How did chemicals in wastewater get into the drinking water supply?
The shallow unconfined groundwater aquifer on Cape Cod is known to be vulnerable to contamination from wastewater. The majority (around 85%) of residences use septic systems to treat their wastewater. While some chemicals break down in septic systems, many don’t fully break down, so they are released into the groundwater. Discharges from centralized wastewater treatment plants are also released into groundwater. These discharges also can contain emerging contaminants. Once these chemicals end up in the groundwater, they can travel through the relatively porous sandy soils of the aquifer. The soils are relatively acidic and generally have low levels of organic matter. This means that chemicals won’t stick much to the soil particles (as they would if there was more organic matter), and there isn’t as much breakdown as there might be in other types of soils. As the Cape’s population continues to grow, this means there is more and more wastewater being discharged into the aquifer, and more
