Abstract: An automatically self-flushing filter for use on overhead sprinkler irrigation systems, and the like, is disclosed. The filter includes a hollow cylindrical body (20), a removable screen element (30) mounted within the body (20), and a plunger (40) suspended within the body (20) by a length of elastic tubing (50). The plunger (40) is positioned for reciprocal movement through a debris outlet (28)between a retracted or debris discharging position, wherein the outlet (28) gap has a maximum width, and a filtering position, wherein the outlet (28) gap is closed. The plunger (40) is moved to its filtering position by pressurized water flowing through the body (20). Simultaneously, the water is filtered through the screen element (30) and passes out the clean water outlet (37) while debris accumulates within the body (20). When the water supply is shut off and the water pressure decreases, the plunger (40) is retracted to its debris discharging position.