Which contaminant source is most likely to affect groundwater quality?

Septic systems are significant potential sources of contamination for groundwater quality. They are designed to treat and dispose of household wastewater, which contains nutrients, pathogens, and organic material. If a septic system is improperly designed, installed, or maintained, it can lead to the release of contaminants into the surrounding soil and, ultimately, into the groundwater. This is particularly concerning in areas where the groundwater is used for drinking or irrigation.

In contrast, while urban landscaping can introduce contaminants through fertilizers and pesticides, the impact is generally localized and often mitigated through proper management practices. Weather patterns can influence groundwater levels and quality indirectly but are not a direct source of contamination. Natural mineral deposits can affect the mineral content of groundwater but are a natural occurrence and typically do not reflect anthropogenic contamination. Thus, septic systems represent a more direct and significant risk to groundwater quality.