A backflow tester is the plumbing professional who field-tests backflow prevention assemblies — the valves that stop water from flowing backward into a building's drinking supply.
The best-known credential is ASSE 5110, though many jurisdictions run their own tester certification.
This guide covers what the work involves, who hires testers, whether you need a plumbing background, what it pays, and how to qualify.
What is a backflow tester?
Backflow is water moving the wrong way through a pipe: from a property's plumbing back toward the public water main, instead of from the main into the property.
When that happens, water that isn't safe to drink can get pulled into the supply other people drink from.
Backflow prevention assemblies are the testable valves installed to stop it, and a backflow tester is the person who field-tests them.
Testing is credentialed work, not something a service tech can just pick up.
ASSE — the standards body whose backflow certification is the national reference — credentials testers under its 5110 standard, the ASSE 5110 Backflow Prevention Assembly Tester.
On a job site the same person may be called a backflow tech or a certified backflow tester; the credential behind the title is the part that matters.
The field is real and nationwide: ASSE counts more than 19,000 certified backflow professionals across the U.S. and parts of Canada, trained at more than 100 ASSE-approved schools.
ASSE's backflow series also covers the roles around the tester: 5120 Cross-Connection Control Surveyor, 5130 Backflow Prevention Assembly Repairer, 5140 Fire Sprinkler Cross-Connection Control Tester, and 5150 Backflow Prevention Program Administrator.
Testing is the assembly-level field job in that line-up, and each credential is its own — a surveyor or repairer certification is not the tester certification.
What a backflow test involves
A test is a hands-on check of one assembly.
The tester connects a dedicated test kit to the assembly and runs the field-test procedure their jurisdiction expects, confirming the valve still holds against backflow, then records the result and sends it to the program that requires the test — the local water purveyor or code authority.
The assemblies come in more than one design — the ASSE 5110 practical exam alone covers four types, abbreviated RP, DC, PVB and SVB — and the paperwork differs too.
ASSE tests to several published field-test procedures, including the USC 10th Edition, ASSE, EPA, Illinois, Missouri, one-hose and TREEO procedures, and some jurisdictions require a specific one.
What doesn't change is the point of the exercise: proving the assembly still prevents backflow.
How often each assembly gets tested is set locally.
Annual testing is a common local rule, but it isn't a federal one — our research did not confirm it from a primary source, so treat your water purveyor or local code as the authority on your schedule.
Test kits sit under local rules too: calibrating the test gauge on a set cycle is another common local requirement our research could not confirm from a primary source.
The paperwork is half the job.
A test only counts once its result reaches the program that asked for it, so testers record readings, file the pass or fail, and submit the report to the purveyor or code authority.
When an assembly fails, that finding goes in the report too — repairs are a separate discipline, with its own ASSE certification (5130).
Who hires backflow testers
The tests exist because water suppliers have to protect the public grid, and the local water purveyor — your water utility — is the authority that requires them, so utilities and their cross-connection control programs sit at the center of the field.
Plumbing contractors are the other big piece: in Louisiana, a licensed plumber adds a Water Supply Protection Specialist endorsement for the testing work, and the person doing it is the one a job ad might call a backflow plumber.
Fire-sprinkler contractors are in the field too — ASSE certifies fire-sprinkler cross-connection testers separately, as 5140.
And because assemblies are tested on a recurring local schedule, some testers build route-based businesses around the work.
If you're job-hunting rather than credentialing, start with the backflow tester jobs on HVACHires.
Do you need to be a plumber?
There is no single national answer — the credential your jurisdiction accepts decides, and the paths differ.
The national reference, ASSE 5110, is a certification rather than a licence: it requires at least five years of documented, related field experience, a 40-hour training course, a written exam, and a hands-on practical exam on the four assembly types.
That five-year rule is ASSE's, not universal — jurisdictions that run their own tester certification set their own entry rules.
Structure varies by state.
Our research found state-issued tester credentials in Texas (the TCEQ Backflow Prevention Assembly Tester licence, required for anyone who tests or repairs backflow prevention assemblies), Arkansas, Virginia, Wisconsin, Minnesota and Washington, while elsewhere testing is usually a plumber endorsement, an ASSE certificate or a water-utility rule.
Texas's BPAT licence shows how different a state path can look: it asks for a high school diploma or GED, two years of approved experience — plumbing, water-system operation, irrigation and fire-sprinkler work are among the examples — and a TCEQ-approved 40-hour course.
So: where the credential rides on the plumber licence, you do need to be — or become — a plumber first; where a standalone tester licence exists, documented experience in a related field is the gate rather than a journeyman card.
Certification rules are local — verify before you enroll
Pay and side-income potential
Backflow testers don't have their own BLS occupation.
Federal wage data lumps the pipe trades together — plumbers, pipefitters and steamfitters share SOC 47-2152 — so there is no clean national figure for testing alone.
Our salary page uses that broader occupation as the proxy and says so: the median wage for SOC 47-2152 was $63,800 a year ($30.67 an hour) in May 2025.
Treat it as the pay band of the trade testers come from, not a backflow-specific figure.
See the backflow tester salary page for the full national and state tables.
Side income is the part we won't put numbers on: per-test prices vary by market and program, and our research did not confirm typical fees, so we won't invent them.
What the structure does support is the shape of the work — assemblies are tested on a recurring local schedule, which makes testing route-shaped: a set of properties you return to.
That recurring shape is what makes testing a candidate for side income.
How to become one
Every jurisdiction sequences it slightly differently, but the ASSE path shows the shape of it — and the other routes (a state licence, a plumber endorsement, a utility program) follow the same beats: experience, course, exams, jurisdiction sign-off, renewal.
Build the field experience
ASSE 5110 eligibility starts with at least five years of documented, related field experience. Keep the records current as you work — “documented” is doing real work in that sentence.Complete a 40-hour course
The ASSE route requires a 40-hour training course, taught at ASSE-approved schools — more than 100 of them operate across the country.Pass the written and practical exams
ASSE 5110 candidates sit a written exam and a hands-on practical on the four assembly types: RP, DC, PVB and SVB.Certify the way your jurisdiction requires
ASSE is one option — many jurisdictions run their own tester certification with different entry rules. Check which credential your water purveyor or state program accepts before you enroll.Keep it current
ASSE certifications renew every three years, so plan for recertification from the start. State licences carry their own renewal cycles.
Once you're certified, the backflow tester jobs on HVACHires are where that credential goes to work.
Career information, not legal advice — certification and testing requirements are set by your local water purveyor, state program or licensing board. Confirm the current rules with the authority in your jurisdiction before you act on them.