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Blogs from March, 2024

Backflow Prevention: A Complete Guide to Safe Water

Backflow prevention for residence

Backflow prevention for residence

What is a backflow preventer?

A backflow preventer is a one-way valve. When backflows are sensing a backflow condition, when they are working correctly, they will introduce air into the system to break the vacuum The backflow preventers that are currently being required in Central Florida are: RPA (Reduced Pressure Assembly), and a PVB (Pressure Vacuum Breaker). A backflow preventer is a device used to protect potable water supplies from contamination or pollution due to backflow. Backflow occurs when water flows in the opposite direction to its intended direction, potentially allowing contaminants to enter the clean water supply. This can happen due to changes in pressure within the water system, such as during a water main break, or when there's a cross-connection between the potable water supply and a source of contamination, such as a chemical line or irrigation system.

Backflow preventers are installed in the plumbing systems either within 18" of the water meter or at the point of connection from your potable water and irrigation system. These devices are essential for maintaining the safety and quality of drinking water in residential, commercial, and industrial settings. They are required by building codes, water purveyors and regulations to be installed in certain plumbing systems to protect public health and safety.

Types of backflows currently required in Central Florida: 


 A reduced pressure assembly (RPA), also known as a reduced pressure zone (RPZ) assembly, is a type of backflow prevention device used to protect potable water supplies from contamination or pollution caused by backflow. An RPA consists of two independently acting check valves separated by a reduced pressure zone chamber. In normal operation, the pressure in the zone between the two check valves is maintained at a level lower than the supply pressure. If the pressure in the water supply drops or if there is a backflow event, the reduced pressure zone prevents contaminants from flowing back into the potable water supply. If either of the check valves fails, the other acts as a backup to prevent backflow. RPAs are typically used in high-hazard applications where there is a high risk of contamination if backflow were to occur, such as in industrial facilities, chemical plants, and irrigation systems using fertilizers or pesticides. They are required by building codes, water purveyors and regulations to be installed in these types of systems to protect public health and safety. RPAs require periodic testing and maintenance to ensure they are functioning properly and providing adequate protection against backflow. RPAs are required to be installed with the vent a minimum of 12" above grade. These are used when the connection point of irrigation and domestic water is unknown, or when the height requirements of a PVB exceed the height limit. RPAs can be installed either at the water meter or at the connection point of domestic and irrigation water.


A pressure vacuum breaker (PVB) is another type of backflow prevention device used to protect potable water supplies from contamination or pollution due to backflow. The pressure vacuum breaker consists of a spring-loaded check valve and an air inlet valve located on the outlet side of the check valve. During normal operation, water flows through the check valve, which is open, allowing water to pass into the system. The air inlet valve is closed, preventing the entry of contaminants. However, if there is a drop in pressure in the water supply system, such as during a water main break or when there's a significant demand elsewhere in the system, the pressure vacuum breaker closes the check valve and opens the air inlet valve. This action breaks the vacuum in the system, preventing contaminated water from being siphoned back into the potable water supply. Pressure vacuum breakers are commonly used in outdoor irrigation systems, such as lawn sprinkler systems, where there is a risk of contamination from fertilizers, pesticides, or other chemicals. They are also used in other low to moderate hazard applications where there is a risk of backflow but not to the extent that would require a more complex backflow prevention device like a reduced pressure assembly. Like other backflow prevention devices, pressure vacuum breakers require periodic testing and maintenance to ensure they are functioning correctly and providing adequate protection. These are installed on the irrigation system, with a requirement of 12" above the highest irrigation head with a maximum height of 5'.

Backflow (cross-connection) case studies

Cross-connections are potential points in a plumbing system where non-potable water sources (such as industrial fluids, irrigation water, or sewage) can inadvertently come into contact with potable water. This can lead to contamination of the drinking water supply if backflow occurs. Here are a few case studies illustrating the importance of addressing cross-connections:

  1. Chemical Contamination in a Municipal Water Supply:  In a town served by a municipal water supply, a chemical manufacturing plant was located upstream from the water treatment plant. Due to a cross-connection between the plant's process water and the municipal water supply, a backflow event occurred during a maintenance operation at the plant. This resulted in toxic chemicals contaminating the town's drinking water. Several residents fell ill, and emergency measures had to be taken to provide safe drinking water while the issue was resolved. This incident highlighted the critical need for backflow prevention measures and regular inspections of cross-connections, especially in industrial areas.

  2. Fecal Contamination in a Residential Neighborhood: In a residential neighborhood, a homeowner installed a garden hose connection from their outdoor hose bib to a tank of fertilizer for their garden. The hose was left submerged in the fertilizer tank, creating a cross-connection between the potable water supply and the non-potable fertilizer solution. During a drop in water pressure caused by a water main break, the fertilizer solution was siphoned back into the home's plumbing system and contaminated the potable water supply. Several residents experienced gastrointestinal illness due to fecal contamination. This incident emphasized the importance of educating homeowners about the risks of cross-connections and the proper installation of backflow prevention devices.

  3. Irrigation System Contamination at a School: A school installed an irrigation system for its athletic fields, with connections to a nearby pond for water supply. Due to improper installation and lack of backflow prevention devices, there was a cross-connection between the pond water and the school's potable water supply. During a period of low pressure in the municipal water system, pond water contaminated with algae and sediment was drawn back into the school's plumbing system. Several students and staff members reported gastrointestinal symptoms after consuming water from the school's drinking fountains. This incident underscored the need for proper design, installation, and maintenance of irrigation systems with appropriate backflow prevention measures in place.

