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Backflow Guidelines, Installation Standards & Specifications

Adapted from the City of Fort Worth Ordinance 12274

Schematic Diagram

Backflow Example 1 <img src=”http://fortworthtexas.gov/uploadedImages/Water/backfl2.jpg” width=”244”height=”169” alt=”Backflow Example 2” align=”left” vspace=”5” hspace=”5”> Backflow Example 3

A. Introduction

Pursuant to Title 30, Texas Administrative Code, Section 290.44, it is the responsibility of the City of Fort Worth to protect its drinking water supply by instituting and enforcing a cross connection program. The program includes the installation of backflow prevention assemblies where deemed appropriate or necessary.

It is a logical assumption that because water is always under pressure, it can only flow in one direction. However, it is possible for the flow to be reversed. Water will always flow towards the point of lowest pressure. If a main line in our system should break, or if a fire occurred and the fire department opened several hydrants, the pressure in our water mains could drop dramatically, causing a reversal of flow. The potential for this reversal of flow is why our department is concerned about the possibility of backflow of contaminants into our water system.

Key definitions

CROSS CONNECTION is any physical arrangement where a public water system, such as the City of Fort Worth, is connected directly or indirectly with any other apparatus that may cause any substance, other than the city’s drinking water, to enter the drinking water system. BACKFLOW means the flow in the direction opposite to the normal flow or the introduction of any foreign liquids, gases, or substances into the water distribution system. Some cross connections are necessary and cannot be eliminated. Therefore, appropriate isolation methods and assemblies must be employed to protect against the potential of a backflow incident.

B. Applicability

As a condition of water service, all customers shall install, maintain, and operate their piping and plumbing systems in accordance with the City’s Plumbing Code and its Environmental Protection and Compliance Ordinance #12274. If there is a conflict between this guidance document and these codes, the more restrictive provision shall apply.

C. Circumstances Requiring Use of Backflow Assemblies

At a minimum, a backflow prevention assembly will be required in each of the following circumstances:

  1. When the nature and extent of any activity at a premise, or the materials used in connection with any activity at a premise, or materials stored at a premise, could contaminate or pollute the potable water supply.
  2. When a premises has one or more cross connections.
  3. When internal cross connections are present that are not correctable.
  4. When intricate plumbing arrangements are present that make it impractical to ascertain whether cross connections exist.
  5. When a premises has a repeated history of cross connections being established or re-established.
  6. When entry to a premise is unduly restricted so that inspections for cross connections cannot be made with sufficient frequency to assure that cross connections do not exist.
  7. When materials are being used such that, if backflow should occur, a health hazard could result.
  8. When installation of an approved backflow prevention assembly is deemed by an Inspector to be necessary to accomplish the purpose of these regulations.
  9. When an appropriate cross connection survey report form has not been filed with the Director.
  10. When a fire sprinkler system using non-potable piping material is connected to the City’s water system.
  11. In all new nonresidential construction there shall be installed an approved backflow assembly at the service connection. The type of the assembly will be commensurate with the degree of hazard as determined by an Inspector.
  12. When a building is constructed on commercial premises, and the end use of such building is not determined or could change, a reduced pressure principle backflow prevention assembly shall be installed at the service connection to provide protection of the public water supply in the event of the most hazardous use of the building.
  13. If a premises is required to have backflow prevention assemblies, but water cannot be turned off during the testing of such assemblies, the premises shall be equipped with dual backflow prevention assemblies of the same type so that testing, repair and maintenance can be performed.
  14. Any used water return system that has received approval from the Director.
  15. If a point-of-use assembly has not been tested or repaired as required by this Division, a premise isolation assembly shall be required.
  16. If a Backflow or Plumbing Inspector determines that additions or rearrangements have been made to the plumbing system without the proper permits as required by the Plumbing Code, premise isolation shall be required.
  17. All multistory buildings or any building with a booster pump or elevated storage tank.
  18. Retrofitting shall be required on all health hazard connections and wherever else the Director deems retrofitting necessary. (No “Grand fathering” for health hazards – ever.)
  19. Any premises requiring multiple service connections for adequacy of supply and/or fire protection shall have a backflow assembly on each service connection. The assembly shall be commensurate with the degree of potential hazard that could occur in the event of an interconnect between any of the buildings on the premises.

D. Installation Specifications

Backflow prevention assemblies shall be installed in accordance with the Plumbing Code and this Division. The assembly installer shall obtain the required plumbing permits prior to installation and shall have the assembly inspected by a certified cross connection inspector and as required by the Plumbing Code.

