How we verify every listing
No pay-to-play. A business is listed when a state roster shows it has certified testers and its phone or name matches an open Google profile.
The state rosters
| State | Roster | Testers listed | Who we list | Read |
|---|---|---|---|---|
| Missouri | Certified backflow prevention assembly testers (Missouri open data) (Missouri Department of Natural Resources) | 4,042 | the roster's own for-hire flag | October 6, 2026 |
| Tennessee | Active backflow testers (Tennessee Department of Environment and Conservation (Fleming Training Center)) | 4,306 | employers that are not utilities, governments, schools or plants | October 6, 2026 |
| Arkansas | Cross-connection assembly testers by county (Arkansas Department of Health) | 961 | the roster lists individuals only | October 6, 2026 |
| Oregon | Backflow assembly testers who asked to be listed (Oregon Health Authority) | 533 | an opt-in public list | October 6, 2026 |
| Utah | Certified backflow assembly testers (Utah Division of Drinking Water) | 835 | testers the state marks as commercial | October 6, 2026 |
| Indiana | Actively certified backflow device testers (Indiana Department of Environmental Management) | 2,456 | employers that are not utilities, governments, schools or plants | October 6, 2026 |
| Texas | License holders who agreed to publish their contact details (Texas Commission on Environmental Quality) | 176 | only the licensed testers who chose to publish their contact details | October 6, 2026 |
| South Carolina | Inspectors and testers of backflow prevention equipment (South Carolina Department of Environmental Services) | 357 | employers that are not utilities, governments, schools or plants | July 9, 2026 |
| Arizona | Approved Backflow Tester Company List (City of Phoenix) | 0 | companies on a water utility's approved list | August 11, 2026 |
| North Carolina | Approved Backflow Test Company List (Charlotte Water) | 0 | companies on a water utility's approved list | October 1, 2026 |
| Virginia | Backflow Prevention Assembly Service Providers (DC Water) | 0 | companies on a water utility's approved list | September 29, 2026 |
| Maryland | Backflow Prevention Assembly Service Providers (DC Water) | 0 | companies on a water utility's approved list | September 29, 2026 |
| District of Columbia | Backflow Prevention Assembly Service Providers (DC Water) | 0 | companies on a water utility's approved list | September 29, 2026 |
| California | City of San Diego approved backflow testers (City of San Diego Public Utilities Department) | 0 | companies on a water utility's approved list | September 4, 2026 |
| Ohio | City of Columbus approved backflow testers (City of Columbus) | 0 | companies on a water utility's approved list | October 1, 2026 |
| New Mexico | Albuquerque Bernalillo County Water Utility Authority certified testers and companies (Albuquerque Bernalillo County Water Utility Authority) | 0 | companies on a water utility's approved list | August 27, 2026 |
| Florida | Miami-Dade WASD certified backflow prevention assembly testers (Miami-Dade Water and Sewer Department) | 0 | companies on a water utility's approved list | June 26, 2026 |
| New Jersey | Philadelphia Water Department City-certified backflow technicians (fire sprinkler systems) (Philadelphia Water Department) | 0 | companies on a water utility's approved list | October 5, 2026 |
| Pennsylvania | Philadelphia Water Department City-certified backflow technicians (fire sprinkler systems) (Philadelphia Water Department) | 0 | companies on a water utility's approved list | October 5, 2026 |
From people to businesses
State rosters list certified people, not companies. We group testers who share an employer and phone into one business, then look the business up on Google. It is listed only when its phone matches, or its name matches in the same town, and Google shows it open. Utilities, cities, schools, unions and plants whose staff test in-house are left out. Testers listed without a company appear in tables on state and town pages, by town only.
The quality score
Every business gets a 0 to 100 score: a current certificate on the roster (30), a phone on the roster (30), a matching open Google profile (20), a website (10) and two or more certified testers (10). Below 70 it stays unpublished. Nobody can pay to change the score or the order.
Rules, utilities and prices
Every rule, utility requirement and price on this site links to the page it came from. We keep a short quote from that page and check that it is still there. Prices are shown as published, never averaged.