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The City of Portland, Oregon

Portland Water Bureau

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Installation Requirements

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Backflow assembly installation requirements (basic installation criteria)

1.  Premises-Isolation assemblies (those that directly protect the public water supply) must be installed on private property at the property line adjacent to the water service connection to the premises and be compliant with all applicable criteria stated herein. The supply side of premises-isolation assemblies must be plumbed with potable water piping and fittings meeting current NSF/ANSI standards for lead content. Premises-Isolation assemblies installed in buildings that extend beneath the right-of-way must be installed at the point where the water service enters the open space and be compliant with all other applicable installation criteria stated herein. On a case-by-case basis with prior Water Bureau approval and provided there are no Oregon Administrative Rules (OAR) Table 42 conflicts, a domestic Premises–Isolation backflow assembly may be installed at a point prior to any piping branches and/or run of exposed piping in the plumbing system as opposed to immediately at the service connection to the premises.  Point-of-Use assemblies (those installed on piping branches, i.e. irrigation systems, process water, etc.) must be installed on private property in conformance with the local plumbing code. Only approved Double Check Valve and Reduced Pressure Type backflow assemblies, in an approved configuration may be used as premises-isolation backflow protection. State and/or City required premises-isolation backflow protection is a condition of water service and/or continued service where an existing service requires premises-isolation, such must not be removed or relocated without first contacting the Water Bureau Water Quality Inspection group.  Assemblies approved by the Water Bureau to be installed inside buildings, must be installed on the inside wall at the elevation of service penetration on the centerline of the city water service.  If the service enters the building from below grade or at an elevation less than 1-foot above finished floor (AFF), the assembly is to be raised to 1-foot AFF (measured to bottom of assembly body).  If the service enters at a point greater than 5-feet AFF, the assembly must be dropped down to 5-feet AFF (measured to top of assembly body).  If the service enters the building at an elevation between one and five-feet AFF, the assembly must be installed at service entrance elevation.  Services that enter at elevations excessively (to be determined by the Water Bureau) greater than 5-feet AFF will require a permanently mounted platform be installed as outlined herein.  Premises isolation assemblies approved to be installed inside buildings or structures must be installed at the water supply riser.  The riser must be installed 12” from the building or structure wall to the centerline of pipe on the centerline of the city water service as it runs perpendicular from the right-of-way. Foundations, footings, slabs, and/or walls must be sleeved or core-drilled to accommodate code-compliant riser and service entrance locations.

2.  The installation of a backflow assembly may alter system operating pressure, flow and/or influence other hydraulic functions.  Additionally, thermal expansion may result from the installation of a backflow assembly.  The water user/installer is responsible for ensuring system operating requirements can be met.

3.  Retro-Fit/Replacement backflow assembly installations must meet current State and City installation requirements.

4.  Backflow assemblies must be protected from severe environmental conditions (i.e. insulated enclosure and insulate exposed piping or provide a heat source).

5.  Backflow assemblies must be approved by the Oregon Health Authority (OHA).  Installations must meet minimum application requirements of OAR 333-061-0070 Tables 42 and 43, respectively.  Only assemblies approved by OHA and the Water Bureau may be installed vertically.  In addition to Title 21 & 28 of the City Code, OAR 333-061-0070, Section 14, will apply to all existing premises-isolation backflow assembly installations.  Required permits must be obtained and associated fees be paid prior to installing a premises-isolation backflow assembly.

6.  Assemblies must be readily accessible with adequate room for testing and maintenance:

  • Assemblies 2” and smaller (excludes DCDA’s, see next bullet) must maintain at least 4” clearance on all sides and at both ends respectively.
  • Assemblies larger than 2” (includes 2” DCDA’s) must maintain at least 4” clearance on the backside, 3” at both ends, 12” underneath, 24” in front and 36” vertically.  See required headroom clearances for vault, chamber/enclosure and basement installations under Additional installation requirements for vaults and enclosures.

7.  A minimum of a Double Check Valve Assembly (DCVA) must be installed on water services:

  • If the water meter is 2” or larger.
  • If the service supplies properties where vending cart(s) are permitted. Where Frost-Free Drain-Back Yard Hydrants and/or Sanitary Yard Hydrants are used on the premises RPBA protection must be provided.
  • All services considered non-potable in nature are to be equipped with a minimum of a DCVA as premises-isolation protection.
  • If the Water Bureau determines the backflow potential warrants.

8.  Premises-Isolation assemblies installed at an elevation greater than 5-feet to top of assembly AFF must have a permanently installed scaffold or platform.  Installations must meet Occupational Safety and Health Administration and State of Oregon Occupational Safety and Health codes.

