Adolfo Suárez Madrid-Barajas airport has differentiated channels for treating waste water on the one hand, and stormwater, on the other, in order to avoid any possible discharge of contaminants and hazardous substances into the public water system.

The quality of waste water discharged into the municipal sewage system is controlled by periodical samplings at the different discharge points.The samples are used to analyse the main legislated contaminants in certified laboratories.

The airport also has an aircraft bilge water treatment plant, which purifies using physicochemical treatment before being discharged into the municipal collectors.