Best Backflow Preventers (2026): PVB vs RPZ vs Double Check

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Quick answer from a licensed plumber: For a typical lawn sprinkler system, a pressure vacuum breaker like the Zurn Wilkins 720A, mounted at least 12 inches above the highest downstream piping or sprinkler head. Where backpressure is possible or a PVB will not fit the height rule, a reduced pressure zone assembly like the Febco 825Y. A double check, like the lead-free Febco LF850 (named here, not linked), is only for connections your authority rates a non-health hazard. Your water authority decides which type you need and how often it must be tested.

Our pick for most sprinkler systems: the Zurn Wilkins 720A pressure vacuum breaker. Check the 1 in. Zurn Wilkins 720A on Amazon

A backflow preventer for a sprinkler system or a water service is a testable assembly: check valves, test cocks and a shutoff valve at each end. This page compares the three common types, pressure vacuum breakers (PVB), reduced pressure zone assemblies (RPZ) and double checks, and looks at four assemblies. It links the three that Amazon.com sold when we checked; the Febco LF850 is named but not linked. The type definitions come from the USC Foundation for Cross-Connection Control and Hydraulic Research, and every spec comes from the maker’s spec sheet.

If you are protecting a hose bibb rather than a sprinkler line or service, you need a different, smaller device; our guide to vacuum breakers and anti-siphon valves covers those.

Backflow Preventers Compared

Assembly	Type	Protects against (USC / EPA / maker)	Hazard (USC)	Max pressure / temp (maker)	Drinking water?
Zurn Wilkins 720A	PVB	Backsiphonage only	Health or non-health	150 psi / 110°F	No (non-potable only)
Febco 825Y	RPZ	Backpressure and backsiphonage	Health or non-health	175 psi / 140°F	No, per Febco
Zurn Wilkins 975XL	RPZ	Backpressure and backsiphonage	Health or non-health	175 psi / 180°F	No (non-potable only)
Febco LF850 (not linked)	Double check	Backpressure and backsiphonage	Non-health only	175 psi / 140°F	Lead free

Type and hazard columns from the USC Foundation’s definitions, backpressure from the EPA manual and the makers; ratings from the Zurn and Febco spec sheets. Each linked assembly was sold by Amazon.com and in stock on October 6, 2026. The Febco LF850 is not linked: when we checked on October 6, 2026, its Amazon listings were sold by a third-party seller.

PVB vs RPZ vs Double Check: What Each One Does

Two words first. The USC Foundation defines backsiphonage as backflow caused by a drop in supply pressure that pulls a vacuum in the system, and backpressure as pressure downstream, from a pump, elevation or air pressure, that rises above supply pressure and pushes water backward. It also sorts hazards into pollutants (non-health hazard: color or odor) and contaminants (health hazard: illness or death if swallowed).

Pressure vacuum breaker (PVB). One loaded check valve plus a loaded air inlet valve on its outlet side, with test cocks and shutoffs. USC: protects against health or non-health hazards, backsiphonage only. The standard Zurn and Febco cite for it is ASSE 1020.
Double check valve assembly (DCVA). Two independent check valves with test cocks and shutoffs. USC: non-health hazards only. Watts cites ASSE 1015 for its LF007.
Reduced pressure principle assembly (RP or RPZ). Two independent check valves with a pressure differential relief valve between them. USC: health or non-health hazards. Zurn and Febco cite ASSE 1013.

The USC Foundation also defines a spill-resistant vacuum breaker (SVB), which works like a PVB but adds a bleed/vent port. We did not find an SVB sold by Amazon.com with maker documents, so none is linked here.

Which One Your Water Authority Will Accept

You do not choose the type on your own. Watts’ spec sheet says only cross-connections that local inspection authorities identify as non-health hazard may use a double check, and tells you to check with the local authority about orientation and testing frequency. Zurn says local codes govern installation. The EPA’s Cross-Connection Control Manual describes water systems that keep a list of every testable device and make sure each one is tested by certified test personnel on the schedule in the local ordinance.

Plumber’s note: call the water utility or the building department before you buy. Ask which type they require for your connection, whether a permit is needed, and who may install and test it. A sprinkler line with a fertilizer or chemical injector is a different connection from a plain lawn line, and the authority may require a different assembly.

