ASSE Legionella Assessment and Management for Plumbing Systems (LAMPS) Practice Exam 2026 - Free Plumbing Systems Practice Questions and Study Guide

To ensure that a sample is collected specifically from the hot water tank rather than the cold water supply, it is essential to close the valve on the cold water supply. This action prevents any cold water from entering the sample, thus isolating the hot water system. By managing the flow in this way, the sample obtained will accurately reflect the conditions and potential contaminants present in the hot water tank, which is critical for assessing the risk of Legionella growth.

Other approaches, such as flushing the cold water supply first or opening the cold water valve, do not effectively guarantee that the sample comes from the desired source. These methods could introduce cold water into the sample or fail to sufficiently isolate the hot water system, which could compromise the integrity of the sample. Using a special sampling tool, while potentially useful for other purposes, does not address the need to manage the water flow effectively to avoid contamination from the cold water supply.