The increasing complexity of water management has generated a rapidly growing demand for information and also for Geohydrological Information Systems (GhIS). An information system for water management must relate directly to the water manager's tasks. To be able to implement these tasks effectively the water manager requires information about the properties of the water system and about society's interests and needs. As well as providing information, a GhIS for water management should have analytical tools for interpreting and analyzing data and information, so it also has functions for acquiring, storing, processing, checking, interpreting and analyzing data. TNO Institute of Applied Geoscience is developing GhIS that have these functions and in which the integration of information and functionality, the flexibility, and the transferability and utility for different user groups are also important aspects.