Backflow Construction Guide

All industrial and commercial customers are required by ordinance to install and maintain backflow prevention assemblies at every water service connection to Charlotte Water. This includes domestic, irrigation, fire line services, and swimming pool meters.

Before beginning any construction project, industrial and commercial customers must submit construction plans to Mecklenburg County Land Use and Environmental Services. There, Charlotte Water will evaluate your plans and inform you of the requirements for a backflow device.

When the backflow prevention assembly is installed, call Charlotte Water Backflow at 704-336-2456 to request an inspection. A Charlotte Water approved and certified tester must test the device upon installation and annually thereafter.

Approval Procedures for CLTWater

Required Backflow Preventer Installations

PRIOR TO INSTALLING A CLTWater‐REQUIRED BACKFLOW PREVENTER, THE DESIGNER AND/OR INSTALLER MUST OBTAIN CLTWater APPROVAL OF THE INSTALLATION PLAN

(Designer And Installer Must Be Currently Licensed By The Appropriate State Of North Carolina Licensing Board):

  1. Complete a CLTWater “Backflow Service Application” (BSA).  Be sure to provide all information listed in the form.  Failure to do so may delay approval.
  2. Submit the BSA, along with any required plan information*, to the Commercial Counter at Building Standards (2145 Suttle Ave., Charlotte, NC  28208‐5237).    

    *Note: Some projects may not require drawings for review, but may instead be managed via on‐site assistance from a CLTWater Backflow Prevention Construction Inspector.  The designer and/or contractor is responsible for contacting CLTWater to determine whether or not submittal of plan drawings is required.  All locations for CLTWater backflow preventers require CLTWater approval prior to installation.

  3. Plan review is handled via the Building Standards’ commercial plan review process.  All drawing submittals must conform to CLTWater’s Backflow Prevention Plan Submittal Requirements list, unless instructed otherwise.  Revise and resubmit plan drawings per plan review comments as needed.
  4. Wait for CLTWater approval of your BSA and plan before beginning the installation.  Approved plan drawings will be stamped by CLTWater as such.  Projects managed via site assistance will receive an approval notice from the Backflow Prevention Construction Inspector.  The designer and/or installer shall be responsible for obtaining approvals required by all other agencies.

INSTALLER MUST OBTAIN FIELD APPROVAL OF THE INSTALLATION FROM A CLTWater BACKFLOW PREVENTION CONSTRUCTION INSPECTOR PRIOR TO PLACING THE WATER SYSTEM IN SERVICE

(Certain Exceptions Will Be Allowed for Retrofit Projects at Existing Facilities):

  1. Call the Backflow Construction Inspector to resolve any problems encountered in the field.  Installing backflow preventers in a location and/or manner other than that specified on the plans approved by CLTWater requires approval from the Inspector.  Obtain site assistance by calling 704‐391‐5188.
  2. Obtain approval of the installation(s) by calling 704‐391‐5188 to request inspection.  Inspection service will be provided within three working days from the date of request. Approval by the Backflow Inspector is required prior to issuance of the Certificate of Occupancy (CO).
  3. Verify installation approval by contacting the Inspector or by calling 704‐391‐5188.  Correct all deficiencies per Inspector’s instructions and obtain reinspection and inspection results as above. CLTWater is not responsible for delay of CO issuance when procedures above are not followed.  
  4. Prior to placing the water system(s) in service, have the backflow preventer(s) tested ASAP and submit a copy of the test report(s) to CLTWater within 10 days of the Inspector’s approval of the installation.

Guide for Determining What Type Backflow Preventer Charlotte Water (CLT Water) Will Require

Irrigation Systems

As of March 24, 2003, all irrigation systems now require a Reduced Pressure Principle Assembly (RP). Irrigation systems with a Double Check Valve Assembly (DCVA) that has been previously approved and inspected by CLT Water are “grandfathered” until such time that the DCVA needs replacement.

