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WQD | SDW — Backflow Prevention & Cross-Connection Control

Safe Drinking Water Section

Backflow Prevention and Cross-Connection Control

Revised On: Jul. 17th, 2024 - 02:16 pm

Posted On: July 9, 2024 - 7 p.m.

Arizona’s Administrative Code establishes standards and guidelines for backflow prevention and cross-connection control | See A.A.C. R18-4-215 >

What is Backflow?

Backflow is a reverse flow condition that can cause water or mixtures of water and other substances to be pulled back into a water distribution system. Without proper protections, backflow can cause unwanted substances to enter systems that distribute otherwise safe drinking water. Backflow conditions can be created by a difference in water pressure (backpressure), a vacuum (backsiphonage), or a combination of both.

What is Backflow Prevention?

Backflow prevention safeguards against backflow conditions, either by a mechanical device known as a backflow-prevention assembly or by an air-gap that renders backflow impossible.

When is a Backflow-Prevention Assembly Needed?

Public water systems are required to protect their systems from backflow conditions wherever there is an unprotected cross-connection that could lead to the contamination of the water in the distribution system. Examples of these cross-connections include:

  • Locations where substances that are harmful to public health could enter a public water system via backflow.
  • Locations where water that is not accepted as an additional source by ADEQ or the public water system could enter a public water system via backflow.
  • Locations where there is a significant possibility that a cross-connection problem will occur.

Approved Backflow-Prevention Assemblies

There are several types of backflow-prevention assemblies that may be required. All devices must be testable in order to meet ADEQ standards. Listed in decreasing order of the level of protection that they provide, those assemblies are as follows:

An air-gap is not a physical assembly but is instead a vertical separation between a water supply and the open vessel that it is flowing into. An air-gap must be at least twice the diameter of the supply pipe, with a minimum distance of one inch.

RP assemblies contain two independently acting check valves together with a hydraulically operating, mechanically independent pressure differential relief valve located between the check valves and below the first check valve. The unit must include test cocks and shut-off valves at each end of the assembly. This assembly type cannot be used for backflow prevention of sewage or reclaimed water.

PVB assemblies contain an independently operating check valve and an independently operating air inlet valve located on the discharge side of the check valve. The assembly must be equipped with test cocks and tightly closing shutoff valves attached at each end of the assembly.

DC assemblies contain two independently acting check valves and shutoff valves attached at each end of the assembly and fitted with test cocks 

Revised On: Jul. 17th, 2024 - 02:16 pm

Backflow-Prevention Assembly Testing

All required backflow-prevention assemblies must be tested at least annually by a certified backflow tester. Backflow tester certifications must be obtained through an ADEQ-approved authority:

Backflow Prevention Certifications

There are two different types of certifications related to backflow prevention | See A.A.C. R18-4-215 (E) >

  • “General” Backflow Testers — This certification is needed when conducting required backflow-prevention assembly tests. The required tests are performed annually and after the installation, relocation, or repair of a required backflow-prevention assembly.
  • Cross-Connection Control Program Specialists — This certification is needed for individuals with a direct responsibility for implementing a backflow prevention program for a water system that is serving more than 50,000 people.

Certifications for “General” Backflow Testers and for Cross-Connection Control Program Specialists must be obtained through certifying authorities that have been approved by ADEQ.

 

The following organizations offer certification examinations and are approved as certifying authorities by ADEQ:

  • The California-Nevada Section of the American Water Works Association (CA-NV Section AWWA)
    • Backflow “General” Tester Certifications | View >
    • Cross-Connection Control Program Specialist Certifications | View >
  • The American Backflow Prevention Association (ABPA)
    • Backflow “General” Tester Certifications | View >
    • Cross-Connection Control Program Specialist Certifications | View > 
  • The American Society of Sanitary Engineers – Affiliated with the International Association of Plumbing and Mechanical Officials (ASSE – Affiliated with IAPMO)
    • Backflow “General” Tester Certifications | View >
    • Cross-Connection Control Program Specialist Certifications | View >
  • All American Backflow Prevention (AABP)
    • Backflow “General” Tester Certifications | View >