There are many examples of models and expensive softwarel, which have been used only a few times by the client organization and then have been considered obsolete. As early as in the planning phase, when the need for a DSS is realized, the constant use and maintenance of the system has to be considered and the conditions for a continued benefit from the DSS have to be listed, itemized and assessed. The overall condition is the 'need' for a DSS. The organization embarking on a DSS project must have a strongly felt need at the management level. Scarce water resources, competition for water, serious water pollution and frequent risks (floods and droughts) will make decisive management responses necessary and emphasize the need for a DSS to support IWRM approaches. Key considerations on the sustainability of a DSS are given below.

1. Requirements of software, supplier, and client

• The client should have clear 'ownership' of the DSS, which requires that it is developed in a participatory manner and riparian countries need to acknowledge the validity of the model results to inform the decision-making processes
• The gap between the 'modelers' and the users should be bridged by defining how the system will be used and making sure that the model software can simulate the defined situations
• The DSS framework should be open-ended to support changes and new needs
• The DSS software must support efficient knowledge/information sharing and stakeholder participation through web solutions
• The DSS must support the use of new or emerging technologies for data and information capture and accommodate different levels of data availability
• The DSS must be flexible and able to provide solutions which match the technical capabilities of the receiving institution
• The software provider must be capable of responding to urgent needs for new codes or functionality
• The software supplier must be able to provide continuous and long-term technical support and maintenance.

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2. Organizational requirements

• The DSS needs to be anchored in an appropriate department with staff with technical knowledge of IWRM
• The DSS team needs to have their responsibilities clearly defined
• The DSS department needs to have strong links to the management level regarding delivery of analyses, assessments and recommendations on IWRM
• The organization needs to have an IT support function
• The organization needs to have strong links to sector stakeholders in order to accommodate their development plans and water requirements
• The organization needs to have a communication team to ensure that the public is sufficiently involved, e.g. through workshops and web sites – SharePoint discussion forums, etc.

3. Training requirements

• New technical staff need to be trained continuously to maintain a highly qualified, experienced DSS team
• Incentives and career planning should be established to keep existing staff and recruit new staff
• Training in new codes and new functionalities should be received from the software supplier.

4. Financial requirements

• Funds must be available to request services from the software supplier and/or the consultants, e.g. for technical support and upgrading of the DSS, or for applying the DSS to new projects
• Funds must be available to sustain a DSS team in the appropriate department
• Funds must be available to upgrade computer/IT equipment regularly and to pay for Internet services
• If appropriate, the DSS team can create revenue by delivering services to other agencies/organizations.

Thus, it is clear that the institutional and financial environment in which the DSS will function is just as important as the functioning of the model codes and other software. (GWP 2013b)