Abstract: The instant invention provides a method and apparatus for the verification and calibration of pumping rates in systems having a volumetric pump drawing fluid from a tank. An effluent valve is connected to the base of the tank and in turn the valve is connected to the base of a calibrated column. The column is also connected at its top to the top of the tank thereby providing equalized pressure conditions within the column and the tank. A sight level gauge mounted on the calibrated column, or a transparent calibrated column alone, may be used to determine the liquid level. The liquid levels in both the calibrated column and tank are continually at equilibrium during normal pumping operations. In order to operate the invention, the effluent valve is closed and the decrease in the level of the fluid in the calibrated column is measured during a timed interval to determine the pumping rate.