Install Rules the Makers Print

PVB height: Zurn and Febco both say at least 12 inches above the highest downstream piping and outlet. Zurn adds that a PVB cannot go where backpressure could occur or where spillage from its vent could cause damage.
RPZ drain: Zurn says to mount the 975XL 12 to 30 inches above an adequate drain, with an air gap adapter if it is indoors. Febco says its flood sensor does not replace proper drainage for a discharge.
Access for testing: Febco’s 765 sheet says assemblies must be easy to reach for maintenance and periodic testing. Zurn calls for side clearance for testing.
Pressure behind the assembly: Febco warns that thermal expansion or water hammer downstream can raise pressure, and that excess pressure should be eliminated to avoid damage. On a house service, see why pressure climbs behind a check or backflow device.
Freezing: Febco says its 765 needs freeze protection and points to its own freeze-protection service instruction. The freeze sensors on the Febco and Watts assemblies only send alerts, and both makers say user action is still required.

Best Pressure Vacuum Breaker for Sprinklers

Zurn Wilkins 720A Pressure Vacuum Breaker

Type: PVB, ASSE 1020 listed · backsiphonage only · 150 psi max · 110°F max · bronze body · two test cocks and two full port shutoff valves · non-potable use only · linked in 3/4 in. (34-720A) and 1 in. (1-720A)

Zurn designs the 720A pressure vacuum breaker for irrigation lines, to protect the drinking water supply against backsiphonage where a health hazard exists. Zurn lists an approved check valve, a vacuum relief, two test cocks on the center line of the valve, and a full port shutoff valve at each end. Zurn lists it as ASSE 1020, UPC listed, CSA certified and approved by the USC Foundation, and the USC list carries the 720A in both sizes we link.

The install rules are what matter. Zurn says to mount it at least 12 inches above the highest piping or outlet downstream, and that a pressure vacuum breaker cannot go where backpressure could occur or where water spilling from its vent could cause damage. Zurn rates it to 150 psi and a maximum water temperature of 110°F, and its page says the bronze build gives protection against the elements and light freezes. That is not a winter rating: Zurn’s typical-installation drawing for cold climates that require winterization shows inlet and outlet drain valves.

ASSE 1020 listed and on the USC approved list in 3/4 and 1 in.
Test cocks on the valve center line
Bronze body and bonnet, per Zurn
Full port shutoff valves included

Backsiphonage only: no backpressure service
Must sit 12 in. above the highest downstream piping or outlet
For non-potable use only, per Zurn
Vents water, so it cannot go where spillage does damage

Verdict: The pick for a typical lawn sprinkler system where the local authority accepts a PVB.

Check the 3/4 in. Zurn Wilkins 720A on Amazon

Check the 1 in. Zurn Wilkins 720A on Amazon

Best Reduced Pressure Zone (RPZ) Assembly

Febco 825Y Reduced Pressure Zone Assembly

Type: RPZ, ASSE 1013 · backpressure and backsiphonage · 175 psi max · 32 to 140°F · bronze body · two Y-pattern check valves plus a relief valve · flood sensor on the relief valve (alerts need an add-on connection kit) · linked in 1 in.

When backpressure is possible, or when the sprinkler line sits where a PVB cannot meet its height rule, the reduced pressure zone assembly is the step up. The EPA’s Cross-Connection Control Manual says pressure vacuum breakers do not protect against backpressure, and describes RPZs protecting against backpressure as well as backsiphonage on high hazard installations. Febco’s 825Y has two independent, spring-loaded check valves and a differential relief valve between them. Febco says the assembly holds the zone between the checks at least 5 psi below inlet pressure, and if that difference drops to 2 psi, the relief valve opens and dumps water to keep it. Febco lists irrigation systems among its uses and says it meets ASSE 1013, AWWA C511 and CSA B64.4, with USC Foundation approval. The USC list carries the 825Y in the 3/4 and 1 inch sizes.

Two things to plan for. First, an RPZ discharges water by design, so it needs drainage; Febco’s flood sensor can send an alert when the relief valve dumps, but only with an add-on connection kit, and Febco says the sensor does not replace proper drainage. Second, Febco’s spec sheet says it is illegal to use the standard 825Y in any system that provides water for drinking or dishwashing in the United States. Use this one on irrigation.

We link the 1-inch 825Y. Not linked: when we checked on October 6, 2026, the Amazon listing for the 3/4 in. 825Y was sold by a third-party seller.