Fire Protection Systems

Characteristics That Require Installing a Reduced Pressure Principle Assembly (RP):

(1) presence of a Fire Department Connection (FDC)

(2) chemicals (glycol or other types) added to the water in any part of the system,

(3) system involving a water storage facility (ex.: above- or below-ground tanks, surface reservoirs),

(4) back-up provision for using an auxiliary water source (ex.: private well, pond, river).

Note: State and local Codes do not allow a private system to be served by an auxiliary water source while connected to CLT Water’s public water system. An air gap separation must be maintained.

Characteristics That Require Installing a Double Check Valve Assembly (DCVA) (Minimum Protection):

(1) system not involving any characteristics for which CLT Water requires an RP,

(2) system carrying only air (“dry system”),

Domestic, Process, and Combination Systems

Characteristics That Require Installing a Reduced Pressure Principle Assembly (RP):

(1) system involving any of the characteristics listed above for which CLT Water requires an RP,

(2) system with any type booster pump or pressure washer equipment

(3) system involving any piping at an elevation which is greater than fifty (50) feet above the meter piping,

(4) system which involves water that has been or is being recirculated (ex.: boiler, chiller, machinery cooling)

(5) system used for chemical mixing or chemical feed activities (ex.: golf course operations, industrial processes),

(6) system involving tanks, lines, steam boilers, or vessels that carry sewage, toxic, or radioactive substances.

(7) system which involves injection or aspiration of chemicals into any portion of the system (ex.: sanitizer system at multi-compartment sink, fertigation system)

(8) system with sewage pump or water-operated sewage sump ejector

(9) system with any non-potable branch or connected to any equipment serving a non-potable function (ex.: irrigation branch, decorative water features (fountain, waterfall, etc.), parts washer).

(10) back-up provision for using an auxiliary water source (ex.: private well, pond, river),

Note: State and local Codes do not allow a private system to be served by an auxiliary water source while connected to CLT Water’s public water system. An air gap separation must be maintained.

Characteristics That Require Installing a Double Check Valve Assembly (DCVA) (Minimum Protection):

(1) system not involving any characteristics for which CLT Water requires an RP

Types of Facilities That Require Installing a Reduced Pressure Principle Assembly (RP)

Facilities listed here may not necessarily involve any of the aforementioned water system characteristics, but are required to install an RP on their domestic, process, and combination systems due to the type of activities and/or materials used in the facilities and their potential to create a health hazard.

(1) Battery manufacturer

(2) Brewery, dairy, or bottling plant

(3) Buildings with any tenant occupancy

(4) Cannery

(5) Carwash

(6) Chemical processing plant

(7) Dental service of any type

(8) Dry cleaners

(9) Dye works

(10) Exterminating company

(11) Film lab

(12) Grocery store with injection or aspiration of chemicals into a portion of the system (ex.: sanitizer system in meat department)

(13) Hospital, medical office, or health service facility of any type

(14) Laboratory

(15) Laundry (commercial) – except if only self-service

(16) Lawn-care service, fertilizer plant

(17) Metal plating or processing facility

(18) Morgue, mortuary

(19) Nursing home, including “assisted living” facilities

(20) Pharmaceutical plant

(21) Power plant

(22) Sewage collection or treatment facility

(23) Swimming pool – except those excluded by Sec. 23-113

(24) Tire manufacturer

(25) Veterinary service of any type (ex.: hospital, clinic, or office)

(26) Water-front facilities (ex.: boat dock, marina)

(27) Any facility or system, which is insufficiently accessible for inspection by a CLT Water backflow inspector

Types of Facilities That Require Installing a Double Check Valve Assembly (DCVA)

(Minimum Protection):

Facilities listed here cannot involve any of the aforementioned water system characteristics nor facility types for which CLT Water requires an RP.

(1) Distillery

(2) Gas station

(3) Mobile home park

(4) Restaurant without injection or aspiration of chemicals into a portion of the system (ex.: sanitizer system at multi-compartment sink)

(5) Self-service laundry

(6) Other facilities for which no other assembly is otherwise specified

Note: each private water system will be evaluated on a case-by-case basis. In some cases, the requirement may differ from this list.

