Missouri Backflow Certification
What Missouri Backflow Certification Requires
Backflow prevention in Missouri falls under the Department of Natural Resources (MDNR) Safe Drinking Water Commission, regulated by 10 CSR 60-11.010. Containment devices such as reduced pressure zone (RPZ) and double check valve assemblies must be inspected at installation and at least annually by a certified tester. Performing this work without the credential is illegal and puts public water supplies at risk of contamination.
Prerequisites Before You Apply
You need at least five years of documented experience in plumbing, pipefitting, or a related field such as lawn irrigation before you can sit for the certification exam. This is not a credential you can fast-track out of trade school — the prerequisite exists because field-testing backflow devices requires hands-on familiarity with pressure systems.
The 40-Hour Initial Course
The certification path starts with a 40-hour training program administered by an ASSE or ABPA-approved provider. Ranken Technical College in St. Louis is one of the primary providers in Missouri, with course fees running approximately $1,025 (non-refundable).
The course covers theory, device types, and hands-on testing of RPZ, double check (DC), pressure vacuum breaker (PVB), and spill-resistant vacuum breaker (SVB) assemblies. The final exam requires you to test each device type entirely from memory — no reference materials allowed during the practical portion.
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Exam Details
The certification exam includes both a written test and a hands-on practical. You must demonstrate that you can correctly test, diagnose, and report results for each assembly type under timed conditions. Pass rates vary by provider, but the hands-on portion is where most candidates struggle. Practicing the test procedure until the steps are automatic — gauge hookup, valve sequencing, differential reading — is the difference between passing and rebooking.
How Long It Lasts
Missouri backflow tester certification is valid for three years. Before it expires, you must complete an 8-hour recertification course (approximately $375 at Ranken), which includes another written and hands-on exam tested from memory.
If your credential expires, confirm the current reinstatement requirements with MDNR or your certifying provider; do not assume that the 8-hour renewal course will be sufficient.
Where the Credential Applies
Unlike plumbing trade cards, the backflow tester credential is handled under MDNR's framework rather than by local plumbing boards. That said, you still need a plumbing license from the local jurisdiction to pull permits for installing the devices — testing and installation are separate scopes.
Tested assemblies must be verified and filed with the local water authority. Each jurisdiction has its own reporting form and submission process, so confirm the paperwork requirements with the water utility before you schedule the test.
Cost Summary
| Item | Approximate Cost |
|---|---|
| Initial 40-hour course | $1,025 |
| Recertification (every 3 years) | $375 |
| Device test kits (if you own) | $300–$600 |
The investment pays back quickly — backflow testing is steady, recurring revenue that most general plumbers leave on the table.
For a complete walkthrough of backflow certification alongside Missouri's broader plumber licensing structure, see the Missouri Plumber License Guide.
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