Best backflow preventer for sprinkler systems

As long as you have a landscape, you need to allow it to flourish – and sometimes, that is very difficult to achieve if your only moisture source is natural rainfall. An underground sprinkler system can really help, but that comes with the added consideration of installing a backflow prevention system.

It is very important to have a backflow preventer system in your home, because you want to prevent cases of contaminants in water from mixing with clean water that you normally use for drinking or cooking. These contaminants can include anything from fertilizer, bacteria, and sediments, and this means that having a backflow preventer is a requirement when installing plumbing systems in buildings.

But what exactly are these backflow prevention devices? They are actually devices that are meant to stop the unwanted reverse flows of contaminants into a fresh water system. We will look at the best four we find in the market, as well as some things to consider when getting one.

Best backflow preventers for sprinkler systems comparison table

	Maximum working water pressure	Hydrostatic test pressure	Maximum temperature of water
Zurn 1-720A Wilkins pressure vacuum breaker	150 PSI	300 PSI	110OF	Check here
Febco 765-1” BV pressure breaker	150 PSI	300 PSI	32OF to 140OF	Check here
Mueller B & K 108-904RP backflow preventer	125 PSI	200 PSI	100OF	Check here
Homewerks Worldwide VACBFPZ4B breaker	125 PSI	250 PSI	180OF	Check here

Best backflow preventers for sprinkler systems reviews

Zurn 1-720A Wilkins pressure vacuum breaker – best cost-effective choice

This backflow preventer works to prevent back siphoning, especially where there are high hazard possibilities that exist. Thanks to its compact and lightweight design, it is among the most cost-effective and low-maintenance solutions for a highly hazardous irrigation application; regardless of whether it is residential or commercial.

Specs

• Construction is entirely bonnet and bronze body, with stainless steel fasteners
• Maximum working water pressure is 150 PSI
• The hydrostatic test pressure is 300 PSI
• Maximum temperature of working water is 110^OF
• Fits in with the compliance standards of CSA, IAPMO, ASSE Lists

The entire structure is mean to withstand drops in pressure for a long time, other than preventing backflow of contaminated water. It also includes two shut-offs that are highly resilient, which allows you to construct both the air inlet valve and check valve in order to let in-line service happen periodically. The bonnet, poppet, and check assemblies are made from engineered plastic that protects the body from freeze damage.

Pros

• Promotes efficient water use and saving
• Durable and resistant to corrosion due to bronze structure
• Very high protection standards against back-siphonage
• Easy to install in any position due to the tapped ball valves
• Easy to repair when it breaks down

Cons

• Tends to break down in the winter months due to freezing

Verdict

This is a great choice, especially if you have a high-hazard back-siphonage situation in your sprinkler system and want to reduce chances of its occurrence. Just note that you need to check on it regularly due to its tendency of breaking in the winter months.

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Febco 765-1” BV pressure vacuum – best for a typical residential system, our pick

This pressure breaker is meant to give some much-needed protection against back-siphonage issues, whether the liquids are non-toxic or toxic.

Specs

• Made entirely from bronze to ensure durability
• Includes an air opening and one check valve to help in assembly
• The design helps in minimal head losses
• All parts are serviceable and easy procedures
• Its lightweight poppet seals the air opening even under minimal flow

Its structure consists of a check valve that is spring-loaded, and this will close immediately when zero flow happens or when the assembly pressure drops below 1 PSI. Moreover, it also has an air relief valve that will open when the pressure drops to 1 PSI.

Pro tip: when you are draining the system in preparation for the winter months, make sure to leave its valves 45 degrees open, or close and open them several times, in order to prevent water getting trapped between the ball and ball valve body.

Pros

• Relatively easy to install
• Does not experience cracking issues as much
• Reliable service for a long period

Cons

• Can be quite expensive, depending on where you buy them

Verdict

There are many reasons why this is our top choice for this review – but the main one is that they are the most heavy-duty option on this list. The only thing to keep in mind is following the mounting height codes, in order to keep you safe; but they will provide you with plenty of value for your money.

