Legionella bacteria is a dangerous microorganism that causes pneumonia and other respiratory problems. It is found in water sources such as air-conditioning units, hot-water systems, pools and fountains. It propagates through water, so if water is standing around for long periods of time, it can create a breeding ground for Legionella bacteria. Legionella causes serious respiratory problems and is a potential threat to human health. Here are some facts about Legionella and how you can keep your water areas safe with cleaning products on chlorine basis.