Residential plumbing services

RPZ Testing & Installation

RPZ testing and installation refer to services related to Reduced Pressure Zone (RPZ) assemblies, which are crucial components in backflow prevention systems. Backflow occurs when contaminated water flows backward into the public water supply, posing health risks. RPZ assemblies prevent this by maintaining a higher pressure in the water supply than in potential contamination sources.


RPZ Testing

Inspection and Testing: Trained professionals conduct regular inspections and testing of RPZ assemblies to ensure they are functioning correctly. This involves checking for any signs of wear, damage, or malfunction that could compromise the assembly's ability to prevent backflow.


Pressure Differential Check: During testing, the technician measures and verifies the pressure differential across the RPZ assembly. This ensures that the assembly is maintaining the necessary pressure to prevent backflow. If any issues are detected, adjustments or repairs may be necessary.


Visual Inspection: Technicians visually inspect the entire RPZ assembly, checking for physical damage, corrosion, or any signs of wear. The visual inspection is crucial for identifying potential problems that may not be immediately apparent during pressure testing.


Documentation and Certification: After a successful RPZ test, the technician provides documentation and certification, indicating that the assembly is in compliance with local regulations and is effectively preventing backflow. This documentation is often required for regulatory compliance

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RPZ Installation


Site Assessment: Before installation, a site assessment is conducted to determine the optimal location for the RPZ assembly. Factors such as proximity to potential contamination sources and accessibility for maintenance are considered.


Compliance with Regulations: RPZ installations must adhere to local building codes and regulations. Professionals ensure that the installation meets these requirements to guarantee the proper functioning of the backflow prevention system.


Assembly Selection: Different RPZ assemblies are designed for specific applications. The selection of the appropriate assembly depends on factors such as the degree of hazard, flow rates, and local regulations. The installation professional helps determine the right assembly for the specific site.


Connection to Water Supply: The RPZ assembly is connected to the water supply line, typically after the water meter and before any branching lines. This strategic placement ensures that the assembly can effectively prevent backflow from potential contamination points.


Testing and Certification: After installation, the RPZ assembly undergoes initial testing to ensure proper functionality. Once the assembly passes the testing phase, the installation is certified, and documentation is provided to verify compliance with backflow prevention regulations.



RPZ testing and installation are critical components of maintaining a safe and uncontaminated water supply. Regular testing and compliance with local regulations are essential to ensure that RPZ assemblies effectively prevent backflow and protect public health.

rpz testing & installtion faqs

  • What is the purpose of RPZ testing, and how often should it be conducted?

    RPZ testing is essential to ensure that Reduced Pressure Zone assemblies are functioning correctly, preventing backflow and protecting the water supply from contamination. Testing should be conducted annually or more frequently, as required by local regulations, to maintain compliance and ensure ongoing effectiveness.

  • Why is backflow prevention necessary, and how does an RPZ assembly work?

    Backflow prevention is necessary to safeguard the public water supply from contamination. An RPZ assembly works by creating a physical barrier that prevents water from flowing backward into the main water supply. It maintains a higher pressure in the water supply than in potential contamination sources, ensuring that water flows only in the desired direction.

  • What are the common signs that an RPZ assembly may be malfunctioning?

    Signs of a malfunctioning RPZ assembly include water leaks, unusual noises, or a decrease in water pressure. Visual inspections may reveal physical damage, corrosion, or other issues. If property owners notice any of these signs, it's crucial to contact Credence Plumbing. 

  • Can I install an RPZ assembly myself, or is professional installation required?

    RPZ assembly installation should be carried out by licensed professionals with expertise in backflow prevention systems. Proper installation is essential to ensure compliance with local regulations and the effective functioning of the assembly. Attempting to install an RPZ assembly without the necessary expertise can lead to safety hazards and regulatory non-compliance.

  • What are the consequences of not maintaining or testing RPZ assemblies regularly?

    Neglecting regular maintenance and testing of RPZ assemblies can lead to their malfunction. If an RPZ assembly fails, there is an increased risk of backflow, potentially contaminating the public water supply. Non-compliance with testing requirements may result in regulatory penalties, fines, and, in severe cases, water service disconnection. Regular testing and maintenance are critical for public health and regulatory adherence.