Organic pollutants in effluent require oxygen to be completely chemically oxidized. Hence the pollutant load of wastewater can be measured through the chemical oxygen demand (COD), expressed in tonnes of oxygen required.

The sector has reduced its specific COD load by 75% since 2001. By continuing to implement the best available techniques for wastewater treatment, the sector is able to produce more while maintains a stable COD level of its effluents.

Process wastewater in the chemicals and life sciences sector is typically treated either in public wastewater treatment plants (funded through the payment of taxes) or, more importantly, in-house, where wastewater treatment plants can be shared between companies. The reported COD values relate to wastewater released by the industry into surface waters.