Legionella bacterium is water-based organism that can cause a deadly infection called Legionnaire’s Disease if inhaled. Legionella Pneumophila (Legionella bacterium) is known to prosper in environments where standing water is present, such as tanks, reservoirs and areas of piping systems with poor flow. But what many don’t know is that scale and biofilm can form in these water systems and create a prime breeding ground to host and feed Legionella bacterium.