The presence of Legionella in any water building water system presents a serious risk to human health. As a result there are strict guidelines for a testing regime for Legionella and other related organisms. The testing will confirm the absence or presence of Legionella in a water sample, and will also provide the serotype of the organism isolated. Although the legionella bacteria grows faster in warm water (especially around our body temperature), it can also be found cold water and industrial systems.