From The City of Heath:
Texas municipalities, including the City of Heath, are responsible for the enforcement and regulation of the Texas Commission on Environmental Quality (TCEQ) rules addressing the testing of backflow prevention assemblies on private property.
Backflow devices are typically attached to a landscape irrigation system, a fire sprinkler system installed in the home, a whole-house water treatment system, or other water uses. Ranging from simple to extremely complex, these units are a series of check valves that prevent water from flowing “backwards” into the clean water supply during times of unequal water pressure or other unique pressure conditions or fluctuations.
When installed and maintained correctly, a backflow device keeps the clean water supply safe. That’s why testing is so important. Residential homeowners who are on City sewer are required to have the backflow device tested every three years. Residential homeowners with septic systems and all commercial development must have the backflow device tested annually.