Your water utility and local plumbing code decide which device your sprinkler needs. In short: a PVB is the cheap, common choice when it can sit above every sprinkler head; a double check is only meant for low (non-health) hazards; and an RPZ is the high-hazard device that many places demand when the irrigation water could carry fertilizer or chemicals. Before you buy or replace anything, ask your utility which type it accepts, in writing.
Key takeaways
- A plain check valve or "anti-siphon" sprinkler valves are not a substitute for a testable backflow preventer.
- A PVB has to be mounted about 12 inches above the highest sprinkler head, which rules it out on some sloped yards.
- Austin Water says double checks "should be used to isolate only non-health hazards." That's the main reason some utilities reject them on irrigation.
- Rules differ: Naperville, IL requires an RPZ on lawn sprinklers, Fort Worth's irrigation rules describe a double check, and Dallas doesn't require yearly tests on lawn sprinklers.
- If a tester says your in-ground double check is an "automatic fail," ask which rule says so before paying for a replacement.
What's the difference between an RPZ, a double check and a PVB?
All three are testable assemblies: they have small ports called test cocks where a certified tester connects a gauge. That's what separates them from a simple check valve. As one forum member put it, "a check valve can't be tested and a backflow prevention valve can" (TractorByNet).
- PVB (pressure vacuum breaker): one spring-loaded check valve plus an air inlet that opens when supply pressure drops, so water can't be sucked back (back-siphonage). Above ground, higher than the sprinklers.
- Double check (DCVA, "dbl-check"): two check valves in a row, no air inlet or relief valve, so it can sit in a valve box below ground.
- RPZ (reduced pressure zone assembly): two check valves with a relief valve between them that dumps water if either check leaks. Above ground so it can drain.
| PVB | Double check (DCVA) | RPZ | |
|---|---|---|---|
| Protects against | Back-siphonage only | Back-siphonage and back-pressure | Back-siphonage and back-pressure |
| Hazard level | Common on lawn irrigation (most Minnesota lawn systems, per the Star Tribune) | Non-health (low) hazard only, per Austin Water | High (health) hazard |
| Where it can go | Above ground, about 12" above the highest head | Above or below ground (below-grade allowed in some cities with conditions) | Above ground, with room to drain |
| Discharges water? | Can spit from the air inlet | No | Yes, from the relief valve when it trips |
| Typical cost | Lowest | Middle | Highest (an RPZ was about $250 in Chicago in 2020 and about $800 from a supplier) |
Prices reported 2020-2025 (indicative): about $125 for a 1-inch residential preventer at a big-box store; RPZs from about $250 to $800 for the part; installed replacement quotes of $590 (Jacksonville) and $1,100 for a below-ground irrigation backflow (Chattanooga) (TractorByNet, WTTW, r/jacksonville, r/Chattanooga). Pipe size, permit, labor and digging out the old device drive the total. Ask for a written, itemized quote.
Do anti-siphon sprinkler valves or a check valve count as a backflow preventer?
Usually not. A homeowner on the Rachio forum was told by store staff that "there is no need for it if the sprinkler valves have anti-siphon" (Rachio Community). Utilities generally want one testable assembly they can track, and the TractorByNet thread is blunt: "Check valves are not approved."
Why do in-ground double checks fail (or get rejected) in some cities?
There are three separate reasons, and it helps to know which one you're being told.
- Hazard classification. Lawn irrigation can hold fertilizer, herbicide and stagnant water. If your utility classes that as a health hazard, a double check isn't enough, since Austin Water says double checks are for "non-health hazards" only (Austin Water). That points you to a PVB or an RPZ.
- Below-ground test cocks. A double check buried in a valve box can sit in muddy water. Utilities that still allow it set conditions. Fort Worth, for example, requires "at least six inches of gravel under the assembly," says it "must not be covered by sod, dirt, or construction debris," and requires threaded plugs in the test ports of below-grade assemblies (City of Fort Worth).
- A new local rule. In Chattanooga, posters described Tennessee American Water tightening rules ahead of January 1, 2027. A certified tester in that thread called an in-ground double check "an automatic fail, and must be replaced," and a homeowner reported a $1,100 replacement quote (r/Chattanooga).
Layout matters too. On Long Island, installers noted that "a double check might not be allowed" depending on the site, and that some Nassau County authorities accept a PVB, which is "much cheaper" (HeatingHelp). If no PVB can be mounted above your heads, you're choosing between a double check (if allowed) and an RPZ. Already failed? Read My backflow failed the test: repair or replace? before approving a quote.
What do NYC, Chicago, Dallas, Fort Worth and Austin require?
