A system and method for detecting a leak or structural defect in a tank are provided. The system includes a removable test plate to seal an opening in a tank to be tested with all other openings in the tank to be sealed. The system also includes a motor-driven blower or other vacuum-generating device coupled to a first opening in the test plate. When the blower is activated, it generates a vacuum inside the tank of a predetermined value. A vacuum-monitoring device is coupled to a second opening in the test plate and monitors the vacuum in the tank. A leak or structural defect in the tank is indicated if the vacuum decreases from the predetermined value by more than a predetermined differential within a predetermined time.