Plumbing Tier 1 Practice Exam 2025 – Comprehensive All-in-One Guide for Success!

An expansion tank serves a crucial role in a plumbing system by absorbing excess pressure that arises due to thermal expansion of water. When water is heated, it expands, leading to increased pressure within the plumbing lines and hot water heaters. If this pressure is not managed, it can result in damage to pipes and fittings, as well as leaks or ruptures, creating significant plumbing issues.

The expansion tank is designed specifically to accommodate this necessary expansion. It typically contains a diaphragm or bladder that separates the air and water, allowing it to flex as the water expands. This absorption of thermal expansion protects the integrity of the plumbing system, ensuring that pressure levels remain within safe limits and preventing potential damage over time.

The other options mentioned relate to different aspects of plumbing systems. Providing additional hot water storage focuses on the function of a water heater, filtering impurities pertains to water quality management systems like filters or purifiers, and preventing backflow involves the use of devices like backflow preventers which are designed to stop contaminated water from reversing into the clean supply. Each of these functions serves important roles but does not address the specific need to manage pressure fluctuations resulting from water heating, which is the primary purpose of an expansion tank.