9.  Title 21.24.040 requires access be granted to all premises for inspection of water piping, as described therein.

10. Upon completion of a premises-isolation backflow assembly installation for new construction and/or replacement of an existing assembly, the Portland Water Bureau must be notified. Assemblies must be inspected by a Water Bureau Water Quality Inspector and will require that a Backflow Inspection Fee be paid.

11. Water service will not officially be activated and is subject to termination without notice until all installation related work has been completed.  Work must be completed prior to temporary or final occupancy being granted by the local Building Inspector.

12. Assemblies over 2” in size (includes 2” DCDA/RPDA) must be supported by rigidly mounted metal supports (Standon Pipe Supports or equivalent) underneath the shut-off valves at both ends of the assembly. All above-ground enclosures for assemblies must be provided with concrete floors/pads, which may not be less than 4” in thickness.  If suspended from ceilings, pipe hangers designed to carry the full load of the assembly must be installed.

Additional installation requirements for vaults and enclosures

When a Double Check Valve Assembly (DCVA) or a Double Check Detector Assembly (DCDA) is installed in a vault the following must be provided:

1. Adequate drainage:  Backflow assemblies must not be installed in locations subject to flooding.  Vault/enclosure installations must be provided with adequate drainage and drains may not be connected or discharge to sewers, catch basins, below the flood rim of swales or riverbanks.  A sump pump will be required if vaults/enclosures are unable to be kept free of standing water.  Sump pump discharge piping must meet vault drainage requirements stated herein.

2. Vault lid with frame and hinged cover: (Oldcastle Infrastructure or equivalent) where applicable use Center-Offset frame and cover lids (Oldcastle Infrastructure or equivalent).  These will allow for necessary clearance for ladders in single assembly installations.  For multiple assemblies in the same vault, (Oldcastle Infrastructure or equivalent) centered frame & cover lids may better accommodate installation criteria.  A minimum 30” manhole cover, with a recessed lift handle, may be used in parking lot and driveway installations, only where traffic loading exceeds that of a traffic rated frame and cover (Oldcastle Infrastructure H-20 rating or equivalent).

3. An approved rigidly mounted ladder, with an extension which extends 3’ above the vault lid (Oldcastle Infrastructure Pull-Up Extension, Bilco LU-1 or equivalent) is required if the vault or chamber is 4’ or greater in depth.  The ladder must be mounted vertically in the entryway of the vault or chamber and be securely anchored at top and bottom.  Ladder orientation must not impede clear access to the assembly and/or vault floor.  The top and bottom rungs must be within 12” of the opening and floor, respectively.  All rungs must have at least 7” of toe clearance, with the exception; if the top rung is at the same elevation as the opening the clearance may be no less than 2.5”.  The ladder must not infringe on the installation clearances for the type of assembly required.  For single & multiple assembly installations, refer to item #2 above to ensure proper ladder placement.

4. A moisture-proof light fixture will be required if adequate lighting is not available.

5. At least 6’ of vertical headroom is required for all vault, chamber, enclosure and basement installations.   Full opening double doors (Oldcastle Infrastructure or equivalent) can be used to obtain the 6’ requirement but must encompass the entire lay-length of the assembly and must not encroach on required ladder clearances.  Refer to item #2 above for proper vault lid and frame & cover applications. 

6. Assemblies 2” and smaller that are configured in the “Y” pattern design must be installed on their side with the test cocks facing up.

7. It is recommended when 2” and 1-1/2” Double Check Valve Assemblies (Excludes fire service assemblies, see information under “fire sprinkler services”) are installed below grade the Carson Industries plastic box #1730-18 be used or equivalent.  For 1” and smaller assemblies, Carson Industries box #1419-18 is recommended or equivalent.  All assemblies 2” and smaller (Excludes fire service assemblies, see information under “fire sprinkler services”) must be installed no more than 24” below finished grade.  If installed deeper, clearances must meet those specified on page 1 item 6 (second bullet).

8. In addition to Portland Water Bureau requirements, all vault installations must meet City of Portland Bureau of Development Services standards and will be subject to all applicable permit requirements.

9. All backflow assemblies installed below grade must be provided with test cock plugs.

10. For assemblies larger than 2” (Includes 2” fire service DCDA’s, see section Requirements for backflow assemblies installed on fire sprinkler services), only pre-cast vaults (Oldcastle Infrastructure or equivalent) that accommodate the installation criteria will be accepted.  This applies to all below grade new service and retrofit of existing service installations.