Here's what we could confirm from official pages and press coverage as of October 2026. Where a source is silent on residential sprinklers, we say so.
| City | What the source says about device type | Testing | Who tests / how reports are filed |
|---|---|---|---|
| New York City (DEP) | The DEP program targets buildings with hazardous uses (medical offices, laundromats, car washes, funeral homes). RPZs are preferred; a double check can be acceptable on the main line if internal hazards have their own RPZs. Plans are filed by a registered architect or professional engineer. Residential lawn irrigation is not addressed in the sources we found (NYREJ, 2009) | Every year | Tester certified by the NYS Department of Health (NYS DOH) |
| Chicago | The Department of Water Management requires an RPZ for hydrant connections, tested by a certified Cross-Connection Control Device Inspector (CCCDI) (WTTW, 2020). In the suburbs, Naperville says "State of Illinois law" requires that "all sprinkler systems include an RPZ" (Naperville). Chicago's own rule for private sprinklers: confirm with the city | Naperville: at installation, then annually | CCCDI; suburban reports via BSI Online (Naperville) |
| Dallas | No irrigation device type listed on the test-report page | "For irrigation systems like lawn sprinklers, annual inspections are not mandatory." Test when newly installed, repaired or replaced. High-hazard assemblies are tested yearly | Tester registered with Dallas Building Inspection; reports via SwiftComply, $10 per passed test (City of Dallas) |
| Fort Worth | Irrigation needs "an appropriate backflow assembly"; the irrigation rules describe a DCVA that must be "readily accessible." Below-grade installs allowed with conditions. Homes with wells, rainwater harvesting or lake pumps need an above-ground RPZ at the meter | At installation, repair or relocation, "and annually thereafter"; "Commercial class irrigation backflows are tested annually." The page doesn't say explicitly whether residential irrigation is yearly | TCEQ-licensed tester registered with the city; reports via Vepo/Envirotrax (City of Fort Worth) |
| Austin | Assemblies are typically required for "irrigation systems, fertilizers, or auxiliary water sources," must match the hazard, and must be on the USC Foundation's approved list. Double checks for "non-health hazards" only | Subject to "annual inspection, maintenance, testing and reporting requirements" | State-licensed BPAT registered with Austin Water (Austin Water) |
The three Texas cities share one state licensing system but run different programs, and an Illinois suburb's RPZ rule doesn't settle what Chicago proper requires. Check your New York City, Chicago, Dallas, Fort Worth or Austin page, then confirm with the utility.
How do I choose the right backflow preventer for my sprinkler system?
Use this decision path, then get the answer confirmed by the utility or a licensed plumber:
- Ask the utility what it accepts for residential irrigation, and whether that changes if you inject fertilizer or use a well, rainwater or pond water. (In Fort Worth, an auxiliary source means an RPZ at the meter.)
- Can the device sit above the highest sprinkler head? If yes and the utility allows it, a PVB is usually the cheapest option.
- Heads above the supply, or no room for a PVB? Ask whether a double check is allowed and under what installation conditions (above or below ground).
- High hazard, chemical injection, or the utility simply requires it? Plan for an RPZ, installed above ground where the relief valve can drain, and think about freeze protection.
- Pull a permit if one is needed, and book the installation test by a certified, registered tester. Dallas and Fort Worth both require a test on a new or replaced assembly. Budget the test too: see our backflow test cost guide.
FAQ
Is an RPZ better than a double check? It covers higher hazards, but costs more, must be above ground and can discharge water. "Better" means whatever your utility requires for your hazard level.
Can I replace my double check with a PVB? Often, if your utility accepts a PVB for irrigation and you can mount it about 12 inches above the highest sprinkler head. A permit and an installation test are usually needed. Confirm first.
My tester says my in-ground double check is an automatic fail. Is that true? It may be under a new local rule, or because the installation doesn't meet below-grade conditions. Ask the tester which rule applies, then confirm it with the utility before you agree to a replacement.
Does Dallas require yearly backflow testing on lawn sprinklers? According to Dallas Water Utilities, annual inspections are not mandatory for irrigation systems like lawn sprinklers. Testing is required when a device is newly installed, repaired or replaced. High-hazard assemblies are tested every year.
Do I need an RPZ on my sprinkler in Illinois? Naperville says State of Illinois law requires an RPZ on all sprinkler systems, tested at installation and yearly. In Chicago, confirm with the city.
Compare providers for your device type
Compare providers on Backflow Compass and include the device type, size and location (above or below ground) in your quote request so testers can price it accurately. Backflow Compass is an independent directory, not an installer or testing company.
Disclaimer: This article is general information, not plumbing, legal or compliance advice. Device requirements are set by your water utility and local plumbing code, and they change. Confirm the accepted device type with your utility or a licensed plumber before buying or replacing anything.
Sources
- TractorByNet: check valve vs backflow preventer
- Austin Water: Backflow prevention overview
- City of Fort Worth: Backflow and Cross Connection Control
- City of Dallas: Backflow Test Reports
- City of Naperville: Lawn Sprinklers/RPZ Backflow Preventer Permit
- City of Naperville: Cross Connection Control Program
- WTTW: How a piece of plumbing hardware threw a wrench into Chicago's urban ag movement (2020)
- NYREJ: A look at New York City DEP's back-flow device program (2009)
- NYS Department of Health: Backflow Tester Certification Instructions and Procedures
- Change in backflow devices (r/Chattanooga)
- HeatingHelp: Is a double check required on residential irrigation (Kings Park, Long Island)?
- Rachio Community: What backflow would you recommend?
- Is everyone getting their sprinkler backflow assemblies inspected yearly? (r/FortCollins)
- JEA backflow inspections (r/jacksonville)
- Star Tribune: New backflow preventer testing requirements (2016)
Independent general information. Requirements and prices depend on scope, locality, technical standards and current regulations. Verify critical details with qualified professionals and relevant authorities.