Does holding time, the time it takes to ship and plate water samples for Legionella, impact the accuracy of test results? Can Legionella growth vary so much that culture results are unreliable?

A study published in October’s Water Research has debunked these notions. In Effects of holding time and measurement error on culturing Legionella in environmental water samples researchers (Flanders, et al.) found that such assertions result from not factoring in measurement of error. 

Measurement of error or measure of uncertainty, a basic scientific principle, provides a statistical range for variation that can occur during ordinary laboratory processes. This ensures that with all microbiological procedures a standard deviation or standard error is factored into test results. 

Researchers found that when taking measurement of error into account, holding time had no practical impact on the interpretation of results. In short, there is no race against time. Be assured that shipping your water samples overnight will give you reliable results.