http://www.zurn.com/ http://www.febcoonline.com/ http://www.wattsreg.com/ http://www.backflowtestkits.com/ American Society of Sanitary Engineering http://www.asse-plumbing.org/ American Water Works Association http://www.awwa.org/ Missouri Dept. of Natural Resources – Public Drinking Water http://www.dnr.mo.gov/env/wpp/dw-index.htm IAPMO Backflow Prevention Institute http://www.iapmodwbp.org/
