Water Quality Awareness 101 3 | P a g e SECTION 1: GENERAL ADVICE 5. PATHOGENS The most common widespread and severe health risk associated with drinking water is contamination. This can occur directly or indirectly, from contact with human or animal excreta and the pathogenic (disease causing) micro-organisms contained within the faeces. Pathogenic organisms of concern include human infectious bacteria, viruses and protozoa. The diseases they cause vary in severity from mild gastroenteritis, through to severe and sometimes fatal diarrhoea or other types of infections. There are many pathways by which pathogens can enter the water supply but the most relevant ones to treated drinking water are cross connections, contamination events or poor hygiene within work practices. Every effort must be made to ensure that faecal material does not come into contact with drinking water Drinking (potable) water that has been cleaned and adequately treated should not contain any pathogens if the treatment systems are working effectively. Therefore the only way that water can become unsafe is if the barriers protecting the water are disrupted, allowing contaminant entry.