AGING PROCESSES AND REHABILITATION NEEDS OF DRINKING-WATER DISTRIBUTION NETWORKS

Pipelines in water supply systems age slower or faster in a number of ways and for different reasons. A description is given of the causes o f deterioration in conditions which finally lead to degradation and su dden failures of system elements. The life-span or service life of a p ipeline can be extended by maintenance and repair measures and, after reconstruction and replacement, it starts practically from new. A prob ability model is proposed in which the life-span of a pipeline is cons idered as a random variable. In this model, pipelines exhibit expectan cy values for their (residual) life-span, survival and renewal probabi lities which are mathematically interrelated. An application within th e framework of a cohort survival model for pipeline types shows, for 1 0 European water supply systems, what future renewal rates result from the current system stock of the particular water utility with more or less optimistic assumptions of life expectancy of pipe types.