility to ensure the validity of this test method for the water samples tested.