Question 1

What is backflow in a plumbing system?

Accepted Answer

Backflow is the undesirable reversal of flow of water or other substances from any source back into the potable water distribution system.

Question 2

What is the difference between backsiphonage and backpressure?

Accepted Answer

Backsiphonage is caused by negative pressure (partial vacuum) in the supply line, while backpressure occurs when downstream pressure exceeds the supply pressure.

Question 3

What is a cross-connection in plumbing?

Accepted Answer

A cross-connection is any physical link between a potable water supply and a source of contamination or pollution that could allow backflow to occur.

Question 4

What is an air gap, and what degree of hazard does it protect against?

Accepted Answer

An air gap is the unobstructed vertical distance between the lowest opening of a water supply outlet and the flood level rim of a fixture. It is the highest level of backflow protection and protects against both high and low hazard conditions.

Question 5

What minimum air gap is required between a potable water outlet and the flood level rim of a fixture for a 1-inch pipe?

Accepted Answer

A minimum air gap of 2 inches (twice the diameter of the supply pipe, but not less than 1 inch) is required for a 1-inch pipe under most codes.

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