At a glance
- One of the oldest and best-known process models in project management.
- Linear, step-by-step process with no provision for returning to earlier phases.
- Particularly suited to projects with stable requirements and clear objectives.
- The basis of many modern process models – and a counter-concept to agile methods such as Scrum.
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Waterfall model definition
The waterfall model is one of the oldest and best-known process models in project management and software development. It describes a linear, sequential process in which a project is worked through step by step in defined phases – similar to a waterfall flowing from level to level.
Each phase has clearly defined objectives, deliverables and acceptance criteria. Only when a phase is fully completed does the next one begin. Returning to earlier phases is not envisaged in the classic waterfall model – which is both a strength and a weakness of the model.
„For the rollout of our standardized management reporting, the waterfall model was exactly the right choice. The clear phases gave us planning reliability, and with DeltaMaster we had transparent visibility of budget and progress at all times.“Head of Controlling
Industrial company
Structure and phases of the waterfall model
Typically, the waterfall model is divided into several clearly defined project phases. As a rule, returning to a previous phase is not intended.
The classic phases of the waterfall model include:
- 1. Requirements analysis: In this phase, all requirements for the project or software are fully documented and defined.
- 2. System and software design: In this phase, the architecture is planned and the software design is created based on the requirements.
- 3. Implementation: In this phase, the actual development or programming takes place.
- 4. Testing phase: To find errors and verify functionalities, the developed system is thoroughly tested in this phase.
- 5. Integration and maintenance: After a successful testing phase, the system is put into practice and maintained if necessary.
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Advantages of the waterfall model
The waterfall model is convincing due to its clear structure and simple planning. Each phase in the waterfall model has distinct goals and results, which improves documentation and traceability. The model offers advantages especially for projects with stable requirements and clearly defined goals.
The advantages of the waterfall model include:
- clear project structure and fixed processes
- simple planning and control
- good documentation and traceability
- ideal for projects with few changes
Disadvantages of the waterfall model
The model reaches its limits especially in projects with uncertain or changing requirements, as the waterfall model is often considered too rigid and inflexible. Particularly in modern software development, changes during the course of a project are difficult to implement, since returning to previous phases is usually complex or not intended at all.
The disadvantages of the waterfall model include:
- hardly flexible when changes occur
- late error detection only in testing phases
- higher risk in complex or innovative projects
- low customer involvement during development
Waterfall model vs. agile methods
The waterfall model differs from agile project management methods in various aspects:
| Characteristic | Waterfall model | Agile methods (e.g. Scrum) |
|---|---|---|
| Approach | Linear, sequential | Iterative, incremental |
| Plannability | High – everything planned in advance | Low – continuous adjustment |
| Flexibility | Low | High |
| Customer involvement | Low – mainly at the beginning and the end | High – continuous feedback |
| Error detection | Late – usually in the testing phase | Early – after each sprint |
| Documentation | Extensive, phase-based | Lightweight, ongoing |
| Suitability | Stable requirements, clear goals | Dynamic requirements, innovation projects |
| Typical industries | Construction, hardware, regulated industries | Software development, product development, BI |
When is the waterfall model useful?
The waterfall model is particularly suited for:
- Projects with clearly defined, stable requirements, when the goals will not change
- Regulated industries, where extensive documentation and traceability are mandatory (e.g. medical technology, aerospace, public administration)
- Construction projects and technical systems, where physical processes are inherently sequential
- Projects with fixed contractual structures, where scope, costs and schedule are contractually defined
For software projects with changing requirements or for agile teams, methods such as Scrum or Kanban are usually better suited. Hybrid approaches combine the planning reliability of the waterfall model with the flexibility of agile methods.
Application examples: Where is the waterfall model used?
The waterfall model is suitable above all for projects with stable requirements and a high need for documentation. The following areas show typical fields of application.
Where would you like to use the waterfall model?
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Bissantz and waterfall models
In the practice of BI implementation projects at Bissantz customers, it becomes clear that the choice of process model depends heavily on the type of project.
When the waterfall model makes sense for BI projects: Projects with clearly defined reporting requirements, stable data models and a fixed schedule – such as the introduction of standardized management reporting or the migration of an existing data warehouse – benefit from the planning reliability and clear phase structure of the waterfall model. Requirements are captured in full, the data model is designed, implemented, tested and rolled out.
When agile methods are superior: When requirements take shape in the course of the project – for example in the development of new analysis dimensions, AI-supported commenting or the iterative design of dashboards – sprint-based approaches such as Scrum are more effective. Business users can provide feedback after each sprint, and reports are refined step by step.
DeltaMaster supports project controlling regardless of the chosen process model: budget, progress and resource use are made transparent – automatically, up to date and ready for decisions.
| Function | Benefit |
|---|---|
| Project controlling | makes budget, progress, and resource use transparent |
| Automatic updating | delivers current, decision-ready project metrics |
| Methodology-independent support | accompanies both waterfall and agile projects |
„During our data warehouse migration, the fixed phase structure allowed us to stay on schedule. The project controlling in DeltaMaster helped us manage resource allocation in a traceable way.“Head of IT
Financial services provider
Frequently asked questions
What is the waterfall model explained simply?
The waterfall model is a project method in which all steps are worked through one after another – like a waterfall flowing from top to bottom. First all requirements are defined, then planning takes place, then development, then testing, then rollout. Each stage must be completed before the next one begins. This provides clarity and structure – but works best when the requirements do not change.
What is the difference between the waterfall model and Scrum?
The waterfall model plans everything in advance and works through it linearly – there is one result at the end of the project. Scrum works iteratively in short sprints – after each cycle there is a functional intermediate result that can be adjusted. Waterfall offers more planning certainty, Scrum more flexibility and early customer feedback.
Is the waterfall model outdated?
Not fundamentally – it still makes sense in many industries and project types. In modern software development it has largely been replaced by agile methods, because requirements there change frequently. In regulated industries, in construction, or for projects with fixed contract structures, the waterfall model remains relevant – often also as a basis for hybrid approaches.
What is the difference between the waterfall model and the V-model?
The V-model is a further development of the waterfall model: it complements each development phase with a corresponding test phase – the phases run not only sequentially but in a V-shaped pattern. This integrates quality assurance more systematically. The V-model is especially common in software development and in safety-critical areas.
How is the waterfall model used in BI projects?
For BI projects with clearly defined requirements – such as standardized management reporting or data warehouse migration – the waterfall model offers planning reliability. For iteratively developed dashboards and analyses, agile methods are often superior. In practice, many projects combine both approaches: classic phases for the technical infrastructure, iterative development for the analytical content.
Summary
The waterfall model is a proven process model for projects with stable requirements, clear objectives and a high need for documentation. Its linear structure offers planning reliability and traceability – but reaches its limits with dynamic requirements. DeltaMaster from Bissantz supports transparent, data-based project controlling regardless of the process model.
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