Drainage network maps of the Berliner Wasserbetriebe were predominantly used as a basis to describe the type of drainage as well as the different catchment areas of rain water drainage. Drawing on the latest drainage network maps from 2001, reflecting the state of affairs at about 2000, the “Management of rain and waste water map”, worked out as early as in 1992 as part of the environmental atlas was upgraded. This particular map had been digitised already towards the late nineties. Help also came from the map “Attachment 1: Periods of waste water facility development in settled areas (October 2001)” of the Abwasserbeseitigungsplan (waste water disposal plan) which offered schematic drawings of those areas which were connected to the sewage network after 1990.
This collection of descriptive data also benefited from information drawn from the information system City and Environment IX B 2 (Land use, surface sealing as of December 2001) as well as from the STEP (City development plan) concept for water supply and disposal (Senate Administration for urban development I C: Sewerage and types of sewerage as of 1999) and the water body register.