These case studies illustrate the potential consequences of cross-connections and the importance of implementing robust backflow prevention programs to safeguard public health and ensure the integrity of potable water supplies. Regular inspections, testing, and maintenance of backflow prevention devices are essential components of effective cross-connection control programs.

When did backflows become a requirement in Florida?

Backflow prevention regulations in Florida have been in place for several decades, but the specific requirements and enforcement mechanisms have evolved over time. The Florida Department of Environmental Protection (FDEP) and local water authorities have been instrumental in establishing and enforcing regulations related to backflow prevention to safeguard public health and protect potable water supplies. In Florida, the requirement for backflow prevention devices began to be codified in plumbing codes and regulations starting in the 1970s and 1980s. These regulations initially focused on specific high-risk industries and facilities where backflow could pose a significant threat to public health, such as hospitals, chemical plants, and large-scale irrigation systems. Over the years, the scope of backflow prevention regulations in Florida expanded to include a broader range of facilities and applications. This expansion was driven by a growing recognition of the potential risks posed by cross-connections and backflow events in various settings, including residential, commercial, and institutional properties.

The Florida Plumbing Code (adopted from the International Plumbing Code) includes requirements for backflow prevention devices in certain plumbing systems, with the specifics varying depending on factors such as the type of facility, the level of potential hazard, and local ordinances. Additionally, many municipalities and water utilities in Florida have developed their own backflow prevention programs and ordinances to supplement state regulations and address local needs and concerns. Overall, while the exact timeline may vary depending on the specific jurisdiction within Florida, backflow prevention measures have been a regulatory requirement in the state for several decades, with ongoing updates and revisions to ensure the effectiveness of these measures in protecting public health and safety.

How backflow happens:

Backflow is typically caused by one of the following reasons:

  1. Backsiphonage: This occurs when there is a sudden drop in pressure in the potable water supply system. This drop in pressure can create a vacuum effect, pulling water from a lower-pressure source (such as a connected irrigation system, chemical tank, or boiler) back into the potable water supply. Backsiphonage can happen during events like water main breaks, firefighting activities, or high demand on the water system.

  2. Backpressure: Backflow due to backpressure occurs when the pressure in the non-potable water system exceeds the pressure in the potable water system. This higher pressure forces water from the non-potable system to flow backward into the potable water supply. Backpressure can occur in situations where there's a pump, elevated storage tank, or other pressurized system connected to the plumbing network.

  3. Cross-connections: A cross-connection is a physical connection between the potable water supply and a non-potable water source or system. If backflow occurs in the non-potable system, contaminants can be siphoned or pushed back into the potable water supply through the cross-connection. Cross-connections can occur in various settings, including residential, commercial, industrial, and agricultural facilities.

  4. Improper plumbing configurations: Poorly designed or improperly installed plumbing systems can create conditions conducive to backflow. For example, a garden hose submerged in a pool, bucket, or chemical container can create a cross-connection, allowing water or chemicals to flow back into the plumbing system if pressure conditions change.

Backflow testing requirements:

Backflow testing requirements vary depending on local regulations, plumbing codes, water purveyors and the type of facility or system involved. However, there are some common principles and practices associated with backflow testing requirements:

  1. Regulatory Compliance: Many jurisdictions have specific regulations and ordinances regarding backflow prevention and testing. These regulations often stipulate the types of facilities or systems that require backflow prevention devices and the frequency of testing. Regulations may also specify the qualifications and certification requirements for individuals conducting backflow testing.

  2. Frequency of Testing: Backflow prevention devices typically require periodic testing to ensure they are functioning correctly and providing adequate protection against backflow. The frequency of testing varies depending on factors such as the type of device, the level of risk, and regulatory requirements. In many cases, annual testing is required, but for high-risk facilities or critical systems, more frequent testing may be necessary. In Central Florida backflows are required to be tested either every year or every other year depending on the requirements set by the water purveyor.

  3. Qualified Testers: Backflow testing must be conducted by qualified individuals who have been trained and certified in backflow prevention testing procedures. Certification requirements may be established by state or local authorities or by industry organizations such as the American Society of Sanitary Engineering (ASSE) or the American Backflow Prevention Association (ABPA). At ServiceOne, Tom Geromanos, our plumbing manager as well as a licensed plumbing contractor also holds backflow testing and repair certifications.

  4. Documentation: After testing, a certified tester typically completes a test report documenting the results of the backflow test. This report may include details such as the date of the test, the location of the device, test results, any repairs or adjustments made, and the signature of the tester. Copies of test reports are submitted to the appropriate water purveyor and customer for review and record-keeping purposes.

  5. Repair and Maintenance: If a backflow prevention device fails the test or is found to be malfunctioning during testing, it must be repaired or replaced promptly to ensure continued protection against backflow. Qualified technicians should perform any necessary repairs or maintenance in accordance with manufacturer specifications and industry best practices. Certain types of backflows are not permitted to be repaired and must be replaced.

  6. Record-Keeping: Records of backflow testing, repairs, and maintenance activities should be kept on file for inspection by regulatory authorities. These records help demonstrate compliance with backflow prevention requirements and provide a historical record of the maintenance history of backflow prevention devices.

It's important for property owners, facility managers, and plumbing professionals to familiarize themselves with the specific backflow testing requirements applicable to their jurisdiction and to ensure compliance with those requirements to protect public health and safety.


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