Public Drinking Water Branch

Backflow Prevention

What is backflow?

Backflow, or the reverse flow of contaminated water into a potable water distribution system, is caused by backsiphonage or backpressure.

Recommended Actions

How to become a certified backflow tester
Missouri Backflow Prevention Regulations
Basics of Missouri Backflow Regulations -- PUB393
Backflow Prevention Frequently Asked Questions -- PUB 2158
Missouri Backflow Prevention -- PUB2016

Approved Backflow Assembly List
Missouri bases its approved backflow prevention assemblies list on the approved assemblies list published by the University of Southern California’s Foundation for Cross-Connection Control and Hydraulic Research. Missouri only approves Double Check Valve Assemblies, Reduced Pressure Principle Assemblies, or approved Air Gap as containment devices. Therefore all other devices on the USC-approved list are not considered containment devices in accordance with 10 CSR 60-11.010 and 11.030. 
USC Approved Assemblies List

Backflow Prevention Assembly Testers

Backflow Assembly Test form 780-0804

Resources
American Society of Sanitary Engineering
American Backflow Prevention Association Tester Certification Information
Foundation for Cross-Connection Control and Hydraulic Research
U.S. Environmental Protection Agency Cross-Connection Manual
Drinking Water Security
EPA Backflow Prevention Devices