The Effect of Septic Systems on Wastewater-Based Epidemiology

For a wastewater intelligence program to be equitable, it should sample wastewater from sites that equitably represent the broader population, including an appropriate mix of rural and urban communities (Medina 2022). Like other public health services, wastewater analytics is more resource-efficient in urban areas. Rural populations are generally less dense and served by smaller wastewater treatment facilities (CRS 2016), so wastewater monitoring programs must devote more resources to cover the same number of people, compared to urban areas. Thus, special attention is required to ensure that wastewater intelligence programs adequately cover rural communities (Keshaviah 2022). 

Even when a community is included in a wastewater monitoring e program, that community may not be monitored evenly. Many homes, especially in rural areas, are not connected to a public sewer system and instead use septic systems or other waste management systems. This raises the concern that wastewater collected from municipal wastewater treatment plants will not evenly cover a community’s population because septic users are excluded (Holm 2022). 

In this white paper, we consider two hypotheses: first, that people who live in households with septic systems are not “covered” by wastewater monitoring programs; second, that the exclusion of people with septic systems introduces an undesirable bias into the results of wastewater monitoring