The introduction of electricity certificates has increased the interest in development of flow measuring techniques to verify efficiency improvements after refurbishments in Swedish low head hydraulic machines. At Luleå Univeristy of Technology Jonsson [1] and Lövgren [2] have been working with development of the pressure-time method. The present work presents an evaluation of a flow measuring method known as the volumetric method. The method consists in running a turbine at a constant load during an extended period of time which depends upon the reservoir geometry. The flow rate through the turbine is determined from the volume change in the reservoir(s) by measuring the water level change. Through a pilot study in a full scale machine it is shown that the method reproduces reasonable results. The measured flow rate deviates by less than 3% from the value reported in the hydropower plant. The accuracy of the reported flow rate and the one measured in here is however difficult to determine and left unconsidered in this work. For future studies of the method it is recommended to more thoroughly investigate how accurately the rate of change of water level along with the reservoir area can be determined.