Abstract: Filter for liquid, in particular water, consisting of at least two substantially equal elements (1-4) arranged side by side and assembled to one entirety, each being in form of a rectangular parallelepiped with flat rectangular walls, whereby the inlet tubes (1e, 1f) or outlet tubes (1g) are extending horizontally through the front or rear wall of each element and tubes of all elements (1-4) lying in one or more horizontal planes are connected outside of the elements (1-4) to one or more horizontal distribution or collecting conduct(s) (7,8,9) extending along all or a number of the elements (1-4), said filter is formed as a pressure filter, whereby the housing of each element (1-4) consists of flat rectangular front and rear walls and flat rectangular upper and bottom walls, the adjacent edges of the corresponding walls of adjacent elements (1-4) are connected to each other pressure-tight and rigidly and only the first and final element (1,4) being closed by flat rectangular end walls and whereby each element