Chest drainage systems operate on the principle of restoring negative intrapleural pressure by providing a one-way evacuation path for air and fluid. Modern disposable units integrate three chambers: the collection chamber measures output, the water-seal chamber prevents atmospheric air re-entry (acting as a one-way valve), and the suction control chamber (wet or dry) regulates applied negative pressure. Water-seal tidaling reflects respiratory pressure changes transmitted through the pleural space and confirms system patency. Air leak assessment is performed systematically by evaluating bubbling in the water-seal chamber: continuous bubbling indicates a persistent bronchopleural fistula or system breach. The nurse manages the entire chest drainage system, troubleshoots complications, interprets assessment findings, titrates suction, and determines readiness for tube removal.