The following paper presents a computer-based learning strategy to assist in introducing and teaching water quality modelling to undergraduate civil engineering students. As part of the learning strategy, an interactive computer-based instructional (CBI) aid was specifically developed to assist students to set up, run and analyse the output from a commercially available water quality model (WQMAP) for a hypothetical raw sewage spill. The CBI aid comprised a Hypertext Markup Language (HTML) module with helpful text and still graphics, and links to on-screen recorded motion movie clips showing on-screen actions and voice narrations during the instructors absence. An anonymous class questionnaire to assess the students' perceptions of the developed approach found that most students felt they were able to complete the project with minimum supervision, and have acquired a basic understanding of water quality modelling as a result of the activity. Additionally, almost all of the students found the CBI aid helpful and easy to follow.