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Mueller B & K 108-904RP backflow preventer – best budget buy

This preventer works well in a variety of settings, including outdoor and indoor usage, and it works well for both backflow and back-siphonage prevention. Through its male hose thread outlet, you can attach it to hydrants, valves, and sill cocks.

Specs

• Comes in a 2-pack package
• Its hose threads are compliant with ANSI B1:20:7 standards and ASSE 1019
• Fits best with any ¾-inch hose thread outlet
• Stops back-siphoning

It is mainly meant to guard any of your hose connections by preventing contamination, especially in areas where temperatures do not go below freezing. Note that it has a manual drain release on its outlet side, which will allow you to drain the valve completely, although you need to operate it manually after you disconnect the hose. This will prevent accidental freezing of the valve.

Pros

• Good construction quality and provide reliable service
• Relatively affordable
• Fit well with a variety of hoses
• Easy to install

Cons

• Tend to have leaking issues, especially as you use them for a long time

Verdict

This set of backflow preventers are a good choice if you operate a shared water source and want to use some water for irrigation purposes. It is the most budget-friendly option, so you can install it if you want a system that will not break the bank.

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Homewerks Worldwide VACBFPZ4B vacuum breaker – best versatile choice

The aim of the Homewerks VACBFPZ4B preventer is to help in the transition of harmful contaminants into your irrigation water. It also prevents freezing and back siphoning.

Specs

• Compatible with plenty of standard end valves and hoses
• Operates at a maximum temperature of 82^OC/180^OF
• The maximum pressure it can handle is 125 PSI
• Resistant to corrosion, due to its brass construction
• Includes a break-off screw for permanent attachment

You can operate the preventer at a maximum temperature of 82^OC, or 180^OF, as well as a maximum operating temperature of 125 PSI. It also allows you to break off the optional screw set, thanks to the self-draining vacuum breaker.

The good news is that it is compatible with plenty of end valves and standard hoses, which include garden hoses, wall faucets, sillcocks, and hose bibs. You can also rely on it to provide quality and reliable service for a long time, thanks to the brass construction that is resistant to corrosion.

Pros

• Easy to install
• Reliable construction and great quality of service
• Provides plenty of value for your money
• Minimal issues with water spraying

Cons

• Tends to struggle with working alongside water timers

Verdict

This option will work well for you, as long as you ensure that it fits well with the model of pipes you use. However, keep in mind that a set screw is best, rather than a breakable screw, just in case the gasket is destroyed by hard water flows.

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What we do not recommend

Wilkins 34-975XL2 reduced pressure backflow preventer – has rusting issues, and long-term quality problems

This backflow pressure preventer is meant to work on portable water lines, and its assembly should help in giving protection when any potential hazards come up due to water contamination.

Thanks to its drainage hole, you can drain any remaining water in the pipe after you are done, and this will help to prevent further contamination. However, take care to avoid the backflow preventer when you are turning off the water supply, because it will spray the remaining water in the process.

Despite its good attributes though, there are some issues we have with it – especially its tendency to rust over some months of its use. It is also quite expensive, and yet the money you pay for it does not necessarily translate into high quality service and build, which is quite disappointing.

Pros

• Reliable service for some months
• Easy to install

Cons

• Since the flow faucets are steel, they have the tendency to rust over time
• Can be quite expensive

Verdict

The Wilkins 34-975XL2 preventer is easy to install and works well with a variety of piping arrangements, which makes it among the most versatile choices on this list. However, its tendency to rust over time makes it a questionable choice, especially keeping in mind how expensive it is.

View price here

What are backflow preventers, and how do they help in sprinkler systems?

Any reductions in pressure in the main water line can lead to backflow of contaminants such as manures, pesticides, fertilizers, and additional contaminants. These reach you main water supply through your irrigation pipes or sprinkler heads, or can happen through your pesticide sprayers, spray nozzles, or hose-attached sprinklers. The end result is very dire to public health, as contaminants can lead to illnesses and other issues.

When you install a proper filtration system, you can prevent back pressure backflow and/or back siphonage from occurring. There is a problem though, because not all devices can handle both backflows adequately, which is where the backflow prevention device comes in.

The types of water backflow

Backpressure

This results from imbalances in the water pressures, when the upstream pressure is lower than downstream pressure.

