What two factors are used to determine groundwater contamination potential from septic tanks?

The correct answer highlights the importance of soil characteristics and depth to groundwater when assessing the potential for groundwater contamination from septic tanks.

Soil characteristics play a critical role in determining how effectively the soil can filter and attenuate contaminants that may leach from the septic system. Different soil types have varying capacities for absorption and retention of pollutants, which means that the specific attributes of the soil—such as texture, structure, and permeability—significantly influence how quickly and thoroughly contaminants can be removed before reaching the groundwater.

Depth to groundwater is equally vital, as a shallower groundwater table presents a higher risk of contamination. The closer groundwater is to the surface, the less time there is for natural filtration processes to occur in the soil before any potential contaminants enter the aquifer.

Together, these two factors—soil characteristics and depth to groundwater—provide a comprehensive understanding of the potential for septic system-related contaminants to affect groundwater quality, guiding decisions about the placement and management of septic systems to minimize environmental harm.