Sustainability in water quantity must imply sustainability in water quality. The human-induced loss of groundwater quality is a pervasive problem in both developed and developing nations. In the United States, extensive areas have groundwater within shallow surficial [superficial] materials, which may consist of unconsolidated deposits and/or weathered, porous, or fractured rock. These materials can reach depths of a few hundred meters and often lie above deeper bedrock aquifers. Groundwater in these surficial materials is particularly vulnerable to contamination as a result of actions or omissions of individuals and corporations (Fig. 20). These actions or omissions include inappropriate land use, overuse, negligence, attrition or obsolence, and accidents. The contamination can affect agricultural areas as well as other rural areas; in some instances, even urban areas are affected.