Backflow Words & Terms

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 Backflow
 Cross-Connection Backpressure Back-Siphonage
 Potable Water  Pollution Contamination  Water Purveyor
 Theft Deterrence  RPP (or RP) DC PVB
 SVB RPDA DCDA 

Backflow

The undesirable reverse flow of water and/or other substances into the distribution pipes of the potable supply of water from any source or sources (example: from the end-user's system into the water supplier's system).

Cross Connection

The term "Cross-Connection" refers to any unprotected actual or potential connection between the potable (clean, drinkable) water system and any other source through which any substance other than potable water may be introduced.  Examples may include: A garden hose connected to an unprotected hose bibb; Jumper connections; Removable sections of piping; Swivel or change-over devices; By-pass arrangements; Any temporary or permanent devices through which backflow can or may occur.

The Cross-Connection Control Program of each Water Purveyor seeks to eliminate or protect all cross-connections in the public water system and to help customers comply with backflow prevention practices and regulations.

Backpressure

A form of backflow caused by any elevation of pressure in the end user's plumbing system, downstream of the supply connection (by pump, elevation of piping, steam pressure, air pressure, etc.).  This would cause or tend to cause a reversal of the normal direction of flow, back toward the supply system, potentially exposing the public water supply to pollution and/or contamination.

Backsiphonage

A form of backflow due to a reduction in supply system pressure, which causes a sub-atmospheric pressure to exist in the public water system. The area of sub-atmospheric pressure draws water from surrounding areas which are higher pressure, potentially exposing the public water supply to pollution and/or contamination.

Potable Water

Water from any source which has been investigated by the health agency having jurisdiction, and which has been approved for human consumption.

Pollution

An impairment of the quality of the water to a degree which does not create a hazard to the public health but which does adversely and unreasonably affect the aesthetic qualities of such waters for domestic use.

Contamination

A hazardous impairment of the quality of the water to a degree which creates an actual danger to the public health through poisoning, the spread of disease, etc.

Water Purveyor

(or Water Supplier) The public or private owner or operator of the potable water system supplying an approved water supply to the public.  Typically referred to as the Water District.  Water Purveyors in San Diego County include: Vallecitos, Sweetwater, Santa Fe, San Diego, Poway, Otay, Olivenhain, Oceanside, Escondido, and Carlsbad, among many others.  Pacific Backflow tests backflow prevention devices in the Water Districts listed here: San Diego County Water Districts.

Theft Deterrence

Backflow prevention assemblies may be locked in various ways in order to deter attempts to steal them.  Some popular methods of theft deterrence are cages, cable locks, valve guards and enclosures.  Pacific Backflow Company can provide standard or custom solutions for your backflow security concerns.  Please note, the installation of theft deterrence is not a guaranty against a backflow preventer theft, but reduces the chance of this potential loss occurring.

Common Backflow Prevention Assembly Types

RPP: (Also called simply "RP") Reduced Pressure Principal Backflow Prevention Assembly.  An approved assembly is composed of two independently acting check valves, together with a relief valve designed to open when the pressure between the check valves gets close to 2 psi below the supply pressure. The assembly must include tightly closing, approved shutoff valves at each end of the assembly, and properly located test cocks to facilitate testing.  This type of backflow preventer is approved for health hazard protection (i.e. contamination) and for non-health hazard protection (i.e. pollution) in both backpressure and backsiphonage situations.

DC: Double-Check Valve Backflow Prevention Assembly.  An approved assembly is composed of two independently acting, check valves, tightly closing shutoff valves attached at each end of the assembly and properly located test cocks.  While this type of backflow preventer is only approved for non-health hazard protection (i.e. pollution), it is approved for both backpressure and backsiphonage situations.

PVB: Pressure Vacuum Breaker Backsiphonage Prevention Assembly.  An approved assembly contains an internally loaded check valve and an independently operated, loaded air inlet valve located on the discharge side of the check valve.  It must include tightly closing shutoff valves attached at each end of the assembly, and properly located test cocks.  This type of assembly is approved for both contamination hazards and pollution hazards, but only in backsiphonage situations. It is not to be used where backpressure may occur.

SVB: Spill-Resistant Pressure Vacuum Breaker Backsiphonage Prevention Assembly.  An approved assembly contains an internally loaded check valve and an independently operated, loaded air inlet valve located on the discharge side of the check valve.  It must include tightly closing shutoff valves attached at each end of the assembly, and a properly located test cock and bleed/vent port.  This type of assembly is approved for both contamination hazards and pollution hazards, but only in backsiphonage situations. It is not to be used where backpressure may occur. They are especially helpful in indoor locations where water discharge is undesirable.

RPDA: Reduced Pressure Detector Assembly.  An approved assembly is specifically designed and composed of a line-size approved reduced pressure principle backflow prevention assembly with a bypass constructed between the shutoff valves.  The bypass shall contain a specific water meter and an approved rduced pressure principle backflow prevention assembly.  The water meter shall accurately record usage of only very low rates of flow (up to 3 gallons per minute) and shall register all flow.  RPDAs are typically used in fire sprinkler system applications and can be used against health hazards and non-health hazards.

DCDA: Double-Check Detector Assembly.  An approved assembly is specifically designed and composed of a line-size approved double check valve assembly with a bypass constructed between the shutoff valves.  The bypass shall contain a specific water meter and an approved double check valve assembly.  The water meter shall accurately record usage of only very low rates of flow (up to 3 gallons per minute) and shall register all flow.  DCDAs are only to be used to protect against non-health hazards and are typically used in fire sprinkler system applications.