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This standard describes a method to determine the checmical oxygen demand (COD) of water. It applies to any kind of water. Starting with a 20 ml sample a lower analytic limit of approx. 10 mg/l can be obtained for the chemical oxygen demand. By adding silver sulphate as a catalyst most organic matter will largely be oxidized. Some nitrogen compounds are not or not completely oxidized. By adding mercury(II) sulphate, chloride will be bound, so that in most cases with carefully chose reaction conditions it will be withdrawn from the oxidation process. However, with a high chloride content in addition to a small consumption of the added potassium chromate the chloride interference will not be neutralized completely. If that is the case the influence of the interference is neutralized by an empirical correction. Bromide is oxidized to a large degree as well, which may require a separate correction (for example, in the case of sea water).