What is waterfall methodology?

“Standing still is getting behind.” – Arie van Bennekum

The waterfall method is one of those terms, that most people have already heard of in project management. It often falls, when a project manager needs to decide on which approach to use with his or her team.

But what exactly is the waterfall methodology? Simply put, it is a special way to manage projects of any kind. In contrast to other management methods though this is a linear and sequential process.

Before the beginning of a new project using the waterfall methodology several discrete phases are created. All the phases have to be completed one after another – a new phase can only begin, once the previous one has been completed.

Another special feature is, that a phases completion is absolutely terminal. This means, that no phase can be revisited, once it has been completed. If you want to return to an earlier phase, you will have to go all the way back to phase one and start over.
The different phases of a project using the waterfall method can be summed up to:

• Documentation and requirement gathering
• Design
• Implementation
• Testing
• Delivery and Deployment
• Maintenance

In the following we will go into detail in each phase.

What is waterfall methodology? – The different Phases

1. Gathering the requirements and documentation
   In the first phase all necessary information on the future project need to be gathered. This can be done in different ways which depend on the kind of project that is being planned – interviews, brainstorming and questionnaires are just an example. By the end of the first phase, all the requirements should be clear and documented.
2. Design
   In this phase of the project, the goal is designed. This could be a new product for example such as a computer program or a new soft drink. The design only takes place theoretically though with a focus on meeting all the requirements set in the first phase.
3. Implementation
   In the third stage of what the waterfall methodology is all about the team starts to actually create something out of the previous designs. Here a functional product is being made.
4. Testing
   Once a functional product has been created, it has to be tested. This can be done in various different ways and always depends on the product itself. A new car for example would now go to a special testing facility, whilst a new soft drink would be given to members of the public for a tasting. Any issues that arise in this phase may lead to the entire project having to return to phase one.
5. Delivery and Deployment
   Once the product has been completed, it can be made available to the public or any interested buyers.
6. Maintenance
   Whilst customers are using the newly available product, new and unforeseen problems may arise. These will have to be handled by the team in the maintenance phase.

Advantages and disadvantages of the waterfall methodology

According to a questionnaire, around one quarter of all manufacturing companies worldwide currently use the waterfall methodology method. So what makes all those companies follow this method?

First, one of the cornerstones of the waterfall methodology is the thorough documentation of every single little step. This way, new team members are able to easily understand their teammates and predecessors’ lines of thought and get right to it. Second, it is easy to see progress. In the first phase of any project the entire team has to set goals and a schedule. This makes progress measurable. Finally, this method is simple to follow. Every phase is clearly separated from the others and easy to understand. This way no team member can get sidetracked.

The linear procedure of the waterfall methodology makes it one of the easiest methods for project management. However, in this linearity also lies its biggest disadvantages. The waterfall methodology is not good at accommodating changes. If the requirements set in phase one change after it was already moved on to subsequent phases, it is very difficult to go back and make changes. Furthermore, the waterfall methodology is not suitable for complex, large size projects. Finally, the testing phase only starts when the implementation phase is finished. Thus, there is a high probability of problems in the design being only found when the implementation is already finalized. Arising problems are then often difficult and expensive to fix.

Here comes the agile method into play. As the name already suggests, with the agile method, companies remain flexible to makes changes even if a phase is already completed. This allows them to quickly adapt to not only changing project development requirement but also to the constant and rapid changes resulting from today’s connected societies and economies.

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