Water quality is controlled throughout the adduction/transport system by collecting water samples in representative sampling points of EPAL's adduction/transport system in order to assess the evolution of water quality throughout its transport (exit from treatment plants, representative mixed water adduction system points for different origins, and water delivery points to Lisbon's Distribution Network) so that results may be screened within a total of 60 sampling points.

EPAL's adduction system operational control comprises water mains, reservoirs, pumping stations, water treatment plant exits, representative mixed water adduction system points for different origins, and water delivery points to Lisbon's Distribution Network.