Abstract: A vented tailpiece that may be used in existing sink installations is connected to a sink drain and a drainline trap as part of the sink drain line. A vent in the tailpiece releases air upstream of the drainline trap as the air is displaced by liquid flowing through the drain line. A retainer connected to the vent catches liquid escaping through the vent. The retainer may be fitted with an extension if necessary. An overflow valve, which is preferably a float valve, may be attached to the retainer and configured to prevent liquid from spilling out of the retainer if a problem in the drain line causes liquid to back up into the retainer.