Project Management: Agile versus Waterfall explained in simple words

Project Management: Agile versus Waterfall explained in simple words

Since the term was coined in 2001 by the founders of the Agile Manifesto, Agile approaches have been taking over the project management scene at a steady pace. Some say Agile is a mindset not a methodology, others believe it is the silver bullet to solve any project management challenge, and doubters do not want to hear about Agile at all. We can witness a wide range of opinions while the exact attributes and applications of Agile and traditional project management approaches remain unclear for many.

With the numerous approaches and rich taxonomy including terms such as Waterfall, Lean, Agile, Scrum, XP, phases, Sprints, increments, and releases, it is easy to get lost in the ever-expanding project management terminology.

The web and specialised libraries are not short of technical papers elaborating on the various methodologies at length. This article ambitions to provide clarity on the key attributes and applications of Agile and Waterfall/Traditional methods using the simplest example possible.

This article will talk take you through the fictitious but realistic journey of a young couple. Before plonging in their intimate life, let us clarify part of the project management terminology.

As stated in the PMI Agile Practice Guide, Agile is a blanket term for many approaches as illustrated below:


We will refer to the generic term of Agile approach as we are not discussing a specific application such as Scrum or Extreme Programming (XP).

Now let’s see how our couple manages daily life projects and what valuable lessons we can retain from their adventures.


Waterfall in Practice

Donald and Melania are a freshly married couple who just managed to gather enough cash to acquire a small plot of land on which they are planning to build the house they will eventually call home.

Their dream still seems really far away. So many steps must be completed before they can eventually move in. The ground will be dug out, the foundations laid and levelled, the walls built, the electric cables pulled throughout the house, the windows installed, flooring, tiling, etc. Then, the interior will have to be meticulously designed, furnished, and tailored to the taste of our duo.

To tackle this herculean challenge, the young couple hires an architect called Denise who develops a detailed plan containing the most minute details and specific measures broken down to the millimeter for every single area of the house. The couple formally accepts the plan, and the architect provides them with a set schedule comprising dates corresponding to each milestone from the first day of digging until the last day on which they will finally receive the keys to their house.

The expected outcome of this work is crystal clear. Denise has built many similar houses before, and our couple knows what a house is supposed to look like as well as the functionalities of each room.

Architects should stick to the plan as far as the law of physics allow. Changes are mostly unwelcome. Melania and Donald would certainly not appreciate discovering that Denise decided to remove a room, or place the power sockets at 2 meters of height because it spared 12 meters of cable and made work easier for her staff.

Similarly, the architect would not appreciate if midway through the build our tandem requests walls to be made of wood rather than bricks.

There is also a clear sequence and order for the different steps that will take place. You need foundations before building walls, you need walls to carry ceilings, you need ceilings to hang lamps, etc.

In summary, the performance of the architect is mainly judged by the ability to deliver exactly what had been planned in terms of schedule, scope, and cost. If the couple receives the keys to a house that is identical to what was depicted in the promotional leaflet (which rarely happens) on the agreed upon date and without having to contribute one additional penny, they will be delighted and rightfully so.  


What is Waterfall Project Management

The type of projects that have a clear outcome using tested and proven technologies and techniques, usually follow traditional project management methodologies, mainly labelled as Waterfall (also named predictive or traditional methods). As indicated by its name, this type of approach divides projects in a waterfall sequence of phases. A phase usually ends before the next one starts, and the sequence is traditionally the following:

The Project Management Institute’s Project Management Body of Knowledge (PMBOK® Guide) defines each of these phases in great details.

In the case of our enamored couple, and put in (very) simple words, the phases are composed of the below key activities:

  • Initiation: Our couple (the Sponsor) is giving the authority to the architect (Project Manager) to manage the project by signing a project document (Project Charter) outlining, expectations in terms of scope, budget, schedule, and stakeholders.
  • Planning: Creating the technical drawings, 3D renders, detailed budget, and schedule that will enable the project’s realization.
  • Implementation: Carrying out the actual work necessary to build the house.
  • Controlling: Ensuring that the work being carried out is not deviating from the plans elaborated during the planning phase. For example, measuring that the walls are indeed 2.2 meters highs and that the paint applied is using the right color pantone.
  • Closing: Hurray! The house (project) is completed! Following a the snagging of the house, our duo will sign a document confirming the acceptance of the work (Certificate of Completion) and the architect will collect the lessons learned during the project to share with his teams to avoid repeating mistakes in the future.

