What is a primary function of a compression washer?

A compression washer plays a crucial role in maintaining the integrity of plumbing fixtures by serving as a seal that prevents leaks. When properly installed, it compresses and fills the gap between two surfaces, such as a valve body and its cover. This compression creates a watertight seal, which is essential in preventing water from escaping, thus ensuring that plumbing systems function effectively without unwanted water loss.

While securing the valve assembly, regulating flow, and controlling the opening or closing of a valve are important functions within plumbing, they are not the primary purpose of a compression washer. Its design and function specifically target the prevention of leaks, making this the most accurate choice in relation to the question.