Water infrastructure management: an overview of european models and databases

In Europe, rehabilitation policies for drinking water pipes are based on criteria closer to budgetary restrictions than to an authentic technique-economic consideration. In this reactive approach, the rehabilitated pipes are only those that have failed or have been repaired at more than a subjective rate. This approach brings about a very low rehabilitation rate and does not allow the assessment and the management of risks. At first, this paper presents different models and methods adapted to preventive and "pro-active" approaches that should be developed in water utilities. These models were created in different European research centers and Universities. They can be classified into two major types according to their objectives: models assessing the structural state of the pipes based on statistical methods and models assessing and comparing rehabilitation strategies, based on technical and economic assumptions. The first type use short or long-term data maintenance records. They are made up of two stages: first an analysis of the influencing factors is produced. These factors are either specific factors such as material and diameter or environmental factors such as soil, traffic or pipe location. Secondly the state of the pipe is assessed or forecasted using specific models, such as Poisson or Weibull distributions. They conclude by classifying pipes either in groups or pipe by pipe. The second type of model requires a description of the network (age, length, material and failure rate) and integrates economic data. Previous European case studies are used to classify data requirements. For each model, we define "required data", "highly significant data" and "useful data". Previous results are given as illustration. In the second part, we present case studies about available data in European services. It shows that available databases remain incomplete regarding failure analysis and modeling, and rehabilitation forecasting.