Reducing of the hydraulic characteristics of pressure pipelines in the course of their operation due to corrosion, clogging and other causes leads to an increasing of operating costs. The existing information on the change in the capacity of pipelines under the influence of certain factors is currently insufficient. The aim of the work is to determine the influence of the clogging degree of the pipeline on its throughput. This paper describes the results of hydraulic tests of a pressure pipeline with clogging of two types: expanded clay gravel and medium-grained sand. The discharge coefficient and resistance coefficient of the "clean" pipeline and the pipeline with clogging were determined during the experiments. The dependence of the relative flow rate of the pipeline on the clogging degree of the pipe was obtained. Influence of the type of filler on the throughput of the pipe was shown. An insignificant difference in the values of the relative flow rate for both fillers at low degrees of clogging of the pipeline was established. The transition from the discharge and resistance coefficients to filtration coefficients of pipeline was proposed. The values of the filtration coefficients of pipe from the experiments on the flow measurement were found. The ratio between the discharge coefficient and the filtration coefficient of pipeline was set. The values of filtration coefficients of pipe for emptying the pressure tank were found. The coincidence of the values of the filtration coefficients by the two methods was obtained.