A filter for attachment to a pump inlet fitting and retention post with a post cross section, the filter comprising: a filter body made of porous material; a plastic outlet port (520, 520A) attached to the filter body for connecting the filter to the inlet fitting, the outlet port having a flow axis defined by an intended direction of fluid flow from the filter to the pump; and a plastic retainer formed on the outlet port (520, 520A), the retainer comprising a tab (536, 536A) extending in a plane perpendicular to the flow axis, the tab having a first surface facing the pump and a second surface facing away from the pump, the tab extending continuously around the entire periphery of the outlet port (520, 520A); wherein the tab (536, 536A) includes at least three apertures (534, 538A) located radially around the outlet port (520, 520A) for receiving the retention post, the apertures extending from the first surface to the second surface, the apertures (534, 538A) having an effective cross-section smaller than the retention post cross-section in at least one radial plane intersecting with the flow axis between the first and second surfaces including the second surface, wherein the tab (536, 536A) has a flower-shape with at least three petals defining the at least three apertures (534, 538A) therein; wherein the outlet port (520, 520A) further includes a cylindrical outlet and a base flange extending radially outwardly from the cylindrical outlet, and wherein, in the flow axis, the tab (536, 536A) is spaced away from the base flange; wherein the plastic retainer includes an anti-rotational positioning tab connected both directly to the base flange and directly to the tab (536, 536A), wherein the tab (536, 536A)is projecting radially outwardly from the outlet port (520, 520A), wherein an inside edge of the anti-rotational positioning tab is spaced away from the cylindrical outlet to provide space and clearance for the maximum length of the retention post. a filter body made of porous material; a plastic outlet port (520, 520A) attached to the filter body for connecting the filter to the inlet fitting, the outlet port having a flow axis defined by an intended direction of fluid flow from the filter to the pump; and a plastic retainer formed on the outlet port (520, 520A), the retainer comprising a tab (536, 536A) extending in a plane perpendicular to the flow axis, the tab having a first surface facing the pump and a second surface facing away from the pump, the tab extending continuously around the entire periphery of the outlet port (520, 520A); wherein the tab (536, 536A) includes at least three apertures (534, 538A) located radially around the outlet port (520, 520A) for receiving the retention post, the apertures extending from the first surface to the second surface, the apertures (534, 538A) having an effective cross-section smaller than the retention post cross-section in at least one radial plane intersecting with the flow axis between the first and second surfaces including the second surface, wherein the tab (536, 536A) has a flower-shape with at least three petals defining the at least three apertures (534, 538A) therein; wherein the outlet port (520, 520A) further includes a cylindrical outlet and a base flange extending radially outwardly from the cylindrical outlet, and wherein, in the flow axis, the tab (536, 536A) is spaced away from the base flange; wherein the plastic retainer includes an anti-rotational positioning tab connected both directly to the base flange and directly to the tab (536, 536A), wherein the tab (536, 536A)is projecting radially outwardly from the outlet port (520, 520A), wherein an inside edge of the anti-rotational positioning tab is spaced away from the cylindrical outlet to provide space and clearance for the maximum length of the retention post.