ISO 5667-21:2010确立了适用于饮用水取样技术以及食品和饮料产品生产用水取样技术的原则。 ISO 5667-21:2010中给出的指南通常仅限于从市政或类似公共或私人取水、处理或分配系统取水的情况，在这些情况下，事先处理或质量评估已将水归类为适合饮用或饮用工艺目的。具体而言，ISO 5667-21:2010适用于油轮或其他非油轮供应的水- 连续散装是指，在消耗点或输送到管道分配系统之前的任何使用阶段，包括消耗点或输送点，但不连续作为管道分配系统的一部分。ISO 5667-21:2010还适用于飞机、卡车、火车、船舶和其他船舶和车辆上的水分配和散装储存，以及在调查系统缺陷、启动新系统期间可能出现的取样情况，重新启动长时间未使用的系统，或在采样操作人员的安全不受影响的紧急情况下重新启动系统。 ISO 5667-21:2010未提供以下指南:a）水源水取样，例如地下水和蓄水；b） 来自ISO 5667-5所涵盖的连续管道供水的饮用水取样；c） 饮料产品（包括瓶装水）或含有饮用水的食品的取样；d） 饮料自动售货机的抽样。

ISO 5667-21:2010 establishes principles to be applied to the techniques of sampling water provided for drinking and for use in the manufacture of food and beverage products. The guidance given in ISO 5667-21:2010 is generally confined to those circumstances where water is drawn from municipal or similar public or private abstraction, treatment or distribution systems for which prior treatment or quality assessment has resulted in the water being classified as suitable for drinking or potable process purposes. Specifically, ISO 5667-21:2010 is applicable to water that is supplied by tanker or other non-contiguous bulk means, but not contiguously as part of a piped distribution system, during any stage of use up to and including the point of consumption or transfer to a piped distribution system. ISO 5667-21:2010 is also applicable to the distribution and bulk storage of water on aircraft, trucks, trains, ships, and other vessels and vehicles, as well as to sampling situations that can arise during the investigation of system defects, initiation of new systems, re-initiation of systems that have been unused for long periods or emergency situations where the safety of sampling operatives is not compromised. ISO 5667-21:2010 does not provide guidance on: a) the sampling of source water, e.g. groundwater and impoundments; b) the sampling of potable water supplies derived from contiguous piped supplies covered by ISO 5667-5; c) the sampling of beverage products (including bottled waters) or food containing potable water used in its preparation; d) the sampling of drink vending machines.