The rules
| Question | Medford Water's answer |
|---|---|
| Who needs one | In-ground irrigation; also pool, solar, fire sprinkler and well systems |
| Device types | Atmospheric vacuum breaker (AVB), pressure vacuum breaker (PVB), double check valve assembly (DCVA), reduced pressure backflow assembly (RPBA) |
| Which for plain irrigation | A double check for "irrigation systems without chemical injection"; PVB or AVB only where there is no possibility of backpressure; irrigation with chemical injection needs an RP or air gap |
| Permit | "Plumbing permits are required by the City of Medford or Jackson County when installing backflow prevention assemblies" |
| Testing | At installation and at least once a year, by a State of Oregon certified tester (AVBs excepted) |
| Who pays for what, single-family | Owner pays installation and the first test; the residential program covers annual testing and maintenance, not major repairs or replacement |
| New services | Locked off until backflow compliance and the initial test are verified |
Program and device facts are from the backflow page (modified 25 July 2025); installation rules are from Medford Water's standards for backflow prevention assemblies, approved October 2012.
Installation details that change the quote
- Location. Downstream of the meter, at or near the property line, readily accessible for testing.
- Height. Some devices must sit 6 inches to a foot above the highest sprinkler, which Medford Water warns is hard on sloped lots. A double check can go below grade in a drained vault with plugged test cocks; a sump pump is required where groundwater is possible.
- Clearance. Assemblies 2 inches and smaller need 12 inches below and 3 inches each side; maximum installed height 5 feet.
- Freeze protection. "The assembly must be protected from freezing," so budget for an insulated cover.
- Thermal expansion is the installer's job to plan for.
What it means when you hire
In our data the busiest Medford backflow installers are landscape firms, not plumbers. Medford Water tells homeowners to check the Landscape Contractors Board records for Jackson County to see whether a contractor is licensed to install backflow assemblies. Ask the installer who pulls the plumbing permit and who does the first test, and get the test report: Medford Water needs it before it takes the device into its residential program.
What 449 Medford backflow permits show
| Measure | Medford irrigation backflow |
|---|---|
| Permits, October 2023 to September 2026 | 449 |
| Firms / active in the last 12 months | 62 / 24 |
| Usual filed value | $750 |
| Middle half of installers' usual job (24 firms with 3+ permits) | $600 to $1,000 |
| Busiest firm / its share of permits | New View Landscape & Ground Maintenance / 29.8% |
| Finished (permits a year or more old) | 44.4% |
| Busiest / quietest month | March (216) / December (59) |
This is the most seasonal trade in our Medford data: filings in March run at 216 against an average month of 100, as sprinkler systems are started for the season, and fall to 59 in December. Book a new install in winter if you can. Only 44.4% of older backflow permits show as finished in the City's file, low next to Medford's other trades, so ask your installer to confirm the inspection and test were recorded. In our file 37.1% of these firms matched an Active CCB license under the name on the permit; landscape contractors are licensed by a separate board, which we do not match, so check that board too.
Compare Medford backflow installers by permit record →
Related
Filed values in detail: Medford backflow cost. Licenses in Medford: Medford contractor license lookup and checking an Oregon contractor. Looking up a permit: Medford building permit search. Permit counts by year: Medford permit statistics.
What this does not tell you
Our records are City of Medford permits; they do not include annual test results, which go to Medford Water, or installs under Jackson County permits outside the city. Medford Water's pages do not give the monthly program charge, so ask the utility.
How we know this
Rules are from Medford Water's backflow prevention page (modified 25 July 2025) and its standards for backflow prevention assemblies (Resolution 1501, October 2012), read 23 October 2026. Permit counts and filed values are City of Medford permits on homes classified as irrigation backflow, October 2023 to September 2026; the finished share uses permits a year or more old.
Numbers come from City of Medford building, electrical, mechanical and plumbing permits on single-family, duplex and cottage homes (the city's TRAKiT permit exports), data through October 16, 2026. Nobody paid to be on this page and nobody can.
Questions
- Do I need a backflow preventer for my sprinklers in Medford?
Yes. Medford Water says in-ground irrigation systems must have backflow protection under state health codes, as must pool, solar, fire sprinkler and well systems (Medford Water, page modified 25 July 2025, read 23 October 2026).
- How often does a backflow device have to be tested in Medford?
At installation and every 12 months after, except atmospheric vacuum breakers. Medford Water says it does not always send reminders.
- Who tests backflow devices in Medford?
A tester certified by the State of Oregon; Medford Water links the state's certified tester list. For single-family homes, Medford Water runs a residential program, paid by a small monthly charge on the water bill, that covers annual testing and maintenance but not major repairs or replacement. Call 541-774-2430 to enroll a device.
- Do I need a permit to install a backflow device in Medford?
Yes. Medford Water's standards say plumbing permits are required by the City of Medford or Jackson County when installing backflow prevention assemblies, and the installation must be inspected and tested.
- How much does backflow installation cost in Medford?
The usual filed value on a Medford irrigation backflow permit was $750, and the middle half of installers' usual jobs ran $600 to $1,000 in our data.
Build your own list
Every firm with that kind of permit on record. Pick what you value. The list moves.
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For one city
- Backflow Prevention — Medford Water (accessed 2026-10-23)
- Standards for Backflow Prevention Assemblies — Medford Water (Resolution 1501, October 2012) (accessed 2026-10-23)