Pathogen sources
A sewage treatment plant
Most of the pathogens commonly found in water are enteric in origin.
Enteric pathogens are excreted with faecal matter from humans and animals. Pathogenic organisms enter water through contamination by human faecal waste and sewage, or from animal faecal waste.
Viruses shed in faeces of infected individuals are spread by the faecal-oral route.
Cattle farming in the catchments
Cryptosporidium oocyst contamination is widespread in the environment. It is found in cattle and sheep, particularly young animals, and in human waste. Waterbourne outbreaks of giardiasis around the world, caused by the Giardia protozoa, have generally been linked to consumption of untreated or unfiltered surface water and contamination by human waste.
Bacteria such as thermotolerant coliforms, including Escherichia coli (E. coli), are always present in high numbers in human and animal faeces. When found in water testing, they are generally regarded as specific indicators that the water has faecal contamination. Many thermotolerant coliforms are non-pathogenic but there are types of E. coli that can cause illness.
