CARE-S comprises a suite of tools, which provides the most cost-efficient system of maintenance, repair and rehabilitation of sewer networks, with the aim to guarantee security of sanitary sewage collection and storm water drainage in order to meet social, health, economic and environmental requirements. This has been done within the context of integrated catchment management and the strategic objective of ensuring security of water resources.

Sewer and storm water systems in European cities suffer from insufficient capacity, construction flaws and pipe deterioration. The consequences are structural failures, local floods (a particular problem being basement flooding), traffic disturbance, street and surface erosion, and pollution of local receiving waters. The problems arise because of the combination of ageing infrastructure and increased urbanisation. Urbanisation affects the balance between surface runoff and groundwater level, and leads to an increase of both, runoff volume and intensity. Additionally, the frequency of high intensity rainfall appears to be increasing in many regions and climatologists predict climate changes that will increase the problem further. European cities spend in the order of five billion Euro per year for wastewater network rehabilitation. This amount is expected to increase significantly over the coming decades, due to network ageing. Out of the EU allocation for the Regional fund, typically 20% may be spent on water and wastewater systems of which wastewater networks cause larger costs than water distribution systems.

For wastewater network managers the main problems to be solved are:

•   Keeping sewage and storm water as a resource that, if possible, should be reused.
•   Reducing pollution affecting local receiving waters as well as main watercourses and groundwater
•   Reducing clean water infiltration/inflow in the network and its adverse impact on sewage treatment
•   Preventing local floods, affecting buildings (basements flooded) and traffic (streets flooded)
•   Preventing structural collapses, affecting wastewater services and road traffic (streets damaged) and damaging other sub-surface infrastructure
•   Preventing pollution of water supply systems, due to infiltration of sewage

In worst cases, these problems can have life-threatening consequences, and their solution is always extremely costly and disturbing.