Legionella bacteria thrive in what type of water conditions?

Legionella bacteria thrive in warm, stagnant water conditions. The optimal temperature range for the growth of Legionella is typically between 77°F and 113°F (25°C to 45°C), which provides an ideal environment for the bacteria to multiply. Stagnant water, where there is little to no movement, allows the bacteria to concentrate and establish larger populations. This can often occur in poorly maintained water systems, such as those with infrequent use or inadequate turnover, which fosters conditions suitable for Legionella proliferation.

In contrast, cold, still water does not provide the warm temperatures that promote Legionella growth, while hot, flowing water can prevent stagnation and reduce the risk of bacteria proliferation. Freezing water is also inhospitable to the bacteria, as extreme cold conditions halt their growth and reproduction. Therefore, the answer correctly identifies the specific water conditions that facilitate the thriving of Legionella.