The emphasis on sewerage has nearly always been on serious structural defects. With the new EU legislation that demands sewer water tightness and the need to reduce the costs associated with infiltration, wastewater utilities are now considering in more depth the problem of sewer deterioration. Closed Circuit Television (CCTV) inspection is by far the most common method utilized for the inspection of sewer networks. Existing software on sewer evaluation based on CCTV inspection results include rating systems that do no more than act as a coarse filter for a closer examination of the results of CCTV surveys.

The pivotal question in all CCTV surveys is how to translate what is seen into a program of action.