11. Above ground enclosure installations may have clearances less than those mentioned on page 1 item 6, provided they are equipped with removable panels or doors that create clearances equal to or greater than those described herein.  Wood framed enclosure will be approved on a case-by-case basis and approved drawings submitted to the Bureau are required prior to construction.  Such installations must provide protection from freezing.

12. All vaults and enclosures for backflow assemblies must be kept free of any debris, objects that interfere with these installation requirements and those applicable to OAR 333-061-0071.  Vaults and enclosures must not contain loose fill materials of any kind.

Installation requirements for the reduced pressure backflow assembly (RPBA)

1. An approved airgap must be located directly below the relief valve orifice.  The airgap must be at least twice the inside diameter of the supply piping measured vertically above the top of any drain or receiving vessel.  The air-gap must never be less than 1”.  A RPBA must always be installed above finished grade meeting applicable drainage requirements unless an alternate enclosure installation is able to meet all applicable criteria as stated herein.  See item #1 of the first page for more detailed above-finished-floor (AFF) elevation criteria.

2. When the RPBA is installed in an above ground enclosure, the enclosure drain must drain to finished grade and be able to discharge the full rated flow of the relief-valve.  The relief-valve must be located at least 12” above the top of the drain opening.

3. When a RPBA is installed in an enclosure in a berm or hillside, the enclosure must be equipped with a horizontal boresight drain to daylight, which must discharge to finished grade and/or be above the 100-year flood plain, whichever is greater.  The relief-valve must be located at least 12” above the top of the drain opening.  The bottom of the discharge end of the bore-sight drain must be at least 12” above the flood rim of any physical feature such as but not limited to; ponds, fountains, lakes, rivers, swales and/or any other type of receiving vessel.  The bore-sight drain must be screened off at both ends and must not have a lay length of more than 20’.  The bore-sight drain must never be connected to sewers, catch basins, sumps, dry wells or other similar facilities.

4. The proposed installation of a RPBA in an area that may be subject to flooding must be reviewed and approved by the Portland Water Bureau on a case-by-case basis.  Interior and Basement installations must provide drainage for the full rated flow of the relief valve and/or the RPBA supply piping must be equipped with an approved Flood Protection Shut Down Valve.

5. An RPBA must be installed on all water service connections that pose a risk to health.  The Portland Water Bureau will determine the degree of risk.  A RPBA installed in a potable water system must meet applicable Plumbing Code requirements and be compliant with all applicable rules as outlined in Oregon Administrative Rule 333-061-0070, Tables 42 and 43, respectively.

6. A reduced pressure type backflow assembly is required to be installed on all water service connections to premises having private wells, water features, geothermal heating & cooling systems, hydronic heating systems, cooling towers, that front rivers, lakes/ponds or other water sources that can be connected to; are equipped with storage tanks, rainwater-harvesting (excluding those that simply capture rainwater in containers of less than 50 gallons and gravity-feed to landscape), storm-water or groundwater recovery and reuse systems and/or that use or reuse treated wastewater (grey and/or black-water) on site.  A RPBA will be required to be installed on any water service that provides for the use of water as a medium for purposes other than potable drinking water and/or where the water is treated in any way.  Assemblies must be installed on private property at the property line adjacent to the service connection to the premises.

7. A RPBA must be installed on all service connections to industrial premises where complex (degree of complexity to be determined by the Water Bureau) intricate plumbing systems exist.

8. Services supplying premises that are equipped with frost-free drain-back yard hydrants and/or Sanitary Yard Hydrants must be protected with a RPBA.

9. A reduced pressure type assembly must be installed on all water service connections to premises with high-rise buildings (high-rise building: where a building is 75-feet or greater above its lowest finished floor elevation to top of structure).

10. A reduced pressure type backflow assembly will be required on services to premises with piping systems adjacent to waterways that may be subject to immersion due to periods of highwater incidents.  If available, current GIS data will be used to make this determination.

11. A RPBA must be installed on domestic water services to mixed-use and multi-tenant premises.

12. A RPBA must be installed on domestic water services to premises with shell building or structures when occupancy is undetermined at the time of construction and/or renovation.

Requirements for backflow assemblies installed on fire sprinkler services

1. A Double Check Detector Assembly (DCDA) is typically the type of backflow assembly installed on fire sprinkler water services.  See note below.  If the fire sprinkler service is fully metered (a meter approved by the Water Bureau for billing purposes) a Double Check Valve Assembly (DCVA) or Reduced Pressure Backflow Assembly (RPBA) may be installed depending on sprinkler system type.  NOTE: A Reduced Pressure Detector Assembly (RPDA) is required to be installed when; rainwater-harvesting, storm-water or groundwater recovery and reuse systems are installed and/ or that use or reuse treated wastewater (grey and/or black-water) for the purpose of augmenting the fire sprinkler system in any capacity.

