Common Questions

Last updated Nov. 22, 2016 - 3:03 pm

Below are some common questions we receive about cross connections.

What is a cross connection?

A cross-connection is any temporary or permanent connection between a public water system or consumer's potable water system (drinking water) and a source or system containing non-potable water or other substances.

Common residential examples of cross connection hazards (source of contamination) that need to be protected with a backflow preventer:

  • Fire sprinkler system
  • Lawn irrigation systems
  • Auxiliary water supply (wells)
  • Hot tubs / Spas
  • Swimming Pools
  • Hose bibs / Garden hose
  • Boilers

What is backflow or a containment backflow assembly?

Backflow is the undesirable flow reversal of water, liquids, gases or other substances into the City of Raleigh Public Water Supply.

Backflow can occur when water pressure in the distribution system drops relative to a service line. This can happen due to the use of hydrants for fire fighting, water main break, high usage, or backpressure from a pump.

A backflow assembly is an assembly that allows water to travel in only one direction. When working properly it stops a contaminant such as pesticides, fertilizers or animal waste from entering the potable water supply when either a backsiphonage or backpressure event occurs. A reduced pressure assembly (RPZ) is required for both residential lawn irrigation systems and when a resident uses public domestic service while also having a private irrigation well within the property limits.

A containment assembly is the first backflow after the water/irrigation meter or fire service line, with no unprotected taps before the backflow assembly.

I have a backflow assembly. How can I verify this is the containment assembly?

Slowly close the shut off valve to the backflow assembly. Check to see if water is still being supplied to the fixtures connected to the water service by slowly turning on faucets, irrigation systems, flushing toilets, etc. If the fixtures continue to have water flowing, then you do not have the proper backflow protection. If water flow stops, you are properly contained with a backflow assembly.

Who is required to have a backflow assembly?

In the City of Raleigh's Public Utilities Cross Connection Ordinance, Section 8-2147 & 8-2148 requires every residential and commercial water consumer to have a containment assembly or device installed at each point of separation between the public water supply and a private service or private distribution system or at the point of metering. For residential customers without an irrigation or fire sprinkler system or any hazard listed in Sec. 8-2147, this containment is accomplished by the dual check that is installed on the meter yoke. All other services are required to be contained by the installation of an approved Reduced Pressure Zone (RPZ) backflow assembly or Double Check Valve Assembly (DCVA) after the meter or point of separation. Backflow protectin is required for all services and facilities are not exempted because of the age of the facility.

Our Public Utilities Department will be conducting surveys at each commercial facility to verify there are approved backflow assemblies containing each domestic, irrigation, and fire sprinkler service.

Your facility may be found to not have the proper backflow protection, and a letter will be given to you to install an approved backflow. For more information on the requirement to install a backflow assembly you may email us at or call 919-996-2742

Why does the backflow assembly need to be tested?

A backflow assembly is a mechanical assembly that is subject to failure. It is impossible to tell if it is working by appearance only. An operational test using a differential gauge is required to determine if the backflow is working properly.

When am I considered in compliance?

Compliance is met when you have your backflow tested by a City of Raleigh Certified Tester and that passing operational test report has been submitted to the Cross Connection Program.

Commercial backflows are to have a passing test report submitted annually.

Residential irrigation backflows are to have a passing test report submitted tri-annually.

What do I do if my backflow assembly fails a test?

A failed assembly will need to be cleaned, repaired or in some cases it may need to be completely replaced. After cleaning, repair or replacement a successful re-test needs to be performed and turned into the Cross Connection Control Program within 15 days.

Who pays for this test?

Installation of a backflow assembly is required by the NC Plumbing Code and therefore is installed on private property. Raleigh City Code defines the consumer as the responsible party to maintain and test their assembly. (Raleigh City Code 8-2154)

Does the city provide testing service?

No. The City maintains a list of testers certified to work within the Raleigh water system. A tester is required to maintain a certification from a locally approved certification school, obtain annual calibration for a differential or electronic test kit, and other requirements as required by the Director of Public Utilities. Testers who do not meet these requirements are removed from the list until they have met all requirements.

Who Can Install, Repair, and Replace a backflow assembly?

Licensed Class I Plumber: can install, replace, or repair irrigation, domestic, and fire backflow assemblies for all structures.

Licensed Class II Plumber: can only install, replace, or repair irrigation, domestic, or fire backflow assemblies for single-family residential dwellings.

Licensed Fire Sprinkler Contractors: can only install, replace, or repair backflow assemblies that are a part of the fire sprinkler system. They cannot install, replace, or repair irrigation or domestic backflow assemblies.

Licensed Utility Contractor: can install, replace, or repair irrigation, domestic, and fire backflow assemblies within 5' of the building.

Restricted Limited Plumbing Contractor License: can install, repair or replace exterior backflow assembly connected to water service piping two inches in diameter or less.

Notes from City of Raleigh's Cross Connection Program: A City of Raleigh Certified Tester is allowed to test any backflow in our water service area. All installations, replacements, and repairs of backflow assemblies must be performed by an approved licensed plumber or contractor.

Do I need a permit?

New Installation: Yes, a permit is required when installing a new backflow assembly.

City of Raleigh: Yes
Wake Forest: Yes
Garner: Yes
Wake County: No

Replacing or Relocating a Containment Assembly: Yes, a permit is required when replacing or relocating a backflow assembly.

*Inspection Departments:
City of Raleigh: 919-996-2495
Wake County (Zebulon, Rolesville, Knightdale, Wendell): 919-856-6222
Town of Wake Forest: 919-435-9530
Town of Garner: 919-773-4433

Do I have to obtain an operational test for a newly installed backflow assembly?

Yes. Backflow assemblies may be subjected to environmental conditions that could cause wear or deterioration to the seals and parts of the assembly prior to installation.

Information for completing the Backflow Assessment and Verification Forms

Company Name: This information can be found on the customer's utility bill or Wake County Real Estate Data (
Found on customer's utility bill
Property Location Address:
Found at Wake County Real Estate Data
Found at Wake County Real Estate Data
Facility Use:
To be completed by a licensed plumber, professional engineer, or certified tester
Backflow information:
Found on the assembly. To be completed by licensed plumber, professional engineer, or certified tester

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