U.S. Environmental Protection Agency
Advanced Technology for Onsite Treatment of Wastewater, Products Approved by State - US EPA
https://www.epa.gov/septic/advanced-technology-onsite-treatment-wastewater-products-approved-state
The American National Standard Institute accredits GCT, LLC.
Wastewater Treatment Plant Certification Program
http://www.anab.ansi.org
EPA Office of Wastewater Management
OWM Oversees a wide range of programs contributing to the well-being of the nation's waters and watersheds
http://www.epa.gov/OWM
EPA's Wastewater Primer
Provides information OWM programs
http://www.tnrcc.state.tx/enforcement/ics/ossf.html
Louisiana Office of Public Health
Onsite Wastewater Program
http://www.oph.dhh.state.la.us/sanitarianservices/wastewater
Sewer Treatment Definitions
http://water.me.vccs.edu/stdef.htm
Texas Commission on Environmental Quality
http://www.tnrcc.state.tx/enforcement/ics/ossf.html
Mississippi State Department of Health
http://www.msdh.state.ms.us/msdhsite/index.cfm/30,0,78,0,html