Filter assembly for a liquid medium comprising a two-piece filter housing having a first and a second housing part with a first and second end wall respectively, surrounded by a circumferential wall, said housing parts accommodating in the space defined between the end walls three layers of filter material, and with a spacer in-between having an open structure with upstanding ribs defining chambers there between and having two end planes which define abutment planes for two layers of filter material and with a passage crosswise to the plane thereof, and with between the second layer of filter material and the second end wall a third layer of filter material, in which all three layers of filter material are discrete layers, the space between the third layer of filter material and the second end wall, and the chambers in the spacer, being in connection to the filter outlet, and the space between the first layer of filter material and the first end wall being connected to the filter inlet.