Tests that assess microbiological activity are often used by water treatment professionals who are looking for an efficient method to predict the presence of Legionella. Because standard Legionella culture takes at least three days for a preliminary result, many use tests such as adenosine triphosphate (ATP) and Heterotrophic Plate Count (HPC) as a substitute for culture.
ATP is a simple process that can be completed in less than and hour and is an alternative method of microbial population enumeration. Microbial culture methods like HPC provide effective quantification of planktonic microbial populations in water samples. But data comparing each of these methods in terms of accuracy for analysis of Legionella in potable and utility water samples are scarce.

So we asked the questions: Can ATP or HPC be used as a predictor for Legionella in potable and utility water? We also looked for Legionella to see what if any correlation existed.

Our purpose of study, in collaboration with the University of Pittsburgh, was to determine:

  1. Sensitivity and specificity of ATP results and correlation with HPC measurements.
  2. Correlation between ATP and HPC measurements and the presence of Legionella in both cooling and drinking water samples.