The waterfall methodology is one of the most well-known project management methodologies you can use to guide your process and project phases. It can be extremely effective due to its meticulous planning, attention to detail and linear implementation.
In this article, we explain what the waterfall methodology is, list the stages employed in this cascading method, compare it to the agile approach to project management and software development, and detail some of the waterfall methodology’s advantages and limitations.
What is the waterfall methodology?
Waterfall methodology, sometimes referred to as the linear sequential life cycle or waterfall model, is a project management method that approaches development in a linear and sequential, or cascading, order. When using this method, project development teams follow a progression of logical steps throughout the software development life cycle (SDLC). The process only progresses to the project’s next phase once the previous step has been completed.
Even though its popularity has diminished over the years in favor of increasingly more agile methodologies, the waterfall model’s logical nature and simple implementation maintain its prevalence in the industry. When using this method, customer and stakeholder requirements are collected at the start of the project and then used to develop a sequential plan to accommodate them. Though most commonly used in software development, the waterfall methodology can also be used in various other IT projects as well as in construction.
Stages of the waterfall methodology
The waterfall methodology has an inherently methodical nature that leads a project through straightforward steps. There are typically five to seven phases in this method. Though the specific names and number of steps can vary depending on the developer or project, the concepts usually remain the same. Here are the basic phases of the waterfall model:
The customer requirements for the end product are gathered at the beginning of the project and compiled into a requirements document to guide the process. These requirements generally list what the application should do without considering how it will be accomplished. By gathering the requirements at the start of the project, it eliminates the need for further customer involvement and allows the team to plan every other phase.
This is the stage when you review the requirements and develop a design to meet them. Once the requirements have been gathered, the system is then evaluated to gauge the tools needed and to create the models that will be used in the finished application. Here, your team identifies the path it will take to deliver a solution and the relevant specifications.
The design phase can be broken up into two subphases: logical design and physical design. During the logical design subphase, solutions are brainstormed to meet the desired requirements. It is during the physical design subphase that the theoretical ideas are transformed into concrete plans and design specifications, such as services, data layers and programming languages.
It is during this phase that the actual code is written to meet the specifications, models and requirements that were outlined in the previous phases. Some testing may take place, and if significant changes are required during this stage, this may mean going back to the design phase.
Once the code has been written, beta testers, quality assurance and any other relevant testers explore the application systematically to discover any issues or defects within the software. This phase, also known as the verification phase, usually necessitates a repeat of the coding phase to address any bugs that are found. Occasionally this phase also involves the customer, allowing them to test the product to ensure that all requirements have been appropriately met.
After testing has been completed, the application is ready to be released. This final phase often consists of ongoing support by keeping the application current and functional, as well as addressing any bugs or errors when they are found.
Waterfall vs. agile
The two main distinctions between waterfall and agile methods are customer involvement and linear action. When using the waterfall method, each phase has to be completed before the next phase can be started. In an agile model, the functions of testing and development occur simultaneously. Additionally, the agile methodology encourages communication between testers, managers, developers and customers throughout the development process, whereas the waterfall method collects customer requirements at the beginning of the project and then limits their involvement from thereon.
When utilizing an agile methodology, the project is planned in “sprints” rather than milestones. Tasks are prioritized and completed in short periods, often in two-week intervals. Rather than outlining the phases during the requirements stage, all tasks are flexible within this model and are completed based on different variables, such as customer feedback and the success of preceding sprints.
Advantages of the waterfall methodology
Though its prevalence has waned over the years, waterfall methods can still provide many benefits to a project’s development process. This is especially true for larger organizations or projects that need stringent deadlines and stages to guide them. Here are a few of the other advantages of using the waterfall methodology:
It is easy to implement and manage because it outlines clear expectations and deliverables for each phase.
Because of the lack of customer involvement and the addition of new requirements, waterfall methods can be more efficient, expediting the process and ensuring faster project completion.
The detailed scope and requirements that waterfall provides allow for seamless adaptation even when teams and responsibilities shift.
Discipline and organization are enforced for the project as well as the team developing it.
It is ideal for organizations and teams that need a data and milestone-focused structure.
Because the project schedule is detailed at the project’s onset, it allows for a more accurate estimation of deadlines, resources required and project budget.
Progress is easily measured.
Limitations of the waterfall methodology
Though there are many benefits to using the waterfall method, changes in development and technology have proven the agile method to be more advantageous in most situations. Here are a few of the challenges you may face when using the waterfall methodology:
Because testing is done at the end of the project, it increases the likelihood that defects will be found and that they will be considerably more expensive to fix.
It is ineffective if there is a lack of clear requirements. This happens frequently because of the difficulty that most customers have when articulating their desired outcomes.
The absence of customer involvement throughout the project can result in a dissatisfied client upon completion when it is much more expensive to revisit the design and implementation.
Its rigidity makes it difficult to adapt to unexpected delays and events.