The keys to avoidance of terrorist acts are first, deterrence, and second, early detection of something happening, detection in real time. The best way to know what's happening "outside" is to integrate video, audio, and data information through a SCADA (Supervisory Control and Data Acquisition) system, that has monitoring capabilities that can detect whether something out of the ordinary is happening or has just happened. By alarming and monitoring video, audio, and numeric data associated with every possible access point within a water or wastewater system, terrorist acts can be avoided before they occur. This paper outlines a systematic process to design a system that allows early detection of any incursion and allows for early response to avoid any kind of catastrophic event. The paper illustrates the process of developing a plan, including the cost and the technology available to avoid such occurrences. It also demonstrates the methods to balance what's probable and what's possible. Includes figure.