Failure of water supply networks in selected Polish towns based
on the field reliability tests
The field reliability test conducted in the real operation conditions is the basis of water net-works unreliability assessment. This kind of tests has being conducted in Poland for over
35 years. 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 k (failures/km year) 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
10 years 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