American Backflow Prevention Association:
http://www.abpa.org/

 American Water Works Association:
http://www.awwa.org

 Ontario Water Works Association:
http://www.oww.org

 TREEO Backflow Advisory Committe:
http://www.doce.ufl.edu/treeo/advisory.htm

 Georgia Water & Pollution Control Association (G.W.P.C.A.):
http://www.gwpca.org/

 Colorado Backflow Prevention Association(C.B.P.A.):
http://www.backflow.org/
 

Other:

Les O'Brien's Backflow site:
http://www.mindspring.com/~loben/water.htm

Backflow Incidents:
http://www.doce.ufl.edu/treeo/casehist.htm

Backflow Prevention Parts Suppliers:
Bavco
http://www.bavco.com/