As wastewater moves through the soil, what happens to disease-causing organisms?

As wastewater moves through the soil, disease-causing organisms are treated, removed, or destroyed through various natural processes. The soil acts as a filtering medium. Microorganisms present in the soil, such as bacteria and protozoa, help to break down organic matter and pathogens, effectively reducing their concentration. Additionally, the physical filtration process of the soil can remove larger particles and debris, while chemical processes, such as adsorption and precipitation, contribute to the deactivation of harmful pathogens.

The combination of these biological, physical, and chemical mechanisms ensures that the majority of disease-causing organisms are significantly reduced before the effluent reaches groundwater or surface water bodies. This is crucial for preventing waterborne diseases and protecting public health, making the treatment capacity of the soil an essential aspect of on-site sewage management. However, it's important to note that while some organisms may be removed, others may remain viable under certain conditions, underscoring the need for proper design and maintenance of sewage systems to ensure effective treatment.