Bacteria such as E.coli (shown above) are naturally present in domestic water systems and at low levels have no adverse health or system implications. Problems occur when the correct conditions exist for the bacteria to proliferate such as within an ice machine. These conditions involve favourable temperatures, nutrient availability, stagnation and bio film build up. Bio film is a very thin bacteriological film that forms on the inside of pipe work and ice storage vessels. It is this bio film that supports and protects bacteria once they have colonised the system.