ASSE 6030 key terms

Any actual or potential physical link between a potable water supply and a source of contamination or pollution. Such a link allows unwanted material to enter the drinking water system if pressure conditions reverse.

The unwanted reverse flow of water, liquids, gases, or other substances into the potable water distribution system. It occurs whenever downstream pressure exceeds supply pressure or a negative pressure develops.

Backflow caused by a negative or sub-atmospheric pressure in the supply piping, which draws nonpotable material into the system. Common causes include main breaks, heavy demand, and nearby firefighting.

Backflow resulting from downstream pressure that is higher than the supply pressure in the potable system. Pumps, boilers, elevated tanks, and thermal expansion commonly create this condition.

A condition that degrades water quality but does not create an actual health hazard. Examples include taste, odor, or color changes that make water unappealing without causing illness.

Any impairment of water quality that creates an actual health hazard to consumers. It implies the presence of disease-causing organisms, toxic chemicals, or other harmful substances in the supply.

A physical separation between the free-flowing discharge end of a supply pipe and the flood-level rim of a receiving vessel. It is the highest level of backflow protection available.

A testable backflow prevention assembly containing two independently acting check valves and a hydraulically operated differential relief valve. It protects against both backsiphonage and backpressure at high hazard levels.

A testable assembly with two independently acting check valves in series. It protects against backpressure and backsiphonage where the hazard is pollution rather than contamination.

A testable assembly with one or two check valves plus an air inlet that opens at low supply pressure. It protects against backsiphonage only and must be installed above the highest downstream outlet.

A vacuum breaker designed so the air inlet stays closed under normal supply pressure and opens only during backsiphonage. It may be installed in pits where ordinary vacuum breakers would spill water.

A non-testable device with an air inlet that opens when flow stops or pressure drops, admitting air to break a siphon. It must be installed at least six inches above the highest downstream outlet.

A valve that permits flow in only one direction and closes automatically when flow reverses. In backflow assemblies, check valves are spring-loaded or resilient-seated to hold tight against reverse pressure.

The differential pressure relief component of a reduced pressure principle assembly. It discharges water to atmosphere when the pressure differential between the zones falls below the design threshold.

A port on a vacuum breaker that opens to atmosphere to admit air and break a vacuum. Its proper opening and closing are checked during field testing of the device.

The process of rating a cross-connection by the degree of risk it poses, usually as high (contamination) or low (pollution). The rating determines which type of backflow protection is required.

A measure of the seriousness of the potential harm from a cross-connection, considering the toxicity, pathogen content, and concentration of the contaminant. It drives selection of the appropriate protective device.

The edge of a receiving vessel or fixture where water would overflow onto the floor. It is the reference point for setting the minimum air gap or vacuum breaker elevation.

The marked elevation on a backflow device that establishes the minimum height above a flood-level rim or outlet. Installation below this mark can render the device ineffective and is a common inspection failure.

The increase in water volume as it is heated in a closed system, which raises pressure and can cause backpressure or relief valve discharge. Expansion tanks or thermal relief devices are common remedies.

A piping arrangement with no open outlet that allows water to expand freely, such as a system with a check valve or backflow preventer at the service. It requires thermal expansion control.

A pressure surge caused by the sudden stop of flowing water, producing a shock wave in the piping. It can damage backflow assemblies and cause nuisance relief valve discharges.

The difference in pressure between two points in a system, such as across a check valve or between the zones of a reduced pressure assembly. Field tests measure it to confirm proper operation.

A set of calibrated gauges, hoses, and fittings used to verify the performance of a backflow assembly. It typically includes high- and low-pressure gauges and a differential pressure gauge.

A small valved port on a backflow assembly used to attach test equipment and observe pressure at specific points. Opening the wrong test cock during testing can cause water damage or injury.

A valve used to stop flow to a backflow assembly for testing or repair. Both upstream and downstream shutoffs must hold tight for a valid field test.

Backflow protection installed at the service connection or property line to isolate the entire premises from the public main. It is the water purveyor's primary defense against customer-side hazards.

Backflow protection installed at each individual point of use or fixture within a building. It supplements containment by protecting occupants and the building's internal piping from localized hazards.

An organized effort by a water purveyor to identify hazards, require appropriate backflow protection, test assemblies, and maintain records. It typically includes surveys, permits, and enforcement procedures.

Formal credentialing that verifies a person has the training and skill to test backflow assemblies. Many jurisdictions require certification and periodic recertification before accepting test reports.

The systematic retention and tracking of test reports, permits, survey results, and repair records for backflow assemblies. Accurate records support enforcement, audits, and compliance reporting.

A device that admits air into piping when pressure drops, preventing a siphon from forming. Types include atmospheric, pressure, and spill-resistant models, each with specific installation limits.

A general term for any device or assembly installed to stop reverse flow, including air gaps, vacuum breakers, double check assemblies, and reduced pressure assemblies. Selection depends on hazard level.

A synonym for containment protection, referring to protection at the point where a customer's piping connects to the public water main. It shields the distribution system from on-site hazards.

Unwanted water released from a relief valve or air inlet, often from thermal expansion, pressure fluctuations, or debris. It signals a problem and can create slip hazards or water damage.

Measures taken to keep backflow assemblies and piping from freezing, such as insulation, heat tape, or draining. Frozen assemblies can crack and fail, causing contamination and flooding.

The required height of a backflow device above the surrounding grade or flood level. Correct elevation ensures drainage, prevents submersion, and keeps the air inlet or relief port functional.

Adequate floor drains or discharge paths that carry away relief valve discharge and test water. Poor drainage can submerge assemblies, cause flooding, and create health or safety hazards.