A foot operated pump includes a water and airtight flexible and collapsible wall between a top plate and a base plate and an interior variable volume chamber. A flexible hose is selectively attachable to either an inlet port or an outlet port on the top plate member. The contents (air and/or liquid) within the variable volume chamber are forced out of the outlet port upon forced downward movement of the top plate member towards the base plate member. As the top plate member returns to a normally relaxed state in separated, angled relation to the base plate, the variable volume chamber enlarges and air is sucked through the inlet port to fill the variable volume chamber. An opposite end of the flexible hose attaches to various adapters and fittings for clearing clogged drain lines and other conduits.