The sequence of phases is chronological and only happens one time.

The couple only visited the building site 4 times during the build and the house was officially handed over on time to their greatest delight.

They could then focus on the furnishing and interior design of their home. For this project, they decide to hire Kelly a seasoned interior decorator who has done a great job with the house of Donald’s colleagues.


Agile in Practice

Our duo tells Kelly that they would like something similar to Donald’s colleague’s house. In particular, they express the wish to have the same bar around which they end up having their last drinks every time they visit. They agree on an overall look and feel and entrust Kelly to do miracles.

The work should be done by the time they come back from their extensive honeymoon.

Kelly worked hard and sure enough she delivered her promise, by the time they came back, the entire house interior was modelled to what she believed was the unique taste of our duo.

When the couple returned home from their lavish trip, they were horrified. The bar looked humongous in their living room, the style of the furniture was in total discord with the modern kitchen the architect had installed, the colors of the paint seemed brighter than the samples in the leaflet they had chosen them from, etc. The couple was fuming and the only reply they got to calm them down was, “but this is what you asked for guys”. Which in essence was true. Heated arguments started, and things ended ugly.

So why did the architecture project unfold so well while the interior design ended in an absolute catastrophe? Is the architect more skilled than the interior designer? Should the couple and the interior designer have spent more time planning? Were the drinks around the bar impairing Donald’s vision of his colleagues’ house? Likely, none of these suggestions is the right answer.

The main issue here is that the methodology used was not well-suited for the project type. Unlike with the building of the house, the expected outcome was unclear. Also, this was all very new for the couple. While they could easily comprehend that a room that is 40cm broad does not serve much purpose, they do not have the ability to judge without seeing it whether a 320cm by 195cm rug in a 5.2m by 6.1m room will fit well or not and which colour would be the best match without seeing the items beside each other. Doing this interior design work in one bulk was very risky and the risk did not pay off. They should have adopted a more Agile approach.

For those of you who had the chance of experiencing moving in as a couple, I am sure you have a great load of souvenirs of trial and error. Likely, you did not just do one round trip to IKEA, purchased all the needed furniture, and installed each item in the place you had assigned for it prior to the shopping session.

Chances are, you had (a little too) many trips to different stores, maybe returned some furniture you had purchased as it did not fit or match, adapted the design as you were advancing in the furnishing of your home, and who knows, maybe even had time to argue with your partner in the process. You took some decisions on the go, for example, you bought the light grey carpet because it matched the black sofa you ordered, you tried samples of paint directly on the wall to have a better idea of how the paint reflects the light in the room, and you probably placed the paintings on the wall last to be able to see where they best fit.

In project management, it is advised to use an incremental approach for such projects. Instead of planning and delivering one very large chunk of work at once, you elaborate progressively (by increments) and just like an artist you mold your masterpiece day by day, stroke by stroke. In this scenario, it is best to take decisions at the last possible moment when you benefit from the maximum information and observations. For example, you decide what carpet you will buy when you finished furnishing the living room, you purchase a console before choosing the mirror you will place on top of it, etc. instead of purchasing all the living room items at once.


What is Agile Project Management

Contrary to Waterfall methodologies where all tasks are planned, implemented, controlled, and eventually accepted all at once, in most Agile methodologies the project is a collection of short iterations of equal duration (usually 2-4 weeks) that are generally referred to as Sprints. So, smaller chunks of work are planned, implemented, and controlled many times throughout the project.  



These chunk of the project scope (Sprints) are then broken down even further into tasks (User Stories) that are prioritized based on value and risk. Throughout the Sprint, progress on these tasks is monitored through Daily Standup meetings. They are called Standup Meetings as their length should not exceed 15 minutes and they are often held while standing to ensure they are kept short. During these meetings, each team member shares what has been done the previous day, what will be done today, and what are the eventual roadblocks to the progress. 

