Why is it recommended to collect both pre-flush and post-flush samples from drinking fountains?

Collecting both pre-flush and post-flush samples from drinking fountains is particularly important in the context of Legionella management because many drinking fountains are rarely used. This infrequent usage can lead to stagnant water in the plumbing systems. Stagnation provides a conducive environment for Legionella bacteria to grow, as the water may become warm and nutrients can build up without regular flushing.

Pre-flush samples allow for the assessment of water quality before any fresh water is introduced, capturing the state of the water that has been sitting for an extended period. By contrast, post-flush samples reflect the quality of the water after it has been refreshed through flushing. Comparing these two sets of samples helps to identify whether stagnant water has contained elevated levels of Legionella, signaling the need for further action, such as increased maintenance or flushing protocols to ensure safe drinking water.

This thorough approach helps ensure that drinking fountains maintain water quality that aligns with safety standards, making it critical to understand the usage patterns of each unit.