Models are used in all sectors of water management. They have become a valuable tool for decision making, operation of plants and networks, and in education.

From the papers presented at the Aquatech 1998 conference in Amsterdam it is evident that modelling has become a mature activity. There seem to be no fundamental bottlenecks, and a wide range of successful applications have been demonstrated in the papers selected for these proceedings. 

The papers deal with applications in drinking water, sewerage, wastewater treatment and surface water quality. This enables a good overview of the status of modelling applications in each field to be obtained.

It is increasingly likely that the success of the application of models in the separate water sectors will lead to the use of these models for integrated water management.