What is a limitation of relying on concentration (CFU/mL) in Legionella test results?

Relying on concentration (CFU/mL) in Legionella test results is limited primarily due to the variability in quantitation reported between different laboratories. This inconsistency can arise from differences in testing methodologies, equipment calibration, and interpretation of results. Each lab may have distinct protocols and standards, leading to scenarios where the same water sample tested at different laboratories yields different CFU/mL values. Therefore, decisions based solely on these results may not be reliable, affecting subsequent management strategies for Legionella risks in plumbing systems.

The other options do not accurately reflect the limitations of using concentration. Tests can provide important information about the presence of Legionella, and while high concentrations are critical to address, all concentration levels should be considered in a risk assessment. Additionally, the assertion that all test results are always consistent is incorrect; in reality, variations often occur, which underscores the importance of standardized testing methods and adherence to quality controls in laboratory settings.