All plumbing fixture drain lines need to be vented. The air vent allows for air in to the drain system so water will flow properly. Think of how a soda bottle goes gulb when you poor it as the air goes into the bottle to replace the liquid coming out. Without the introduction of air, a vacuum will form and the liquid will stop flowing.
See our article on Properly Venting a Plumbing Fixture
A drain system therefore must also be vented. Installing a vent line in some areas, such as a kitchen island or a basement can be an issue particularly if the walls are all closed.
Using an automatic air vent in a cabinet or exposed if you don’t mind the look can solve this issue.
These devices have been used for decades and are approved by must building codes. Be sure to check with your local code official before installing one.
Check out the video below to see how to install an automatic air vent.
