Chemical Oxidation Demand (COD) is a test that measures the amount of oxygen required to chemically oxidize the organic material present in water. It measures the organic compounds in applications such as lakes, rivers or wastewater which have been contaminated by domestic or industrial waste. The most commonly adopted method involves the addition of potassium dichromate and concentrated sulphuric acid to the water sample with oxygen concentration measured before and after.
COD does not necessarily measure the same types of oxygen consumption. For example it does not measure the oxygen-consuming potential associated with certain dissolved organic compounds such as acetate.
Many governments impose strict regulations regarding the maximum COD that wastewater discharge can exhibit.