本文件规定了在培养5d或7d后，通过稀释和接种抑制硝化作用来测定水的生化需氧量。 它适用于所有生化需氧量通常在1 mg/l和6000 mg/l之间的水。它特别适用于废水，但也适用于天然水的分析。对于大于6000 mg/l氧气的生化需氧量，该方法仍然适用，但需要特别注意，考虑到准备稀释步骤的二次取样的代表性。 所获得的结果是生物化学和化学反应的产物，在存在生物物质的情况下，生物化学和化学反应的表现只是偶尔的再现性。这些结果并不像单一的、定义明确的化学过程所产生的结果那样严格、明确。然而，这些结果提供了一个可以估计水质的指标。

This document specifies the determination of the biochemical oxygen demand of waters by dilution and seeding with suppression of nitrification after 5 d or 7 d incubation time. It is applicable to all waters having biochemical oxygen demands usually between 1 mg/l and 6 000 mg/l. It applies particularly to waste waters but also suits for the analysis of natural waters. For biochemical oxygen demands greater than 6 000 mg/l of oxygen, the method is still applicable, but special care is needed taking into consideration the representativeness of subsampling for preparation of the dilution steps. The results obtained are the product of a combination of biochemical and chemical reactions in presence of living matter which behaves only with occasional reproducibility. The results do not have the rigorous and unambiguous character of those resulting from, for example, a single, well？defined, chemical process. Nevertheless, the results provide an indication from which the quality of waters can be estimated.