Abstract: An automatic pneumatic pump preferably used with a waste water disposal system is disclosed. The pump forcibly introduces sludge-laden liquid into a tank (30) and in turn feeds the liquid to a filter unit (F) for filtering off the sludge. The pump has one air pressure pipe (61) and two air exhaust pipes (62, 63) provided to the upper portion of the tank (30). The air pipes (61 to 63) include their solenoid valves (71 to 73) which are selectively opened in accordance with the liquid level inside the tank (30). An air compressor (C) is mounted to the air pressure pipe (61) and selectively operated during a time when the liquid level inside the tank (30) reduces from a top level to a bottom level (S.sub.1). A vacuum pump (P.sub.2) is mounted to the second air exhaust pipe (63) and selectively operated during a time when the liquid level inside the tank (30) increases from the bottom level (S1) to the top level (S.sub.2).