A method and apparatus for filtering pressurized fluids, wherein a fluid level provides a visual indicator as to the general condition of the filter element. The present invention provides a vertical housing having a fluid inlet for communicating the fluid into said housing and a fluid outlet for communicating the fluid downstream of the housing. A filter element is disposed within the housing between the fluid inlet and the fluid outlet for filtering the fluid. The volume of air within the vertical housing is specifically determined in order to maintain a level of fluid which will indicate the general condition of the filter element.