Waterfall method: an introduction guide for beginners

Before starting to manage a project, it is essential to define the methodology that will be followed. There is a wide variety of methods. From the more recent agile method to the older and traditional waterfall approach, you are spoilt for choice.

Here is a short guide to help you understand how the waterfall method works as well as its advantages and disadvantages.

Definition

The waterfall method, also called the “waterfall” methodology, consists in managing a project by following linear and sequential phases. Each phase is dedicated to specific tasks and depends on the results of the previous phase.

In the same way that the water that goes down a waterfall cannot go up, the project team cannot (or almost cannot) go back in the production process. After each stage is complete, you have to move on to the next without the possibility of going back. The project follows a specific direction and achieves its final objective by following each stage, one after the other.

Origin of the Waterfall methodology

In June 1956, Herbert D. Benington presented for the first time a phase model for software development. However, the first description of the waterfall model is attributed to Winston W. Royce in an article published in 1970. The term “waterfall” was first used in 1976, in an article by Bell and Thayer who credits Royce for the term (source: Wikipedia).

Thanks to its logical sequence and ease of implementation, the waterfall method is rapidly adopted by many industries, including the construction and development of computer software.

How does it work? What are the different phases?

The implementation of the cascading project management method follows a succession of six phases in a precise and strict linear order. According to the Waterfall model, a phase cannot start until the previous phase is over.

• Requirements : all the needs and requirements of the client are identified at the start of the project, which makes it possible to plan the following phases without the involvement of the customer until the project is delivered.
• Analysis : the team analyzes customer requests in order to define precise specifications.
• Conception : this phase consists of planning all the steps, tasks and sub-tasks necessary to carry out the project. This type of cascading project can easily be planned and monitored using a Gantt chart.
• Implementation : the team enters the product production phase by precisely following the customer's specifications.
• Validation : the team delivers the finished project to the customer who tests it and checks whether it meets all its requirements before validating it. If there are errors or problems, the team solves them according to the customer's requests for changes until the customer is completely satisfied with the project.
• Start-up : the finished product can finally be installed and used.

A phase only starts when the results of the previous phase are validated. No returns are possible unless a major problem has been discovered during the verification phase.

The project team works alone, carefully following the specifications defined during the first phase (requirements). The client no longer intervenes throughout the duration of the project until the validation phase. It is therefore essential that nothing is forgotten during the first phase.

Why choose the cascading method and when should you use it? Advantages and disadvantages in project management

Like all working methodologies, the waterfall approach has its pros and cons.

Benefits

If the objectives of your project are clearly identified, the waterfall method is perfectly suited because it is at the same time simple, easy to set up, logical and very structured. It is also ideal for projects where quality is more important than cost and time.

Since everything must be planned in advance, the cascade method allows you to have a precise idea of the budget necessary to carry out the project. It also makes it possible to accurately plan the time and resources necessary for the smooth running of the project. No phase overlaps and it is clear when the project will have to be delivered.

It is easier to measure the progress of the project with this method since the entire progress of the project is defined beforehand.

After the requirements phase, the presence of the customer is not necessary during the course of the project, which is convenient for customers who are not available.

Disadvantages

The main disadvantage of the waterfall method is its lack of flexibility. Since it takes place by following precise steps, it leaves no room for the unexpected, for changes and modifications.

With this approach, you are more likely to see your customer dissatisfied and disappointed with the final result of the project if effective communication was not put in place during the requirements phase. Indeed, since the client cannot intervene and will only see his project once completed, it is possible that it is not in line with his expectations and needs which may have evolved, as well as the context in which the project is located (new competitors, new technologies, new markets, etc.).

For any change, the team will have to review the entire project (or almost all) because all stages can potentially be affected. This discourages the consideration of possible changes and, above all, a change risks generating delays and additional costs. Indeed, it is less practical and more expensive to add an additional option on a project that is almost complete than on a project in progress.

Finally, this type of cascading method is not suitable for complex, large-scale projects.

Conclusion: waterfall method vs agile

The strict and rigorous organization of the cascade method is highly appreciated by some industries. However, today, the agile method is often preferred to the waterfall method because it offers greater flexibility and allows the customer to be involved throughout the project. However, it is entirely possible to create your own method by combining the agile method and the Waterfall approach.