Contaminate Groundwater

 Contaminate Groundwater:

Groundwater not only contains the hydrogen and oxygen atoms that form water (H₂O), but it also contains naturally dissolved gases from the atmosphere and dissolved minerals and gases from the soil and rock through which it passes.
The soil filters the water and absorbs and removes many contaminants though some will pass through unimpeded.  But if the soil layer is thin, has high permeability, or if the water table is close to the land surface, then the soil is less likely to adequately treat contamination.  The excess contaminants may pass through the zone of aeration and enter the groundwater in the zone of saturation.