Protects against backpressure and backsiphonage
ASSE 1013, AWWA C511 and CSA B64.4, per Febco
All internal parts serviceable in line, per Febco
Flood sensor ready for relief valve alerts

Not for drinking water service, per Febco’s spec sheet
Relief valve discharges water: plan the drain
Flood alerts need an add-on connection kit
Linked only in 1 in.

Verdict: The pick for an irrigation line that needs RPZ protection.

Check the 1 in. Febco 825Y on Amazon

RPZ Rated for Hotter Water

Zurn Wilkins 975XL Reduced Pressure Principle Assembly

Type: RPZ, ASSE 1013 listed · backpressure and backsiphonage · 175 psi max · 180°F max · bronze body and covers · full port ball valves · mount 12 to 30 in. above a drain · non-potable use only · linked in 1 in. (1-975XL)

The 975XL is Zurn’s reduced pressure principle assembly. Zurn designs it to protect against both backsiphonage and backpressure where a health hazard exists, and lists it as ASSE 1013, cUPC listed, CSA B64.4 certified, AWWA C511 compliant and approved by the USC Foundation. The USC list carries the 975XL in the 1-inch size we link. Zurn rates it to 175 psi and 180°F, a higher temperature than the Febco 825Y’s 140°F.

Zurn is specific about the install: mount it at least 12 inches and no more than 30 inches above an adequate drain, with room at the sides for testing and maintenance, so no part of it can be submerged. If it goes indoors, Zurn says to fit an air gap adapter. Like the Febco, Zurn marks it for non-potable applications only. Zurn says the first and second checks can be serviced without removing the relief valve or the whole assembly from the line.

Rated to 180°F, per Zurn
ASSE 1013 listed and on the USC approved list in 1 in.
Checks serviceable without pulling the relief valve
Clear mounting height range: 12 to 30 in. above a drain

For non-potable use only, per Zurn
Needs an air gap adapter indoors
Linked only in 1 in.
Discharges water like any RPZ

Verdict: A strong RPZ for irrigation and other non-potable lines, with clear install limits from Zurn.

Check the Zurn Wilkins 975XL on Amazon

Best Double Check for Low-Hazard Lines

Febco LF850 Double Check Valve Assembly

Type: double check (DCVA) · backpressure and backsiphonage · non-health hazard only · 175 psi max · 32 to 140°F · lead free cast copper silicon alloy · about 1 psi drop across each check at no flow · freeze sensor (alerts need a kit) · not linked

A double check valve assembly is two independent check valves with test cocks and a shutoff at each end. The USC Foundation says it may only protect against a non-health hazard, a pollutant that affects color or odor but does not make people sick. Febco designs the LF850 for that service and says it protects against backsiphonage and backpressure. It is lead free: Febco says the wetted surface contains less than 0.25 percent lead by weight.

Febco’s spec sheet lists a pressure drop of about 1 psi across each check valve at no flow, a 175 psi rating and a 32 to 140°F range. Its approvals block shows the ASSE 1015 and CSA B64.5 marks, AWWA C510 conformance and USC Foundation approval. The USC list carries the LF850 in the 3/4 and 1 inch sizes. Febco’s typical installation drawing shows 12 inches of clearance to a fixed structure. It carries a freeze sensor that only sends alerts with a kit sold separately, and Febco says the sensor cannot prevent a freeze. One thing to raise with your authority: both Amazon listings we checked include that freeze sensor, and the approvals block on Febco’s sheet marks option FZ, the freeze sensor, as not listed, while the same sheet says the sensor does not alter the assembly’s functions or certifications.

Not linked: when we checked on October 6, 2026, the Amazon listings for the 3/4 in. and 1 in. LF850 were sold by a third-party seller.

Lead free wetted surfaces, per Febco
Protects against backpressure as well as backsiphonage
About 1 psi drop per check, per Febco
LF850 is on the USC approved list in 3/4 and 1 in.

Non-health hazard only, per the USC Foundation
Freeze alerts need a kit sold separately
Febco’s sheet marks the freeze sensor option (FZ) as not listed

Verdict: The pick where your water authority has rated the connection a non-health hazard and accepts a double check.

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What About the Febco 765?

Febco also makes the 765 pressure vacuum breaker. Febco rates it to 150 psi and 32 to 140°F and gives it a plastic bonnet meant to protect the valve body from freeze damage. Its Amazon listing switched between Amazon.com and a third-party seller across our checks, so we do not link it. Like the 825Y, Febco’s spec sheet says the standard 765 is not for drinking water systems.

