Which performance measurement is least beneficial for managing Legionella risk in a large building's domestic water system?

The least beneficial performance measurement for managing Legionella risk in a large building's domestic water system is the difference between the average cold water outlet temperature and the national average. This measurement does not provide actionable insight into the specific conditions of the building's system or how those conditions contribute to the potential for Legionella growth.

When focusing on Legionella management, it is essential to understand the specific temperatures within the building's system, particularly regarding the hot water system's temperatures, which should be consistently maintained above 60°C (140°F) to inhibit bacterial growth. Monitoring the overall temperature trends within the system and noting any discrepancies can directly inform maintenance needs and adjustment of system operations to mitigate risk.

Tracking overall hot water usage trends can also highlight patterns in water availability and how they might relate to temperature control and stagnation, both of which affect Legionella risk. Frequency of maintenance checks relates directly to keeping the system free from problems that can encourage conditions for Legionella growth. Thus, these parameters provide a more direct connection to managing risk than simply comparing averages to a national standard.