Backflow assembly installation requirements

1. Premises-isolation backflow protection as required by the State of Oregon and City of Portland is a condition of new or continued water service.
2. Premises-isolation assemblies must not be removed, replaced, or relocated without the approval of the Portland Water Bureau Water Quality Inspection group.
    
   • Prior to installing or replacing a premises-isolation backflow prevention assembly, the Portland Water Bureau Water Quality Inspection group must be notified and the required permits must be obtained.
   • When installation of premises-isolation backflow prevention assemblies are required 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 and building setbacks and must identify street frontage, water main, service location, and proposed backflow prevention assembly type and location.
   • Installations must be inspected by a Portland Water Bureau Water Quality Inspector, and a backflow inspection fee must be paid.
3. Retrofit and replacement installations must meet current state and City installation requirements.
4. Backflow prevention assemblies must be those approved by OHA.
5. Plumbing trade permits must be obtained from Portland Permitting & Development.
6. Fire services may require a permit from the City of Portland Fire Marshal’s Office.

The supply side of premises-isolation assemblies must be plumbed with potable water piping and fittings meeting current NSF/ANSI 372 and NSF/ANSI 61 standards.

OHA maintains a list of approved double check– and reduced pressure–type backflow prevention assemblies that may be used for premises-isolation backflow protection.

A minimum of a double check valve assembly (DCVA) for premises isolation must be installed on water services that do not pose a risk to health and meet the following conditions:
 

• Services with a water meter that is 2 inches in diameter or larger
• All services considered non-potable
• Existing services that are using water for the sole purpose of facilitating temporary construction needs
• All premises with more than one domestic water service
• Services with backflow potential that warrants an assembly, as determined by the Portland Water Bureau

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

1. Backflow prevention assemblies must be protected from severe environmental conditions.
2. Only commercially manufactured, prefabricated, insulated outdoor enclosures are approved.
3. All exposed piping inside enclosures must be insulated with commercially manufactured closed-cell pipe insulation, or a heat source must be provided.

Portland City Code Section 21.60.030 requires access be granted to all premises for inspection of water piping and plumbing fixtures.

1. Water service must not be activated and is subject to termination without notice until all backflow prevention assembly installation–related work has been completed.
2. Backflow prevention assembly installations must be inspected and approved by a Portland Water Bureau Water Quality Inspector prior to temporary or final occupancy being granted by a City of Portland Permitting & Development (PP&D) Building Inspector.

No pressure testing of piping is to be performed between a premises-isolation assembly and a Portland Water Bureau valve or meter in the right-of-way.

For assembly installations that incorporate the use of a wye strainer, the strainer drain valve must not be threaded or otherwise allow for hose connections or other plumbed arrangements that create a potential cross connection.

1. Premises-isolation assemblies that directly protect the public water supply must be installed on private property at the property line (service connection/point of delivery) on the centerline of the City water service as it runs perpendicular from the right-of-way.
2. Premises-isolation assemblies must be installed as close to the point of delivery as possible, as determined by the Portland Water Bureau.
3. If the available area between a building and the property line is adequate, the vault or enclosure for the type of backflow prevention assembly required must be installed outside the confines of the building or structure.
4. If the available area cannot accommodate the vault or enclosure required, the assembly must be installed on the water supply riser/supply pipe.
5. If the Water Quality Inspector determines that arbitrary runs of exposed piping have been installed upstream of a premises-isolation assembly, the assembly may be required to be:
    
   • Relocated
   • Sleeved
   • Labeled
   • Sleeved and labeled

Premises-isolation assemblies must be readily accessible, with adequate room for testing and maintenance. See specifications below:
 

1. Assemblies larger than 2 inches in diameter and all detector assemblies must maintain the following minimum clearances:
    
   • 4 inches on the backside and at both ends
   • 12 inches underneath the lowest part of the assembly body or relief valve
   • 24 inches in front and vertically above the assembly body (this clearance may be reduced to accommodate a platform or enclosure if approved by the Portland Water Bureau Water Quality Inspector)
2. Assemblies smaller than 2 inches in diameter must maintain at least 4 inches of clearance on all sides and at both ends.

