The Difference Between Backflow Preventers and Check Valves
It's no secret that backflow is one of the most prevalent threats to the purity of our local water supply. Not only can contamination happen everywhere, but it can happen at any time if your plumbing system isn't set up to prevent it. As such, business professionals, school administrators, and homeowners are all setting out to stop this occurrence and protect the quality of their drinking water. However, this process often comes with confusion regarding what equipment they should use for the job. Two of the most commonly mentioned plumbing safety devices are backflow preventers and check valves. While these devices might seem similar at first glance, they serve distinct functions and are designed for different applications. Understanding the differences between them is crucial for maintaining the safety and reliability of your plumbing system.
What Is a Backflow Valve?
A backflow valve, also known as a backflow preventer, is a critical device in plumbing systems designed to prevent contaminated water from flowing back into the clean water supply. This is essential for maintaining the safety and purity of drinking water, irrigation systems, and other water-dependent systems. Backflow can occur due to changes in water pressure, such as when there's a break in the main water line or a sudden high demand on the system. These changes can cause water to flow in the opposite direction, potentially bringing harmful substances like chemicals, fertilizers, or sewage into the clean water supply. A backflow valve prevents this by allowing water to flow only in one direction.
Backflow Preventer Types
There are several types of backflow preventers, each suited for different applications and levels of risk. The most common types include:
- Air Gap: The simplest form of backflow prevention, an air gap is a physical separation between the water supply and any potential source of contamination. It's often used in sinks and other fixtures where the outlet is positioned above the flood level of the fixture.
- Reduced Pressure Zone (RPZ): This is one of the most reliable backflow preventers, commonly used in high-risk situations like commercial properties or industrial settings. It consists of two independent check valves with a pressure monitoring chamber between them. If either check valve fails, the pressure in the chamber will drop, allowing the device to discharge the contaminated water rather than letting it backflow into the clean water supply.
- Double Check Valve Assembly (DCVA): This device includes two check valves and is typically used in medium to low-risk situations. It's more compact than an RPZ and provides a reasonable level of protection against backflow.
- Pressure Vacuum Breaker (PVB): This type of backflow preventer is often used in irrigation systems. It includes a check valve and an air inlet valve that opens to break the vacuum if the water supply pressure drops, preventing backflow.
These backflow preventer types are all designed with one goal in mind: to protect the water supply from contamination. However, the level of protection they offer varies, and choosing the right one depends on the specific needs of your plumbing system.
What Is a Check Valve in Plumbing?
A check valve is a simpler device than a backflow preventer, designed primarily to allow water to flow in one direction and prevent it from flowing back in the opposite direction. It operates automatically, opening when the water flows forward and closing if the flow reverses. Check valves are commonly used in low-risk applications where the primary concern is preventing backflow due to gravity or minor pressure changes.
How Check Valves Work
Check valves typically use a hinged flap or a spring-loaded mechanism to control the flow of water. When water flows in the intended direction, the valve opens, allowing the water to pass through. If the flow reverses, the flap or mechanism closes, blocking the water from moving backward. This simple yet effective design makes check valves a popular choice for various plumbing applications.
Check Valve vs. Backflow Preventer: Key Differences
While both check valves and backflow preventers are designed to prevent the reverse flow of water, they do so in different ways and are suited for different applications. Here are some of the key differences between these two plumbing safety devices:
Functionality
A check valve allows water to flow in only one direction and closes if the flow reverses. It's a straightforward device that doesn't provide additional protection against backflow beyond this basic function.
A backflow preventer, on the other hand, offers more comprehensive protection. It not only prevents reverse flow but also includes mechanisms to release or divert contaminated water if the valve fails. This means that even in the event of a malfunction, the water supply remains safe.
Applications
Check valves are typically used in low-risk situations where the primary concern is preventing minor backflow. For example, they might be used in sump pump systems, where the goal is to prevent water from flowing back into the pump.
Backflow preventers are used in higher-risk situations, such as in commercial buildings, irrigation systems, or any scenario where contaminated water could pose a serious health risk. These devices are essential for maintaining the safety of drinking water and preventing cross-contamination between different water systems.
Reliability
Check valves are reliable for their intended purpose, but they can fail under certain conditions, such as if debris gets caught in the valve or if there's a sudden surge in water pressure.
Backflow preventers are generally more reliable because they are designed with multiple layers of protection. For example, an RPZ backflow preventer has two check valves and a pressure monitoring chamber, providing a fail-safe in case one component fails.
Valve to Prevent Backflow: Choosing the Right Device
-
Double Check Valve Backflow PreventerMSRP: $2,599.00 MSRP: $2,599.00 Pro Price: $1,109.00 Pro Price: $1,109.00 Special Price $0.00 -
Double Check Valve Backflow Preventer (Grooved)MSRP: $2,729.00 MSRP: $2,729.00 Pro Price: $1,459.00 Pro Price: $1,459.00 Special Price $0.00
-
Lead Free Double Check Backflow PreventerMSRP: $3,229.00 MSRP: $3,229.00 Pro Price: $1,369.00 Pro Price: $1,369.00 Special Price $0.00 -
Lead Free Double Check Backflow Preventer (Grooved)MSRP: $3,429.00 MSRP: $3,429.00 Pro Price: $1,519.00 Pro Price: $1,519.00 Special Price $0.00 -
Reduced Pressure Zone Backflow PreventerMSRP: $3,089.00 MSRP: $3,089.00 Pro Price: $1,299.00 Pro Price: $1,299.00 Special Price $0.00 -
Reduced Pressure Zone Backflow Preventer (Grooved)MSRP: $3,259.00 MSRP: $3,259.00 Pro Price: $2,059.00 Pro Price: $2,059.00 Special Price $0.00
-
Reduced Pressure Zone AssemblyMSRP: $4,209.00 MSRP: $4,209.00 Pro Price: $1,759.00 Pro Price: $1,759.00 Special Price $0.00 -
Lead Free Reduced Pressure Zone Assembly (Grooved)MSRP: $4,589.00 MSRP: $4,589.00 Pro Price: $1,929.00 Pro Price: $1,929.00 Special Price $0.00
When it comes to choosing a valve to prevent backflow, it's essential to consider the specific needs of your plumbing system. If you're dealing with a low-risk situation, such as preventing water from flowing back into a sump pump, a check valve may be sufficient. However, if you're concerned about protecting your drinking water supply or preventing cross-contamination in an irrigation system, a backflow preventer is the better choice.
Plumbing Safety Devices: Protecting Water Quality
Both check valves and backflow preventers play critical roles as plumbing safety devices. They are designed to protect water quality by preventing the reverse flow of contaminated water into clean water supplies. However, the level of protection they offer differs, and it's crucial to choose the right device for your specific application.
Water Contamination Prevention: A Shared Goal
At the end of the day, both check valves and backflow preventers serve the same overarching purpose: water contamination prevention. By controlling the direction of water flow and blocking contaminated water from re-entering the clean water supply, these devices are essential components of any plumbing system.
Conclusion
In the ongoing battle to protect our water supply from contamination, understanding the differences between check valves and backflow preventers is crucial. While both devices are designed to prevent backflow, they do so in different ways and are suited for different applications. Check valves are ideal for low-risk situations, where the primary concern is preventing water from flowing back into the wrong part of the system. Backflow preventers, on the other hand, are necessary for high-risk applications, where the potential for contamination is significant. By choosing the right valve to prevent backflow and maintaining it properly, you can help protect your water supply from contamination and preserve its purity for years to come.