  1. No part of a reduced pressure principle backflow prevention assembly shall be submerged in water or installed in a location subject to flooding. All assemblies installed below grade shall have non-ferrous threaded plugs inserted in the test ports.
  2. Assemblies shall be installed at the point of delivery of the water supply, before any branch in the line, and on private property located just inside the boundary of the City’s right-of-way. An Inspector may specify other areas for installation of the assembly. The assembly shall be protected from freezing and other severe weather conditions.
  3. All vertical installations shall be approved, in writing, prior to installation and all vertical installations must be of an assembly approved by USCFCCCHR.
  4. The assembly shall be readily accessible with adequate room for maintenance and testing. Assemblies two (2) inches and smaller shall have at least a six (6) -inch clearance on all sides of the assembly. All assemblies larger than two (2) inches shall have a minimum clearance of twelve (12) inches on the back side, twenty-four (24) inches on the test cock side, twelve (12) inches below the assembly and thirty-six (36) inches above the assembly.
  5. If the Director grants written permission to install the backflow assembly inside of a building, the assembly shall be readily accessible between 8:00 a.m. and 5:00 p.m., Monday through Friday.
  6. If an assembly is installed pursuant to Ordinance 12274 12.5-531, subsection (a)(8), and is four (4) inches or larger and is installed five (5) feet or higher above the floor, it shall be equipped with a rigidly and permanently installed scaffolding acceptable to the Director. This installation shall also meet all applicable requirements set out by the U.S. Occupational Safety and Health Administration and the State of Texas occupational safety and health laws.
  7. RP assemblies may be installed in a vault only if relief valve discharge can be drained to daylight through a bore sight type drain. The drain shall be of adequate capacity to carry the full rated flow of the assembly and shall be screened on both ends.
  8. An approved air gap shall be located at the relief valve orifice of RP assemblies. This air gap shall be at least twice the inside diameter of the incoming supply line as measured vertically above the top rim of the drain and in no case less than one (1) inch.
  9. All assemblies installed in a vault that is 5 ft. from finish floor to top of lid must have a permanently installed ladder.
  10. Vaults must have BILCO type J, JD or equivalent. Vaults in high traffic areas must have BILCO type HLC or equivalent

Table D-1, Required - Point of Use (Internal) Protection Systems

Trap primers Point of Use
Aspirator (medical) Health
Bedpan Washers Health
Autoclaves Health
Specimen tanks Health
Sterilizers Health
Cuspidors Health
Lab Bench equipment Health
Autopsy and mortuary equipment Health
Sewage pump Health
Sewage ejectors Health
Fire-fighting system w/chemical introduction Health
Connection to sewer pipe Health
Connection to plating tanks Health
Irrigation systems with chemical additives or agents Health
Connection to salt-water cooling system Health
Tanks, vats or other vessels containing toxic substances Health
Connection to industrial fluid systems Health
Dye vats or machines Health
Cooling towers with chemical additives Health
Trap primer Health
Steam generators Health
Heating equipment Commercial or Domestic Health
Irrigation systems (no chemical injection) Non-health
Swimming pools Public or Private Health
Carbonated Drink Dispensers w/pump Health
Ornamental fountains Health
Degreasing equipment Non-health
Lab bench equipment Non-health
Hose bibs> Non-health
Trap primers Non-health
Flexible shower heads Non-health
Steam tables Non-health
Washing equipment Non-health
Shampoo basins Non-health
Kitchen equipment Non-health
Aspirators Non-health
Domestic space-heating boiler Non-health

AVB designations assume no downstream valving and no constant pressure. All assemblies must be installed according to City of Fort Worth Ordnance (i.e., AVB’s and PVBs are for protection against backsiphonage only; AVBs may not be installed under constant pressure or with downstream valves. AVBs and PVBs must be installed with appropriate clearances above downstream piping [12” for PVBs, 6” for AVBs.)

Table D-2, Required Premises Isolation (Reprinted from AWWA Manual M-14)

Description of Cross Connection Hazard Recommended Assembly
All New, Non-residential Construction Non-Health DC
Hospitals, mortuaries, clinics, laboratories Health RPZA
Plants using radioactive material Health RPZA
Petroleum processing or storage facilities Health RPZA
Premises where inspection is restricted Health RPZA
Sewage treatment plant Health RPZA
Sewage lift stations Health RPZA
Commercial laundry Health RPZA
Plating or chemical plants Health RPZA
Docks and dockside facilities Health RPZA
Food and beverage processing plants Health RPZA
Pleasure-boat marina Health RPZA
Tall Buildings (protection against excessive head of water Non-Health RPZA, DC
Steam Plants Non-Health RPZA
Reclaimed water systems Health RPZA

Notes:

AG = Air gap DC = Double Check Valve Backflow-prevention assembly AVB = Atmospheric Vacuum Breaker RPZA = Reduced-pressure principle Backflow prevention-assembly PVB = Pressure Vacuum Breaker

E. Special Considerations

Thermal expansion It is the responsibility of the property owner to eliminate the possibility of thermal expansion, if a closed system has been created by the installation of a backflow assembly.

Pressure Loss

Any water pressure drop caused by the installation of a backflow assembly shall not be the responsibility of the City. The Department may give reasonable assistance to a property owner regarding information on adequate sizing of assemblies and proper plumbing practices to provide for required pressure and flows for fire protection.