ISO 17381:2003给出了水分析中现成方法的选择和应用要求的指南。所谓的“即用方法”越来越引起人们的兴趣，因为与标准方法相比，它们可以快速且通常成本低廉地得出分析问题的结果。在一定条件下，这些方法可以应用于水质的常规控制，只要它们给出可靠的结果。 由于现有的即用方法基于不同的分析原理，并且显示出不同的准确度，因此将其分为几组。ISO 17381:2003的目的是建立标准，以确定何时可以使用不同种类的现成方法来分析水样中的不同参数（如饮用水、河水、工艺用水、废水），以及需要采取哪些步骤来证明其适用于特定应用。 现成的方法必须满足特殊的要求，因为它们经常被非专业人员使用- 化学家。ISO 17381:2003列出了这些试验的生产商的要求，涉及安全和环境方面，以及处理和程序说明。还有几项要求涉及对即用方法用户的培训和监督。

ISO 17381:2003 gives guidance on the selection, and requirements for the application, of ready-to-use methods in water analysis. The so-called "ready-to-use methods" are of increasing interest because, compared to standard methods, they allow fast and often inexpensive results for analytical problems. Under certain conditions these methods can be applied in routine control of water quality, provided they give reliable results. As the available ready-to-use methods are based on different analytical principles and also show different degrees of accuracy, they are classified into several groups. The aim of ISO 17381:2003 is to set up criteria as to when the different kinds of ready-to-use methods may be applied for the analysis of distinct parameters in water samples (e.g. potable water, river water, process water, waste water) and which steps are necessary to prove their suitability for a certain application. Ready-to-use methods have to meet special requirements because they are often used by non-chemists. ISO 17381:2003 lists requirements for the producers of these tests, concerning safety and environmental aspects as well as handling and a description of the procedure. There are also several requirements concerning the training and supervision of the users of ready-to-use methods.