At the end of the Sprint, the work completed is demonstrated during a Sprint Review in front of the client for feedback and/or acceptance. For example, painting the living room could have been a User Story included in the first Sprint and our couple could have approved it or requested for some changes such as a less glossy paint during the Sprint Review at the end of the Sprint. This drastically limits rework and the associated costs. Imagine if our duo decides to change the paint color once the entire house has been painted. Thus, Agile practitioners say it is good to fail fast. This allows to rectify the trajectory early in the process, before too much time, effort, and cost have been invested.

This type of approach allows for frequent feedback, changes to the initial plan, and drastically reduces misunderstandings with the client. The interior design is just an illustrative example for high-level understanding. Agile approaches are most commonly used to deliver IT projects.

Generally, IT projects can be broken down into small functionalities that do not need to follow a specific order. Contrary to the fixed order of tasks when building a house where you need walls to support a roof, when creating a website for example, you can work on the landing page visual, or the button customers will click to checkout independently in whatever order you prefer.

The priority of tasks in this case is determined by the value each task represents for the client (tasks with high risk are also prioritized). The higher the perceived value by the client is, the earlier it is implemented.

In the case of our couple, they would likely perceive more value in seeing the paint first rather than the silicon joints that will be used (despite the joints playing a more important role in the functionality of the house). So, paint would be included in the early Sprints before the work on the silicon joints.


Hybrid in Practice

Some projects require a hybrid approach.

Imagine the architect had been mandated to deliver both the house and the interior design. She would have used a Waterfall approach to build the house and an Agile one to complete the interior design. This is referred to as a Hybrid implementation.


What is Hybrid Project Management?

Hybrid projects are typically not industry-specific but rather apply to initiatives where the deliverables themselves are hybrid. For example, the construction of a new building that will host an equally new IT system or a large event that requires building structures before coordinating the event activities. In these cases, a Waterfall approach will be used for the building phase and an Agile one for the subsequent activities.


to use  


Imagine the architect had been mandated to deliver both the house and the interior design. She would have used a Waterfall approach to build the house and an Agile one to complete the interior design.


When to Use What?

It is key to understand that no approach is better than the other; they simply serve different purposes and contexts.

Waterfall is great for projects that have a very clear and well-defined outcome using existing technologies and proven techniques. It is very common in construction, infrastructure, and government programs. 

Agile can provide astounding results when dealing with uncertainty, unclear scopes, untested techniques, or simply clients who change their mind often (not to say who do not know what they want). Thus, it is extremely popular for software development, design projects, and events.

I often get the question:

 “How do I know when to use Waterfall and when to use Agile?”

I have heard a lot of Savvy answers to this question and seen many elaborate tools designed to identify the best-suited approach. However, I prefer using a dead simple approach: 

If your team is unsure of the answer to this question, go with waterfall.

While Agile can reap great rewards, it requires having a seasoned team that is not only knowledgeable but experienced in Agile projects. Else, the flexible approach of Agile can lead to absolute chaos.

A team that has the sufficient experience to carry out an Agile project knows when to use Agile.

If there are doubts, likely the team needs to gain some Agile experience and you can gradually introduce some concepts such as the daily meetings that have been recognized to increase Waterfall projects’ performance. Then, hire an Agile coach to train the team on Agile methodologies to gradually become more Agile.

Do not overlook the complexity of Agile, it is not learnt over night, it is a complex combination of mindset, ceremonies, artifacts, and tools that require sound project management experience.  

Feel free to contact us if you or your team wish to expand your understanding of the different approaches.


Karim Radwan

Founder of Impactus Consulting

Karim Radwan is a self-directed project management professional with extensive experience in both the private and the public sectors. Domains of work include, banking, FMCG, and development projects. Regardless of the industry, Karim witnessed high potential for improvement in project management methodologies, productivity enhancement and crisis management. His taste for entrepreneurship decided Karim to establish IMPACTUS Consulting in Dubai to help companies around the world adapt, innovate and prosper in shifting environments.

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