The Life Cycle Assessment of Residential Onsite Wastewater Treatment Systems in Ontario

In Ontario, 1 million people rely on residential septic systems to treat their wastewater. The goal of the life cycle assessment (LCA) model is identify environmental hotspots of each of the five septic systems regulated under the Ontario Building Code. In the primary model, the Conventional Leaching Bed has the largest environmental burden in all ten midpoint impact categories. Overall, manufacturing and transportation contributed to majority of the environmental impacts. A sensitivity analysis showed that the native percolation time (T-time) of the soil is an important environmental consideration. The model was also tested for robustness by conducting four additional European-based life cycle impact assessments. The Conventional Leaching Bed had the largest environmental impacts in most midpoint impact categories, regardless of variation between units, while the Shallow Buried Trench or Sand Filter Bed typically had the least environmental impacts compared to the other three systems.