AWWA INF52146

In Europe, rehabilitation policies for drinking water pipes are based on criteria closer to budgetary restrictions than to an authentic technicoeconomic consideration. In this reactive approach, the only rehabilitated pipes are those which have failed or have been repaired at more than a subjective rate. This approach brings about a very low rehabilitation rate and a proactive approach would be more advantageous. This paper presents different models and methods adapted to such a proactive approach. 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 the rehabilitation strategies, based on technical and economic assumptions. The first type of models use short- or long-term data maintenance records and consist of two stages. The first stage includes an analysis of the influencing factors. These factors are either specific factors such as material and diameter or environmental factors such as soil, traffic or location of the pipes. Secondly, the state of the pipe is assessed or forecasted using specific models, such as Poisson or Weibull models. They end in 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 some economic data. Previous studies on European cases are used to classify data requirements. For each model, the authors define "required data", "highly significant data" and "useful data". Previous results are provided as an illustration. In the second part of the paper, case studies are presented dealing with available data in European services. It shows that available databases remain incomplete regarding failure analysis and modeling, and rehabilitation forecasting. Includes 11 references, tables, figure.