When working at regional, transboundary, national or basin level, the creation of a water information system to produce information never starts from scratch.

The following always already exist:

- Data producers with their own staff and data-collection procedures;

- Operational information systems with specific procedures and data structures for digitizing/controlling/archiving/processing the data;

- Data/information exchanges between organizations following specific procedures.

Therefore, in order to build on existing systems and not reinvent the wheel when organizing a new water data management process, the following are recommended:

- Adopt some basic principles to ensure successful cooperation between actors;

- Start with a diagnostic phase that could help to identify:

• The real needs to be covered in terms of information production;
• The actors/institutions involved in data production/ management and information use and their specific roles;
• The datasets that exist and the information systems already set up, and the conditions to access and use the data (level of confidentiality, technical conditions of access, etc.);
• The existing data and information flows already established between the partners;
• Partners’ needs in terms of data access, reinforcement of their tools, developing the capacity of their human resources, and what could encourage them to participate in a process of regular data exchange.

In many cases, it might also be important to:

• Diagnose of the existing situation on data management
• Develop elements of common language in order to insure the comparability of data exchanged
• Establish procedures facilitating interoperability between the existing water information systems