What About the Watts LF007?

Watts makes the LF007, a lead-free double check valve assembly. Watts lists it to ASSE 1015, AWWA C510, IAPMO PS31 and CSA B64.5, rates it to 175 psi and 33 to 180°F, and says in its manual that a licensed contractor must install it under local codes. The 3/4-inch Amazon listing moved from Amazon.com to a third-party seller between our checks, so we do not link it.

Testing: What to Expect

Every assembly on this page has test cocks for a reason. Watts says its double check must be tested at least once a year under local codes and again after any maintenance. The USC Foundation trains testers on four assembly types: PVB, SVB, double check and RPZ. ASSE International certifies backflow assembly testers under its 5110 program; its requirements include five years of related field experience, a 40-hour course and a practical exam on ASSE 1013, 1015, 1020 and 1056 assemblies, and the certification runs for three years.

Your local authority decides who may test your assembly. Testers read the test cocks with a differential pressure gauge; our backflow test kit guide compares the kits.

Before You Buy

Ask the authority first. It decides which type your connection needs.
Check the USC list. The USC Foundation’s list of approved assemblies names the type, maker, model, size and orientation; it says using shutoff valves other than those listed voids its approval.
Match potable or non-potable. The standard Febco 825Y and 765 and the Zurn 720A and 975XL are not for drinking water, per their makers.
Plan the height and the drain. A PVB has a 12-inch rule; an RPZ needs somewhere for its discharge to go.
Plan for the test. Watts says at least once a year for its double check; your local code sets the schedule.

FAQ

What is the difference between a PVB, an RPZ and a double check?

A PVB has one loaded check valve and an air inlet, and the USC Foundation says it protects against backsiphonage only. A double check has two check valves and may only protect against a non-health hazard. An RPZ adds a relief valve between two checks and protects against health and non-health hazards. The RPZ and double check also handle backpressure.

What backflow preventer do I need for a lawn sprinkler system?

Your water authority or plumbing inspector decides. Zurn designs its 720A pressure vacuum breaker for irrigation lines and says it must sit at least 12 inches above the highest downstream piping or outlet. Febco lists its 825Y RPZ for irrigation systems too, and the EPA manual says an RPZ also handles backpressure, which a PVB does not.

How often does a backflow preventer have to be tested?

As often as your local code says. Watts says its double check must be tested periodically in compliance with local codes, but at least once a year, and again after any maintenance. The EPA Cross-Connection Control Manual says testable devices should be tested by certified test personnel at the intervals set in the local ordinance.

Can I use these on my drinking water line?

Only the lead-free ones. Febco says its standard 825Y must not be used where water is for drinking or dishwashing, and Zurn marks the 720A and 975XL for non-potable use only. The Febco LF850 is lead free, per Febco, but it is a double check, which the USC Foundation limits to non-health hazards. For a health hazard on a drinking water line, ask your authority which lead-free assembly it requires; none of the PVBs or RPZs linked here qualify.

Why does my RPZ dump water?

That is the relief valve doing its job. Febco says its 825Y relief valve opens and discharges when the pressure difference between the supply and the zone between the checks drops to 2 psi, under no flow or reversed flow. Plumber’s note: a relief valve that keeps dumping needs a tester or plumber to find out why.

Why Trust Plumbing Picks

Plumbing Picks is written by a licensed Georgia journeyman plumber. Every spec here comes from the maker spec sheets and the USC Foundation, EPA and ASSE documents linked below, or from the Amazon listings we link; nothing comes from hands-on testing. On October 6, 2026, every linked listing was in stock and sold by Amazon.com. If you buy through a link we may earn a commission at no extra cost to you. Nobody pays to be included here. More on who writes this and how we pick.

Sources

Bottom Line

Ask your water authority which type it requires, then buy that type from its approved list. For a plain lawn sprinkler line where the authority accepts a pressure vacuum breaker, the Zurn Wilkins 720A. Where backpressure is possible on an irrigation line, an RPZ like the Febco 825Y or Zurn Wilkins 975XL; neither is for drinking water service, per Febco and Zurn. For a low-hazard line, a lead-free double check like the Febco LF850. Mount it where it can be tested, give an RPZ a drain, and plan on testing it on your local schedule.