The analysis of an aerated, diluted sample for its BOD involves the determination of its dissolved oxygen content before and after an incubation period. The difference between the initial dissolved oxygen and the final oxygen content represents the oxygen demand of the sample. The oxygen demand of incinerator quench water (or similarly polluted water) is exerted by three classes of materials: (a) carbonaceous organic material usable as a food source by aerobic organisms; (b) oxidizable nitrogen derived from nitrite, ammonia, and organic nitrogen compounds which serve as food for specific bacteria (e.g. Nitrosomonas and Nitrobacter); and (c) certain chemical reducing compounds (e.g. ferrous iron, sulfite, and sulfide) which will react with molecularly dissolved oxygen. Since incinerator quench water may contain many variables which affect the Winkler Method of analysis, the Dissolved Oxygen Analyzer Method is recommended for BOD analysis of all quench water sample. The Alsterberg (Azide) Modification of the Winkler Method is recommended for standardization of the Analyzer using the relatively pure dilution water. The sampling location at each site is very important in the evaluation of the data. The sampling site should be chosen on the basis of obtaining the most representative sample.