Assessing the Effectiveness of PCAT in Avoiding Process Anomalies in Water Treatment Plants

Traditional anomaly detectors in water treatment and distribution plants identify process anomalies only after their impact has been realized, limiting their ability to prevent disruptions or damage. This paper introduces the Programmable Logic Controller (PLC) Command Validation Tool (PCAT), an anomaly-avoidance framework that verifies the correctness of control commands issued by PLCs before they reach actuators. PCAT was evaluated on the Secure Water Treatment (SWaT) testbed under realistic attack scenarios inspired by real-world incidents. The framework demonstrated the ability to raise alerts significantly earlier than existing methods—triggering one alert 2.5 seconds in advance—thereby effectively preventing anomalies before physical damage occurred. Over six hours of normal operation, PCAT recorded zero false positives, confirming its precision and reliability. These findings position PCAT as a proactive and effective solution for securing water treatment operations.