Wybrane aspekty kosztów oraz awaryjności przewodów przykładowego systemu wodociągowego

The aim of the study is to analyze cost and failures of water pipes. The analysis was conducted on the basis of operational data of the failure of the water supply network pipes, obtained from the water supply company. In the analysis, the indicator of failure rate for different types of water pipes (mains, distributional pipes and water supply connections) was accounted for. The analysis of the failure of water supply pipes in connection to the diameter, age and material was presented in the paper. The analysis can be applied in operational practice in water companies, particularly in the analysis related to the costs of pipe repairs, which consists in estimating the cost of repair work. Material composition of water supply system constitutes mainly PE and steel pipes. The new pipes are built mainly of PE. The regular replacement of cast iron pipes is noted, because of their high failure rate, which indicates that these pipes have reached the end of life technology. The obtained failure rate values were referred to the ones recommended by European criteria, as it should not exceed 0,3 failure/km a for mains, 0,5 failure/km a for distributional pipes and 1,0 failure/km a for water supply connections. In the case of distributional pipes, the failure rate exceeds the criteria and in the case of water supply connections and distributional pipes, the observed values are lower than the limit value. Repair of mains constitute 39% of all costs due to the large diameter pipes and the associated higher cost of the material. Lower total cost is related to failures, which occur on distributional pipes (23.8%) and fittings of water supply network (3.7%). The total cost of operating employees constitutes the highest of all costs. The costs incurred for materials are lower of 9.2%. Labour costs are higher than the costs of equipment by 3.6%. The data can be complementary to the national database in this area and allow to carry out a satisfactory assessment of the water supply network, taking into account both the network failure rate, as well as the tendency of changes in material supply network pipes. Despite numerous studies in the field of water supply system failure, there is still a need of conducting further study, such situation is affected by the ongoing changes in the age and structure of water supply networks. The collected data and conducted analysis can be one of the decisive indicators for the policy of operation of water supply systems.