Waterfall Methodology
The Waterfall methodology is a linear and sequential approach to project management and software development. Work flows downward through clearly defined phases— similar to a waterfall—where each stage must be completed before moving to the next. This makes Waterfall ideal for projects with well-defined requirements and limited need for mid-course changes.
Goal: provide predictable schedules, budgets, and documentation, ensuring stakeholders know exactly what to expect at every phase.
Waterfall Process Steps
- Requirements Analysis: Gather and document all functional and technical requirements in a detailed Software Requirements Specification (SRS) that becomes the project blueprint.
- System & Design: Architects and designers create the overall system architecture, data models, and interface designs while selecting technologies and tools.
- Implementation (Development): Developers write the code strictly following the design and requirements documents, producing a fully functional system.
- Integration & Testing: Combine all components and perform unit, system, and acceptance testing to ensure the product meets all specifications and quality standards.
- Deployment: Release the finished product into production, conduct user training, and provide final documentation and handoff.
- Maintenance: Provide post-release support, including bug fixes, security patches, and periodic updates to keep the system stable and reliable.
Key Governance Activities
- Requirements Sign-off: Stakeholders formally approve the SRS before design begins.
- Design Reviews: Formal checkpoints to confirm architecture and design meet requirements.
- Test Plan Approval: QA team validates comprehensive testing strategies before execution.
- Change Control Board: Reviews any requested scope changes to control cost and schedule impact.
- Stage Gate Approvals: Formal sign-offs at the end of each phase to move forward.
- Final Acceptance: Client or sponsor provides formal project closure approval.
Actors (Roles & Responsibilities)
- Project Manager: Oversees schedule, budget, resources, and ensures completion of each phase before the next begins.
- Business Analyst: Collects requirements and maintains documentation to ensure traceability.
- System Architect/Designer: Defines the technical architecture and detailed system design.
- Development Team: Implements the code according to the design documents.
- Quality Assurance (QA) Team: Plans and executes all testing to validate quality and compliance with specifications.
- Stakeholders/Clients: Provide initial requirements, review deliverables at each phase, and give final acceptance.
- Change Control Board: Evaluates and approves or rejects any proposed changes.
Benefits
- Clear structure and documentation: Every phase has well-defined deliverables and milestones.
- Predictable schedules and budgets: Upfront planning allows accurate forecasting.
- Ease of management: Sequential flow simplifies tracking and reporting.
- Good for stable requirements: Works well when requirements are fully known and unlikely to change.
Cons
- Inflexible to changes: Adjusting requirements mid-project is costly and time-consuming.
- Late discovery of issues: Problems often surface during testing, when fixes are more expensive.
- No early working product: Stakeholders see a finished product only at the end of the cycle.
- Poor fit for evolving needs: Not ideal for projects with dynamic or unclear requirements.
Summary
Waterfall provides a disciplined, phase-driven framework for projects that demand predictability, formal approvals, and comprehensive documentation. It excels when requirements are fixed and technology is well understood, but its rigidity makes it less suitable for fast-changing or exploratory initiatives.