Backflow Construction Design Specifications

Reduced Pressure Principle Assemblies

Double Check Valve Assemblies

Test Equipment and Schools

Approved Backflow Prevention Assembly Testing Equipment

Manufacturer Model
Duke E-Z 900
Barton/Cameron M247
Midwest Instrument 830
Midwest Instrument 835
Midwest Instrument 845
Watts TK-DL
Watts TK-99D
Apollo 40-200-TK3U
Apollo 40-200-TK5U
 Arbiter's Mako Test Gauge MK2
 Arbiter's Mako Test Gauge MK3 
 Arbiter's Mako Test Gauge MK5

 

Approved Backflow Testers Schools

Central Piedmont Community College

Central Piedmont – Continuing Education

 PO Box 35009

 Charlotte, NC 28235

 Registration: Students can Contact CP at (704) 330‐4223

Charlotte Water

Engineering Div. Installations and Development Services ‐

Backflow Prevention

2145 Suttle Av.

Charlotte, NC 28208

(704) 391‐5188

USC Foundation Office

Research Annex 219

Los Angeles, CA 90089‐7700

Office: 866.545.6340

Fax: 213.740.8399

Email: fccchr@usc.edu

University of Florida Center for Training Research and Education for Environmental Occupations (TREEO)

Backflow Prevention & Cross Connection Programs

Office of Professional and Workforce Development

3900 SW 63rd Boulevard | Gainesville, FL 32608

Direct: 352.294.3878 | Main: 352.392.9570

NC Rural Water Association

P.O. Box 540

Welcome, NC 27374

Training Location: 907 Fields Dr, Sanford, NC

Mr. Mac Merritt, Backflow & Cross Connection Training Specialist

Fax: 336‐731‐8589

Office: 336‐731‐6963

Mobile: is 336‐590‐2020

www.ncrwa.com see training

City of Durham

Department of Water Management

101 City Hall Plaza, Durham, NC 27701

Phone: 919‐560‐4194 [Ext. *35249]

Email: CCCProgram@durhamnc.gov

Greenville Utilities Commission

Water Resources Department

P O Box 1847

Greenville, NC 27835

Mrs. Deanna Castellow, Backflow Coordinator

backflow@guc.com

(252) 551‐1551

City of Raleigh

3304 Lake Woodard Dr

Raleigh, NC 27604

Ms. Joanie Hartley

(919) 996‐2747, email: cross.connection@raleighnc.gov

Drain Port Requirements for Covers Over Reduced-Pressure Principle Assemblies

Covers (enclosures) installed over reduced-pressure principle assemblies (RP) must include weather-proof drain ports sufficiently sized to handle a full-flow discharge. The minimum total area of the drain port opening(s) is to be no less than that of the drain size required for an indoor installation; see the chart below for minimum drain port sizes. Rectangular or circular openings are acceptable; typical dimensions are shown below. Note that a minimum elevation difference of 6" must be maintained between the RP's discharge outlet and the top of all drain ports.

 RP SIZE MINIMUM TOTAL AREA OF DRAIN PORT(S) TYP. SIZE FOR RECTANGULAR OPENING (IN.) TYP. #&SIZE FOR CIRCULAR OPENING(S) (DIA.)
3/4" - 1" 12.5 SQ. IN. 2 1/2 h X 5w 1 - 4"
1 1/2" - 2" 20 SQ. IN.  3h X 6 1/2 w 2 - 4"
2 1/2" - 3"  28 SQ. IN. 4h X 7w 3 - 4"
4" - 6"  50 SQ. IN. 5 h X 10w 4 - 4"
8" - 10" 100 SQ. IN.  5h X 20w (do rectangular)

 

* When necessary to install 2 or more drain ports, they should be installed together on the same side of the enclosure so as to avoid creating the opportunity for cross drafts.

* Other installation requirements and standard details can be obtained from CLTWater.

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