Task 3.1   Technical and economic criteria

There are a variety of methods to rehabilitate water networks. The method to be chosen obviously depends on local conditions, such as the type of the problem, the size of the pipe etc. The rehabilitation costs are linked to the applied method and technology. In addition to the cost of the technical solution, a rehabilitation project will also lead to expenses for indirectly involved parties due to traffic disturbances, temporary water losses and other inconveniences. These costs are normally referred to as "indirect" (when tangible) or "social costs" (when intangible). Research has been carried out to identify such costs, and procedures have been proposed to estimate them under given circumstances. The current state of the art on indirect and social costing has been applied in this project.
Rehabilitation cost data do exist, but have not been systematically analysed and documented for all-European conditions. The comprehensive network of project partners and end-users, established in this project, was used to collect data on direct rehabilitation costs. The research covered various conditions, including south/north and central-east/west Europe, city centres, sub-urban and rural districts. Actual replacement costs were compared to estimated repair costs in order to create rules for the optimum timing for action. The costs included technical as well as social factors.

Task 3.2   Other criteria

Additional to pipe failures, service reliability and cost criteria, there usually exist some other reasons for rehabilitation, such as political priorities, adjacent constructional works (road reconstruction) etc. CARE-W includes routines for such events in the general decision support.

Task 3.3   Multi-criteria decisions

Existing tools for multi-criteria analyses was prepared for water network rehabilitation, tested and included in CARE-W. A special workshop was held including end-users to document, weigh and select criteria for decision making.

Task 3.4   Procedure for defining rehabilitation programmes

This procedure was established based on pipe failure forecasting and water supply service reliability analyses, total costing and other criteria, and the multi-criteria decision support tool. The proposed procedure was included in the CARE-W prototype.