The right sewer rehabilitation technology, in economic as well as in technical terms, is chosen from a defined catalogue of technologies fulfilling the requirements under specific local conditions. Characteristics are systematically analysed and documented for a variety of open trenching and no dig rehabilitation technologies. Beyond the direct costs, the decision support system takes into account a multitude of other factors, which are usually collected by wastewater companies preparing a public tender on a specific rehabilitation project. Although from a financial point of view, the waste water company would choose the lowest bid, it has also to consider external costs that are not charged directly to the waste water company, such as impacts on trades or traffic disturbances for road users. This paper presents the application of Strassert's balancing and ranking procedure to the problem of choosing the right sewer rehabilitation technology. The procedure is implemented into computer software that is directly linked to a data base of rehabilitation technologies. It is tested against case studies from various European sewer networks. The work presented is carried out within CARE-S (Computer Aided REhabilitation of Sewer and storm-water networks), a project under the EU 5th framework programme.