Premises-isolation assemblies approved to be located inside buildings must be installed on the riser/supply pipe where the water service enters the open space and/or exits a water meter vault.
 

1. The riser/supply pipe must be installed on the centerline of the service, no more than 1 foot from the property’s immediate inside wall. Foundations, footings, slabs, and/or walls must be sleeved or core-drilled to accommodate code-compliant riser/supply pipe entrance locations.
2. Assemblies installed directly on vertical subgrade risers, or off a riser that enters the space at less than one foot and necessitates the addition of a vertical run of pipe to be raised to observe the required 12-inch minimum elevation, must be on the list of OHA-approved assemblies for vertical installation.
3. For horizontal installations, the riser must be equipped with a single 90-degree elbow and the assembly must be no more than the pipe diameter in inches beyond the centerline (or outlet side) of the elbow, with exceptions made only for necessary appurtenances.
4. An alternate assembly location will only be considered for retrofit applications and will not be considered for new construction. Alternate locations must be approved by the Portland Water Bureau and must not conflict with any applicable OHA administrative rule.

Backflow prevention assemblies installed on water services that enter buildings with subgrade floors must enter the building parallel to the centerline of the City water service.

The required piping elevation is determined by the depth of the City water service at the right-of-way, as specified below:
 

1. If a water service enters a building at an elevation greater than 5 feet above finished floor (AFF), a permanent platform must be installed.
    
   • The platform must provide for 6 feet of vertical headroom. Platforms must be engineered to comply with all applicable Oregon Occupational Safety and Health Authority (Oregon OSHA) requirements and must be detailed on all drawings submitted for review and permitting through City of Portland Permitting & Development (PP&D).
2. If a water service enters a building at an elevation between 1 and 5 feet AFF, the assembly must be installed at the elevation the water service enters the building.
3. If a water service enters a building from below grade (slab-on-grade) or at an elevation less than 1 foot AFF, the assembly must be raised to a minimum of 1 foot AFF (measured to the lowest part of the assembly).
    
   • The assembly may be placed at an elevation greater than the minimum to accommodate drainage for a reduced pressure–type assembly relief valve or the installation of a main shutoff valve, a wye strainer, or an emergency shutoff valve.

For approved parallel installations, the premises-isolation assemblies must meet all location and clearance requirements above.

1. Premises-isolation assemblies installed at an elevation greater than 5 feet AFF, as measured to top of assembly body, must have a permanently installed platform.
2. Installations must meet United States OSHA and Oregon OSHA codes. All horizontal and vertical runs of pipe prior to an assembly may be required to be sleeved with schedule-40 PVC pipe.
3. Fire sprinkler system piping will be reviewed on a case-by-case basis regarding sleeving.

Premises-isolation assemblies over 2 inches in diameter and detector assemblies must be supported by rigidly mounted metal supports (Standon pipe supports or equivalent) underneath the shutoff valves at both ends of the assembly.

1. Backflow prevention assemblies must not be installed in locations subject to flooding and may be required to be installed above grade.
2. Vault and enclosure installations must have adequate drainage, and drains may not be connected to sewers of any kind, to catch basins, or below the flood rim of swales or riverbanks.
3. A sump pump will be required if vaults cannot otherwise be kept free of standing water. Sump pump discharge piping must meet vault drainage requirements as stated herein.

1. Vault lids with hinged frame and covers (Oldcastle Infrastructure or equivalent): Where applicable, use center-offset frame and cover lids (Oldcastle Infrastructure or equivalent). These will allow necessary clearance for ladders in single-assembly installations.
2. For multiple assemblies in a common vault, centered frame and cover lids (Oldcastle Infrastructure or equivalent) may better accommodate installation criteria.
3. For parking lot, driveway, loading dock, and heavy commercial traffic applications, a minimum of EJ #8217 36″ X 36″ or #8217 Double 36″ X 74″ frame and covers or equivalent must be used. As determined by the Portland Water Bureau, EJ #8197 36″ X 36″ or #8197 Double 36″ X 74″ frame and covers may be required.
4. Maintenance hole covers are not permitted.

