Inaccuracy in Legionella tests of building water systems due to sample holding time

► Sample holding time caused unpredictable changes in results in Legionella cultures. ► Results from two methods were not significantly different in standardized testing. ► Shipped water samples returned 9.5% false-positive and 1% false-negative results. ► Overall accuracy of results from shipped water samples was 89.6%. ► On-site inoculation of building water samples improves test result accuracy.