ABSTRACT
Pathogens normally arise from contamination of water resources, although pathogens can contaminate water during treatment, distribution and within the home plumbing system ( Gray, 2008 ). Bacterial growth can occur on any surface that is constantly wet, and so the internal surface of water distribution pipes is normally coated with biofi lm. Among the major genera of bacteria associated with such growths and that readily multiply in water mains are Acinebacter , Aeromonas , Listera , Flavobacterium , Mycobacterium , Pseudomonas and Pleiomonas . The biofi lm protects bacteria from the effects of disinfection and these organisms, along with other heterotrophic bacteria, can cause illness. Currently, Legionella and Mycobacterium avium complex (MAC) are causing greatest concern in terms of public health risks. Water supplies are also vulnerable to deliberate interference or terrorist attacks, and there has been signifi cant work done in recent years to increase the security of supplies ( Rotz et al. , 2002 ) (Section 23.4.2).
