This article describes the installation of a water quality early warning system (EWS) at the Laredo (Texas) Jefferson Water Treatment Plant. The system provides protection of critical national infrastructure, specifically water and infrastructure at the treatment plant, with the designed purpose of protecting the plant against accidental and intentional contamination by harmful materials and pollutants. It also provides protection to water customers by evaluating water distributed from the plant for potentially harmful contamination or toxins. The article provides an overview of the following topics: system concepts and principles; EWS functions; building blocks of the EWS including cameras, radio frequency identification (RFID), water quality sensors, and SIG controller; data consolidation and transmission; integrated data‐monitoring platform; post‐action review; baseline facility and process analysis; other uses of an EWS; and, extended sensor complements in the future.