{"id":32026,"date":"2026-11-06T13:26:01","date_gmt":"2026-11-06T13:26:01","guid":{"rendered":"https:\/\/www.tekrevol.com\/blogs\/?p=32026"},"modified":"2026-11-06T13:26:43","modified_gmt":"2026-11-06T13:26:43","slug":"waterfall-model-in-software-development","status":"publish","type":"post","link":"https:\/\/www.tekrevol.com\/blogs\/waterfall-model-in-software-development\/","title":{"rendered":"Waterfall Model in Software Development: How It Works"},"content":{"rendered":"

The waterfall model is a way to run a software project in fixed phases, where each phase is finished and signed off before the next one begins. It is also called the waterfall methodology, and it is one of the oldest ways to organize software work. This guide explains how it works and gives a simple test for when it fits a custom software development<\/a> project.<\/p>\n

How the waterfall model works in software engineering<\/strong><\/h2>\n

In software engineering, the waterfall model is a sequence of phases that each run once, in order. Requirements come first, then design, development, testing, deployment, and maintenance, and work moves back only when something goes wrong.<\/p>\n

The model is a way of sequencing the software development life cycle<\/a>, not a different process. The waterfall SDLC model keeps the same phases as any other approach and runs each of them one time.<\/p>\n

Teams still choose it when the scope is fixed, and a mistake is expensive. In our judgment, that is why it survives in regulated and contract-driven projects.<\/p>\n

Where the waterfall model came from<\/strong><\/h2>\n

The waterfall model is usually traced to Winston Royce’s 1970 paper, and Royce did not recommend the single-pass version of the approach. His paper, Managing the Development of Large Software Systems<\/a>, never uses the word waterfall.<\/p>\n

Royce described a sequence that ran from requirements through design and coding to testing and operations. He called it risky for large systems, because testing came last and a failure found that late usually forced a major redesign.<\/p>\n

He still called the basic approach fundamentally sound, and he proposed five safeguards: design first, document the design, build a pilot, plan the testing, and involve the customer. Later descriptions often kept the sequence and dropped the safeguards, which is TekRevol’s reading of how the model is usually taught.<\/p>\n

Phases of the waterfall SDLC<\/strong><\/h2>\n

Waterfall delivery runs through six phases, and each one ends with a sign-off before the next begins. In TekRevol’s reading of common guides, the stage count runs between five and eight, depending on whether they split out planning or retirement. We use six and fold planning into requirements.<\/p>\n

\"Waterfall<\/p>\n\n\n\n\n\n\n\n\n\n
Phase<\/strong><\/td>\nMain output<\/strong><\/td>\nUsually owned by<\/strong><\/td>\nSign-off test<\/strong><\/td>\n<\/tr>\n
Requirements<\/strong><\/td>\nSigned requirements document<\/td>\nBusiness analyst and client<\/td>\nCan every requirement be tested?<\/td>\n<\/tr>\n
Design<\/strong><\/td>\nArchitecture and interface specification<\/td>\nArchitects and designers<\/td>\nCan a developer build from this without asking questions?<\/td>\n<\/tr>\n
Development<\/strong><\/td>\nWorking code<\/td>\nEngineers<\/td>\nDoes the code match the specification?<\/td>\n<\/tr>\n
Testing<\/strong><\/td>\nTest report and defect log<\/td>\nQA team<\/td>\nDoes every requirement have a passing test?<\/td>\n<\/tr>\n
Deployment<\/strong><\/td>\nLive release and handover<\/td>\nEngineering and operations<\/td>\nIs the software running in production and accepted?<\/td>\n<\/tr>\n
Maintenance<\/strong><\/td>\nFixes and updates<\/td>\nEngineering and support<\/td>\nAre issues resolved within the agreed support terms?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

The owners and sign-off tests are TekRevol’s reading of common practice, because projects name them differently. The gate is what makes the model waterfall: if the test fails, the phase is not finished, and the next phase does not start.<\/p>\n

A waterfall example: an invoicing portal and one late change<\/strong><\/h2>\n

TekRevol’s illustration: a distribution company asks for an invoicing portal and signs a requirements document that says every invoice needs one approval from finance. The rest of the project is built on that document.<\/p>\n

In the testing phase, the finance team says large invoices need a second approval. That is a change to a signed requirement, so it goes through change control.<\/p>\n

Change control in a waterfall project is a formal request that states what changes and what it costs. Here, the request reopens the requirements, the design of the approval screens, the code already built, and the tests already passed, and the team quotes a new price and date before work resumes.<\/p>\n

The same change in the requirements phase would have cost a conversation. Found in testing, it costs rework in four places, and in TekRevol’s judgment, that gap is why waterfall projects spend so long on requirements.<\/p>\n

Advantages of the waterfall model<\/strong><\/h2>\n

The main advantage of the waterfall delivery model is predictability: the scope and the price are agreed before the build starts. Every benefit below depends on the requirements staying put:<\/p>\n