The purpose of the Backflow Assembly Tester (BAT) certification
program is to protect the health of the citizens of the state of
Washington. To protect health, state drinking water rules require
public water systems to develop and implement Cross-Connection Control
programs. Under these programs, some water system customers (property
owners) may have to install backflow prevention assemblies. Backflow
assemblies must get tested (when installed and annually after that) to
make sure they work properly.
Washington State Department of Health (DOH)
regulations require anyone who inspects, field tests,
maintains and repairs backflow prevention assemblies,
devices, and air gaps that protect the public water system
to pass the state's certification examination and maintain a
What is backflow?
Backflow occurs when water or other
substances flow in the opposite direction than intended
allowing contaminants to enter the public water system or
What is a backflow incident?
A backflow incident occurs when biological,
chemical, or physical contaminants enter the drinking water
supply (under backflow conditions) via unprotected
cross-connections. Backflow incidents may cause injury,
illness, or death.
What are backflow prevention assemblies?
Backflow prevention assemblies are mechanical devices
installed on water service lines (or at plumbing fixtures) to prevent
backflow of contaminants into drinking water through