The U.S. Environmental Protection Agency (U.S. EPA), Office of Water, Municipal Facilities Division, has conducted a study examining the potential nationwide impacts of exfiltration from municipal sewers (exfiltration is the passage of wastewater or liquid wastes from inside sewerage systems, through defective joints, and broken and cracked pipe and manholes; the converse of infiltration). The study was conducted to determine: if sewer exfiltration occurs; if so, to what extent it occurs nationally; the potential impacts to groundwater quality; and finally what potential human health risks may exist.