2. Backflow assemblies installed on water services for fire use only: Must be installed on private property at the property line, adjacent to the service connection to the premises and be as close to the city water main as possible.  If the available area between a building and the property line is adequate (determined by the Bureau), the vault, chamber or housing for the type of backflow assembly required must be installed outside the confines of the building or structure.  If the available area is not able to accommodate the enclosure required (determined by the Bureau), the assembly must be installed on the inside building wall and conform to the above finished floor (AFF) criteria on page one of this document.  The water supply riser must be installed 12” from the building or structure wall to centerline of pipe on the centerline of the city water service as it runs perpendicular from the right-of-way.  Prior to installing a backflow assembly within a building or structure, accurate drawings must be submitted to the Portland Water Bureau Water Quality Inspection group for approval.  Drawings must show property lines, building setbacks, identify street frontage, water main, service location and proposed backflow assembly type and location.  An inspection fee must be paid to the Water Bureau prior to replacement of an existing assembly or newly installed assembly on a dedicated fire service.  Where existing fire sprinkler system water piping is significantly remodeled (significance determined by the Bureau) or modified, unapproved assemblies and or devices are to be replaced with those currently approved.  The installation must be compliant with this code and/or any applicable OAR Chapter 333 Rules.  See OAR 333-061-0070, Section 14, which specifically addresses existing installations.  Additionally, all piping for fire sprinkler system backflow assembly installations must be compliant with the local Fire code.  Underground piping requires a minimum 3 feet of cover and may also require a permit be taken out from the Fire Marshal’s office.

3. Where anti-freeze compounds, chemicals, gases or any other additives are added to a fire sprinkler system, a Reduced Pressure Detector Assembly (RPDA) will be required.  Where it is possible for a fire sprinkler system to be connected to or be augmented by any auxiliary water source a RPDA will be required.  The RPDA must be installed at the service connection as outlined herein.  All applicable RPBA installation criteria will apply (see Installation requirements for the reduced pressure backflow assembly).  Fire systems that incorporate the use of storage tanks must be equipped with a RPDA and are required to be installed at the service connection to the premises as outlined herein.

4. When a DCDA is installed in a vault the metered by-pass must be plumbed on the side of the assembly opposite of the ladder.  4” clearance is required between the wall and the bypass, 24” clearance in front, 12” underneath, 3” at both ends and 36” vertically.

Bypass meters equipped with touchread register and touch pad or radio signal transmitters

1. All Double Check Detector Assemblies (DCDA’s) and Reduced Pressure Detector Assemblies (RPDA’s) installed on fire services must be equipped with a Water Bureau approved bypass meter and compatible touch-pad.  The touch-pad must be accessible from the right-of-way.

2. Only 5/8”x 3/4” Neptune T-10 meters with PROREAD or AUTOREAD registers are to be used.  Registers must read in cubic-feet.  Touch-pads must be compatible with these meters.  Compatible touch-pads for the above meter are Neptune model #12081-000 (wall mount application), Neptune model 12223-150 (vault door application, requires 1 ¾” hole).

3. All wiring from the touch-pad to the bypass meter must be insulated 1 pair solid 22 AWG copper wires secured so as not to interfere with the operation and maintenance of the backflow assembly. The wiring must not encumber the vault opening or ladder.  Where the touch-pad wire follows the path of other electrical wiring, shielded wire as described above must be used. Splices must be made with 3M Scotchlok moisture resistant connectors, part number UR or UY or equivalent. All splices must be accessible.

4. Touch-pad mounting options:

  • On an outside building wall, at a height between 1’ and 5’ above the floor or finished grade and within 50’ of the backflow assembly. All wires running from the bypass meter to the touch-pad must be in conduit.
  • May be mounted on the vault door.  This orientation should locate the touch-pad near the hinged portion of the door so as not to stress the wire between the touch-pad and meter when the door is fully opened.
  • May be installed in the concrete portion of the vault top, the touch pad must be easily accessible for replacement.
  • If touch-pad wire must be run underground the wire must be routed through PVC conduit from the meter to the touch-pad.
  • Touch-pads not installed in vault doors or on a building face must be installed using the Brooks #37, 12” X 20” box w/T&R lid. 
  • The touch-pads or transmitters must be rigidly mounted and be serviceable.  Mounting hardware must be of a type whereby removal and reinstallation may be accomplished without damaging the unit.