The Waterfall Model: No Going Back

Say a truck driver has to go from New York to California with multiple stops in between.

When he reaches California, suppose he missed a stop in Las Vegas, Nevada?  He would not be able to drive back to Nevada, but rather drive ALL the way back to New York and then continue onto Nevada.

The Waterfall model is not iterative, as in, it does not allow a return to previous steps.

Remember these three things for the CISSP exam in regards to the Waterfall Model:

  • The process is linear

  • It does not allow programmers to go back a step

  • It is does not work for complicated and detailed projects, maybe smaller projects

Dr. Winston Royce was the first to write about the software development waterfall model in 1970, and by write about it I mean he was the first to criticize it.

He reinforces that in the real world it is not realistic to prevent developers from going back a step.  The only time to really find out if the product works is in the final stage, when there would be no going back to any other part of the development stage.


You don’t need to memorize each step of the process below, but rather try to remember the overall process.

For example, you need to first come up with requirements for the system before coding it.  You need to code it before testing it.  You need to test it before deploying it to a production environment.

waterfall model