Failure of water supply networks in selected Polish towns based on the field reliability tests

Abstract

The field reliability test conducted in the real operation conditions is the basis of water networks unreliability assessment. This kind of tests has being conducted in Poland for over 35years. The latest results of the tests for water networks in the biggest cities in Poland have been presented in this article. Data concerning failures of the pipelines in these three cities have been gathered in the Geographical Information Systems. The unit intensity of failures λ (failures/kmyear) was used for pipeline unreliability/reliability assessment. This kind of index is very useful for assessment and reliability/unreliability of different pipelines comparison. In particular the unit intensity of failures allows the preliminary assessment of pipelines technical state, which facilitates making decision about renewal of pipelines. This kind of index plays a very important role in the decision making procedure of material selection to network construction. Analysis of the intensity of failures values from the last 10years of networks operation period showed that Polish networks unreliability decreased close to 3 times. Although the progress of failures intensity of Polish networks is much higher than intensity of failures of networks in many European countries. The influence of the main factors i.e. instability of ground, values and variability of the water pressure in network, as well as pipeline material on failure frequency of the water network was also presented in the paper.