In the usual case in your home’s plumbing system, the water is at a higher pressure compared to the water in the municipal water system, but this is not supposed to be the case. The reason is because the higher home pipe pressure pushes the used wastewater into the municipal supply and contaminates it. Without installing a backflow prevention system, then water is at risk of contamination due to pressure differences.

Back siphonage

This is a result from a partial vacuum that is created from negative pressure. The systems that are distributing water fall behind in their pressure, resulting in a siphon-like effect where contaminated water moves to where it should not go. It can happen during emergencies that involve high water pressures, like using a fire hydrant, or a water break situation.

Varieties of backflow prevention devicesZZX

The backflow prevention device will allow the water to only flow in one direction. They come in two main types: RPs (reduced pressure principle devices), and PVB (pressure vacuum breakers). Between the two, the RPs is sturdier, so they are preferred when the backpressure situation is more dangerous.

Reduced pressure principle devices

RPs uses a series of check valves, which will work to stop water from backward flows through the water pipes. These check valves are flaps or discs that you can push open when the water is flowing in the normal direction, and allowing it to flow through. When the opposite happens and water begins to flow in the opposite direction, the check valve has a spring that closes immediately this occurs.

In terms of structure, RP is similar to double check valve assemblies. This is because of the two spring-loaded check valves in its middle section, and shut-off valves at both of its ends. Other than that, the device has a differential relief valve, which is spring-loaded and hydraulically-operating between the check valves, making the RP more suited to cross-connection control when water backflows create risks for public health.

In order to prevent backflows of water into the portable water system, the valves use a pressure differential system, which uses two pipes that lead into the relief valve. If the water pressure in both pipes is equal, the valve closes up, but differences in water pressure leads to opening of the relief valve to allow water to flow into an outflow pipe.

Vacuum breakers

These types will only help when you are solving back-siphonage issues, but they cannot save back pressure problems. They consist of an air inlet that vents out to the open air, as well as a check valve. The purpose of the check valve is to keep the air inlet closed when the condition is fine, as well as letting water flow through the pipe.

When the water pressure is less than the air pressure, the system opens the air inlet to break the suction effects of the lower water pressure, and this stops backflows from occurring. Since they work on the principle of air and water pressure differences, you will need to install them at the highest points of the system, like the highest slope in your yard or the highest sprinkler head.

What to keep in mind before installing the system

• Check your local laws and by-laws to see if you need a building permit, or any other requirements to install the system
• Before you begin digging, check if there are any underground utilities present. This should even begin before the excavation begins, and if you are unsure you should call and check.
• Watering ordinances from your local municipality
• Know if your state or municipality laws require you to have a licensed professional to install the system.
• The pipes you will need to use

Other than that, you also need to know your own specifications on:

• Water service line size
• Water pressure PSI (pressure per square inch)
• The size of the water meter you need (if you are using the municipal system), or the well pump size (if you are using a well)
• The types of backflow prevention measures that are required by the local codes
• Water flow rates in GPM (gallons per minute)

How do you determine each?

Water pressure

There are two water pressure types – static (when you shut off the water supply) and working (when you switch on the water supply). Between the two, you will need the working pressure number when looking for a backflow prevention system, which you can check by using a pressure gauge.

Size of the Water meter

If you are sorely operating on a municipal water system, then the meter should indicate the size, or you can call your water provider or utility bill if it does not. The size will usually be 1-inch, ¾-inch, or 5/8-inch. If the water comes from another source, check the pump size.

Size of the Service line

In order to do this, you get a piece of string, wrap it once around the pipe, and measure its length. PVC pipes will usually be the largest, while copper pipes are the smallest.

Flow rates

You use gallons as a standard of measurement, so calculate the time it takes to fill a gallon in seconds, and get the GPM (container size divided by time).

Final thoughts

Having a backflow prevention system in your irrigation system comes in handy, because you lessen the chances of water contamination. Hopefully, these choices will help you with the goal of getting cleaner water for use in your home and your lawn, even for the long term, with the Febco 765-1 preventer being our best choice due to its combination of durability, reliable service, and reduction of cracks.