Results obtained from water analysis form the basis for numerous decisions in the fields of health protection and environmental management. The reliability of analytical results plays an important role. Therefore, within the context of quality management, every laboratory shall establish a quality assurance system encompassing both internal quality assurance tools (such as method validation, use of control charts) and external quality assurance measures (such as participating in interlaboratory trials). This standard specifies quality assurance methods to be applied in the introduction and routine performance of chemical and physicochemical analytical procedures in water analysis. Relating to prestandard DIN V ENV ISO 13530:1999-10, which was withdrawn in 2010-04, instead of a general manual referring to quality assurance, a standard providing clear instructions has been prepared into which further calibration procedures, plausibility control, monitoring periods of test equipment have been incorporated. An Excel spreadsheet for performing the test for 6 to 30 measuring data for normal distribution in accordance with Annex B is available for download at the Water Practice Standards Committee (NAW) homepage at DIN.