Who is allowed to test a backflow assembly

The person who may test a backflow prevention assembly is decided by the state drinking-water or licensing agency, and often by the water supplier on top of that. The U.S. Environmental Protection Agency delegates public-water-system enforcement to states and tribes that qualify for primacy. A 2025 EPA report to Congress says all states and territories have that primacy except Wyoming and the District of Columbia, where the EPA regional office implements the program. None of those federal pages creates a national backflow-tester license. If someone tells you a federal card is enough everywhere, that claim is not supported by the EPA primacy materials.

States that issue the credential

Texas is a clear licensing state. The Texas Commission on Environmental Quality says a person who repairs or tests the installation or operation of a backflow prevention assembly must hold a TCEQ license. The Backflow Prevention Assembly Tester license covers domestic, commercial, industrial, and irrigation services. Fire-line testing and repair are narrower: the tester must be permanently employed by an Approved Fireline Contractor.

Oregon’s Drinking Water Services issues its own tester card. Tester certification is required to test assemblies, except that an Oregon licensed plumber or journeyman is not required to hold it. The Authority still says the card is strongly encouraged because many water systems will not take a report without it. Testing for a fee also requires a Construction Contractors Board or Landscape Contractors Board license.

South Carolina says it is the certifying agency and that an out-of-state class does not replace its exam. Tennessee requires a Certificate of Competency in Testing and Evaluating Backflow Preventers. Mississippi licenses Certified Testers. These are examples. Use the state page for the property.

States that name an outside organization

Some states do not print the card themselves. They say which organization’s certification a water supplier may accept.

Arizona’s Department of Environmental Quality says tester certifications come from an ADEQ-approved authority. The page names the California-Nevada Section of the American Water Works Association, the American Backflow Prevention Association, the American Society of Sanitary Engineering affiliated with IAPMO, and All American Backflow Prevention. Those names appear because the state page lists them. They are not a universal national list.

Nevada’s cross-connection guidance quotes a rule defining a certified tester as a person certified by the California-Nevada Section of AWWA, by ABPA, or by an equivalent organization the Division approves. The Division says it does not keep the tester list. Missouri requires written and hands-on exams from ABPA or ASSE, including Missouri-rule questions, and notice to the Department of Natural Resources. Michigan will not accept ASSE 5110 alone. EGLE’s credential FAQ says the tester must also be a master plumber, a journey plumber, or an apprentice under the direct supervision of a journey or master plumber.

California’s State Water Board requires testers and specialists used for the Cross-Connection Control Policy Handbook to be certified by a recognized organization. From July 1, 2026, through June 30, 2027, that means an organization recognized in California. Beginning July 1, 2027, the organization must be accredited by ANSI to ISO/IEC 17024. The Board page is about the certifying body, not a do-it-yourself method.

When the water supplier decides

Other state pages require a cross-connection program and do not issue a tester license. Florida’s Department of Environmental Protection requires community systems to keep a written program and to eliminate a prohibited cross-connection or stop service. It does not, on that program page, name a state tester card. Pennsylvania’s public-water-supply manual tells the supplier to build the program when the Department directs it. Kansas statutes require protection and, for many irrigation systems, a testable double check, but they do not create a state tester roster. In those places the honest answer is: ask the water supplier who may sign the report. A card from a neighboring state is not automatically accepted.

What to ask for

Ask for the credential the state page names, then ask the water supplier whether it will accept that person for your assembly. A plumber license, a water-operator license, and a backflow-tester credential are often different. Ohio separates them in another way: the Division of Industrial Compliance certifies technicians for isolation devices inside buildings, and it says that certification does not apply to containment devices that protect the public system. How to verify a tester is the next step after you know which credential applies. Tester and cross-connection specialist explains why the person who administers the water system’s program may not be the person who tests your assembly.