The total amount of water to be abstracted by 1985 directly or indirectly from the river Meuse in Belgium and the Netherlands for water supply purposes, is estimated at 800 million m 3 . This prospect makes preservation of river water quality of the utmost importance. A detailed water quality surveillance system, covering the Belgian part of the Meuse river basin, was worked out in the early sixties by the water supply company of Antwerp. The present state of the surveillance system is described. General features of the water pollution pattern in the river are discussed, with emphasis on pollution by heat, suspended solids, organic substance and salts.