Pathogens are disease-causing agents, which can come in the form of bacteria, viruses, mould spores, or protozoans, and which are normally present in large numbers in sewage waste.
The nature and extent of potential pathogen risks of sewage backups and floodwaters will depend in large part on the potential contaminants expected to be in the waters. In general, the greater the extent of the sewage component, the more likely the potential for adverse impacts, and the more important the proper cleanup of the materials that have come into direct contact with the contaminated waters. The severity of the health threat therefore depends on the source of the water and the extent of penetration into the building environment. The extent of penetration is dependent on the porosity of contaminated materials, the quantity of floodwater, and the amount of time the water remains in contact with materials.
Even floodwater or stormwater which has not been directly impacted by sewage discharges is likely to contain a wide variety of microbiological organisms such as animal waste and street runoff and must be properly managed. Some of these pathogens, such as mould spores, can even establish an ecological niche and present a health risk from chronic exposure for some time after the event. Preventative measures and proper cleanup procedures are essential in mitigating the risk of infection.