Legionella testing

Legionella colonises warm water systems — cooling towers, calorifiers, spa pools, and the stagnant legs of building water distribution. Infection is by inhalation of aerosol rather than ingestion, which is why the risk concentrates around equipment that generates spray.

Its control is fundamentally an engineering matter: temperature regimes, flow, and the elimination of dead legs. Testing verifies that control rather than delivering it, and a positive result is read as evidence that the system, not the sample, needs attention.

Culture on buffered charcoal yeast extract with selective supplements remains the reference approach, and it is slow — up to ten days — because the organism is fastidious and slow-growing. PCR provides a much faster indication, but culture remains the method regulatory frameworks reference for confirmation.