What Is a Combination Drain and Vent System?

Combination Waste and Vent System. A specially designed system of waste piping embodying the horizontal wet venting of one or more sinks or floor drains by means of a common waste and vent pipe adequately sized to provide free movement of air above the flow line of the drain.

What types of fixtures can be served by a combination waste and vent system?

A combination waste and vent system shall only serve floor drains, sinks, lavatories and drinking fountains. A combination waste and vent system shall be considered to be the vent for those fixtures.

What is the difference between a drain pipe and a vent pipe?

Drainage pipes carry waste out of your home to either the city sewer or a septic tank. Vent pipes supply fresh air to each plumbing fixture in the house, which helps the system move water through the drainage pipes each time a toilet is flushed or a sink is drained.