1. An OSHA-approved rigidly mounted ladder with extension (Oldcastle Infrastructure Pull-Up Extension, Bilco LU 1, or equivalent) is required.
2. The ladder must be mounted vertically in the entryway of the vault or chamber and must be securely anchored at top and bottom.
3. Ladder orientation must not impede clear access to the assembly or floor.
4. The ladder must not encroach on the installation clearances for the type of assembly required.

1. At least 6 feet of vertical headroom is required for all vault, chamber, and basement installations.
2. Full opening double doors (Oldcastle Infrastructure 332P-2, EJ #8127 Double, or equivalent) can be used to meet the 6-foot requirement but must encompass the entire lay-length of the assembly and must not encroach on required ladder clearances.
    
   • Refer to Vault lid requirements above for proper vault lid, frame, and cover applications.

1. Premises-isolation assemblies 2 inches in diameter and smaller (excluding detector assemblies; see Dedicated fire service requirements below) must be installed no more than 24 inches below finished grade.
2. Premises-isolation assemblies larger than 2 inches in diameter must be installed in precast vaults (Oldcastle Infrastructure or equivalent). This applies to all below-grade installations for new services and retrofit of existing services.

All backflow prevention assemblies installed below grade must be provided with test port plugs.

1. All aboveground enclosures must be provided with concrete floors/pads, which must be at least 4 inches thick. If suspended from ceilings, pipe hangers designed to carry the full load of the assembly must be installed.
2. Aboveground enclosure installations may have clearances less than those mentioned for vault installations, provided they are equipped with removable panels, doors, and tops that create clearances equal to or greater than those described in Clearances above.
    
   • Only commercially manufactured, prefabricated, insulated outdoor enclosures will be approved.
   • All exposed piping inside enclosures must be insulated with commercially manufactured closed-cell pipe insulation, or a heat source must be provided.

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

The Portland Water Bureau will review all water services. Those determined to pose a risk to health will require installation of a reduced pressure–type assembly for premises isolation.

The following is a non-exhaustive list of the types of water service connections that require installation of a reduced pressure–type assembly:
 

• On domestic water services to mixed-use and multi-tenant premises
• On domestic water services to premises where shell buildings are constructed or renovated when occupancy is undetermined at the time of construction and/or renovation
• On domestic water services to vending/food cart lots
• Where chemicals are added or the water is treated in any way
• Premises with private wells, water features (swimming pools), geothermal heating and cooling systems, hydronic heating systems, or cooling towers
• Premises that have access to rivers, lakes, ponds, or other water sources that can be connected to
• Premises equipped with storage tanks or rainwater-harvesting systems (excluding those that simply capture rainwater in containers of less than 50 gallons and gravity-feed to landscape)
• Premises with stormwater or groundwater recovery systems or that use treated wastewater (greywater or blackwater) on-site
• On all service connections to industrial premises where complex, intricate plumbing systems exist
• On services supplying premises that are equipped with frost-free drain yard hydrants or sanitary yard hydrants
• On all water service connections to premises with high-rise buildings, defined as buildings measuring 75 feet or more from above the lowest finished-floor (slab) elevation to the top of the structure
• On services to premises with piping systems adjacent to waterways that may be subject to immersion due to periods of high water

1. The proposed installation of a reduced pressure–type assembly in an area that may be subject to flooding must be reviewed and approved by the Portland Water Bureau Water Quality Inspection group prior to installation.
2. Interior and basement installations must provide drainage for the full rated flow of the relief valve, or the supply piping must be equipped with an approved flood protection shutdown valve.

1. An approved airgap must be located directly below the relief valve orifice.
2. The airgap must be at least twice the inside diameter of the relief valve, measured vertically above the top of any drain or receiving vessel. The air gap must never be less than 1 inch.
3. Reduced pressure–type assemblies must always be installed 12 inches above finished grade or the 100-year flood level, whichever is higher.

