A self-cleaning, back-washable filter apparatus and method for use with a pumping apparatus which is lowered into a well casing. The filter apparatus includes a filter basket having a manifold with several tubes extending therefrom. A filter sock encases at least a portion of the filter basket to block sand or other solid particles from entry into the pump intake. Pressurized gas or fluid is directed to the manifold and then through perforations or jets distributed along the length of the tubes. Bursts of the pressurized gas are directed from the perforations or jets to the interior of the filter apparatus and then sprayed from the perforations or jets in an outwardly direction against interior surfaces of the filter sock. Air or fluid bursts from the perforations impinge upon the interior surfaces of the filter sock and dislodge or expel entrapped particulate material.