How do Agile approaches to systems development differ from those based on the waterfall model?

When to Use Agile vs. Waterfall

Agile and Waterfall are two popular methods for organizing projects. Waterfall is a more traditional approach to project management, involving a linear flow. Agile, on the other hand, embraces an iterative process. 

Waterfall is best for projects with concrete timelines and well-defined deliverables. If your major project constraints are well understood and documented, Waterfall is likely the best approach. 

In the ever-expanding world of project management approaches and frameworks two of the heaviest hitters are Agile and Waterfall.

The important thing to remember about both Agile and Waterfall is neither are technically a project management methodology. Instead, Agile can be defined as a mindset to approaching projects which provides flexibility, while Waterfall offers a pre-defined framework to follow that is sequential in nature.

What is the difference?

Agile includes a set of principles and values that came to life in 2001, created by 17 technology leaders. Underneath the umbrella of Agile are a range of frameworks and product delivery methods, such as Scrum, Lean, Six Sigma, and Kanban. Agile frameworks and methods do not generally manage the project lifecycle, rather provide a flexible and iterative solution, which allow you to adapt as the situation demands.

Want to learn more? Check out our guide, Agile: Everything You Need to Know.

Waterfall, on the other hand, is much more linear, focusing on up front planning with requirements fully defined before a project commences. Like its name suggests, work cascades, much like a waterfall, through different project phases. Each phase needs to be completed before the next one can begin.

“In Waterfall, members of a team work on their part of a project sequentially: define, design, build, test, deploy and maintain. Practices used by teams working in a more Agile way lead away from Waterfall in aim of better flow, more teamwork, and a greater focus on business value. Together, Agile team members focus on delivering outcomes rather than individually delivering a single pre-defined component of a project.”

Melinda Harrington, Enterprise Agile Coach at Woolworths Group

Agile pros and cons

Agile pros:

• Agile’s flexibility avoids rigidity. Stakeholders and team members have opportunities to observe and test throughout the project which allows for adjustments and changes to be made as things move forward. This greater ‘user focus’ means that on delivery it’s likely the outcome will be more in line with expectations – even if they have evolved along the way.
• Agile encourages teamwork, collaboration, self-organisation and accountability. This helps with overall motivation and commitment to a project’s outcomes and goals.

Agile cons:

• Because of its flexibility, an Agile project can run the risk of causing problems in other areas of the organisation as priorities shift if the changes are not managed and communicated effectively.
• For teams new to working in an Agile way, there is a risk that people can feel unsure of what they should focus on when the scope is developing.

Waterfall pros and cons

Waterfall pros:

• Waterfall is particularly efficient for well-defined projects. Project stakeholders agree upfront on what will be delivered, which makes planning and design much easier. Progress is more easily tracked as the full scope of the project is known from the beginning.
• Unlike Agile, this more linear approach often means that team members only need to be available for their specific project phases and can thus continue to focus in other areas. Equally a project’s customers may only need to be involved heavily in the early initial scoping phase and then at delivery.

Waterfall cons:

• On the downside, Waterfall requires comprehensive requirements up front which can sometimes be challenging for more complex or longer-term projects.
• Its sequential nature and reliance on pre-planning means there is a certain rigidity built into the project that makes mid-project pivots or directional shifts difficult to deploy without re-engineering all those pre-made plans.

How to choose?

As always, choosing which approach (Agile or Waterfall) is right for your project is entirely dependent on the nature of the project you have in mind and the culture and type of organisation you work for. Of course, the reality might be that a hybrid Agile Waterfall approach makes the most sense for your project but there are some general rules of thumb.

Agile

Agile makes sense where a project is based on incremental progress, complex deliverables or consists of multiple, not always sequential timelines. Projects that require cohesive and collaborative but cross-functional teams to deliver will need to take an Agile approach. If processes or roles are unclear it makes room for figuring it out as the project goes along. It also allows for involving the project client at any stage along the way. Products that are developed in stages, updates or versions are particularly suited to Agile.

Waterfall

Waterfall is usually more suited to less complex projects or those that have well defined requirements, processes and roles for team members. Single delivery timeframes with lots of detail and an expectation that very little is likely to change along the way are ideal. Waterfall also works well when the client is not required to be heavily involved beyond the initial brief and final delivery. From a management point of view, Waterfall can often make sense for fixed-price or contract dependent projects in order to lessen the risk of budget or delivery over-runs.

Decide before you start

So take the time to consider the best way forward before you get underway. Know your project goals and determine the variables, dependencies and activities that are crucial for your project. Identify the metrics and success factors that are most critical and review each approach for the best match. Engage your team in the decision-making process and assess their familiarity and experience with different project management approaches and frameworks. Finally, whatever choice you make, stick to it! Changing horse mid-race rarely ends well.

Did you know here at the Australian Institute of Project Management, you can gain recognition for a completed certification which includes some Agile credentials? Find out how you can be automatically granted the AIPM Certified Practising Project Practitioner (CPPP) level of RegPM.