1. When a reduced pressure–type assembly is installed in an aboveground enclosure, the enclosure must drain to finished grade and be able to discharge the full rated flow of the relief valve.
2. The relief valve must be located 12 inches above finished slab elevation.

When a reduced pressure–type assembly is installed in a vault in a berm or hillside:
 

1. A horizontal bore-sighted drain to daylight must be provided with a clear, unobstructed path, allowing for bore-sight inspection.
2. The bore-sighted drain must be screened off at both ends and must not have a lay length of greater than 20 feet.
3. The bottom of the discharge end of the bore-sighted drain must be at least 12 inches above the flood rim of any physical feature such as, but not limited to, ponds, fountains, lakes, rivers, swales, or any other type of receiving body.
4. The drain must discharge to finished grade or be above the 100-year flood level, whichever is higher.
5. The bore-sighted drain must never be connected to a sewer of any kind, catch basins, sumps, or dry wells.
6. The relief valve must be located 12 inches above the top of the vault drain opening.

A detector assembly is the type of backflow prevention assembly required on fire water services that are not fully metered.
 

1. A double check detector assembly (DCDA) is required on fire services that do not pose a risk to health.
2. A reduced pressure detector assembly (RPDA) is required when the following health risk criteria exist:
    
   • Premises where the fire sprinkler system is augmented by antifreeze compounds, chemicals, gases, or any other additives
   • Premises with high-rise buildings, defined as buildings measuring 75 feet or more from above the lowest finished-floor (slab) elevation to the top of the structure
   • Premises with fire services that supply marinas, moorages, docks or piers
   • Premises with an auxiliary water source, storage tank, rainwater-harvesting system, or stormwater or groundwater recovery and reuse system; or premises that use or reuse treated wastewater (greywater or blackwater)
3. If the fire service is fully metered using a Portland Water Bureau–approved meter, the hazards will be reviewed to determine whether a double check valve assembly (DCVA) or reduced pressure backflow assembly (RPBA) will be required.

When existing fire sprinkler system water piping is significantly remodeled or modified by more than 2 sprinkler heads, unapproved assemblies must be replaced with currently approved assemblies.

All required DCDAs and RPDAs must be equipped with a Portland Water Bureau–approved bypass meter and compatible touchpad. The touchpad must be accessible from the right-of-way.
 

1. Only 5/8″ x 3/4″ Neptune T-10 positive displacement meters with high-resolution registers may be used. Registers must read in cubic feet. Touchpads must be compatible with these meters. Compatible touchpads are Neptune model #12081-000 for wall mount applications and Neptune model #12223-150 for vault door applications that require a 1¾″ hole.
2. Wiring from the touchpad to the bypass meter must be insulated, 1 pair, 22 AWG solid copper.
3. Wiring must not encumber the vault opening or ladder or interfere with the operation, maintenance, or testing of the backflow prevention assembly.
4. Where the touchpad wire follows the path of other electrical wiring, all wiring must be shielded to protect from electrical interference.
5. Splices must be accessible and made with 3M Scotchlok moisture-resistant connectors, type UR, UY, or equivalent.
6. If touchpad wire must be run underground, the wire must be routed through PVC conduit from the meter to the touchpad.
7. Touchpads must be rigidly mounted and serviceable. Mounting hardware must be of a type that allows for removal and reinstallation without damaging the unit.
8. Touchpad mounting must meet the following location requirements:
    
   • May be mounted on a fence via a junction box or an exterior building wall no greater than 5 feet above the floor or finished grade. All wires running from the bypass meter to the touchpad must be in conduit.
   • May be mounted on the vault door. This orientation should locate the touchpad near the hinged portion of the door so as not to stress the wire between the touchpad and meter when the door is fully opened.
   • May be installed in the concrete portion of the vault top. The touchpad must be easily accessible for replacement.
   • Touchpads may be installed using the Brooks #37 12″ X 20″ box with a touch-and-read lid or equivalent.