Which statement does NOT describe a disadvantage to an impressed cathodic protection system?

The statement regarding the requirement for the tank to be at least half filled with product at all times does not accurately describe a disadvantage of an impressed cathodic protection system. This is because, while certain types of cathodic protection systems may have specific operational considerations related to the medium being protected, the concept of filling a tank to a certain level is not universally applicable as a limitation of impressed current systems. Impressed cathodic protection works by applying a continuous electric current to the structure needing protection, relying on a rectifier and anodes; it is primarily influenced by factors such as the electrical conductivity of the surrounding medium rather than the product level within the tank itself.

Understanding the functioning of impressed cathodic protection involves recognizing that these systems rely on an external power source to deliver current, and are subject to various operational challenges, such as interference from stray currents and the necessity for regular monitoring and maintenance, which are represented in the other statements.