Abstract: A pump assembly for use with an open end volumetric container having at least a vertical portion which defines a height of the volumetric container. The pump assembly includes a substantially hollow body portion having first and second ends. A plunger member extends slidably through the first end. An inlet valve is adjacent to the second end and opens into the body. An outlet valve opening out from the body is also provided. The assembly also includes an assembly for mounting the pump assembly on the container vertical portion with the body second end positioned within the volumetric container.