of the island and vent off the top of the drain. Attach toward the trap and reverse 180 degrees so any water in the vent flows down the drain. Slope drain down, slope vent up, and attach to existing vent from previous existing fixture that is now abandoned. Patch previously existing drain to become vent. In Canada, the national plumbing code requires that the minimum trap arm be at least 2 times the pipe diameter, (e.g., 1.25 inch pipe needs a 2.5-inch trap arm, 1.5 pipe needs a 3-inch trap arm, etc.) and that the vent pipe be one size larger than the drain that it serves, also a cleanout is required on both the vent and the drain. The reason for this is in the event of a plugged sink, the waste water will back up and go down the vent, possibly plugging the vent (as it is under the countertop), and a clean-out would permit the cleaning of the pipes. Fittings All DWV systems require various sized fittings and pipes which are measured by their internal diameter of both the pipes and the fittings which, and in most cases are schedule 40 PVC wye's, tee's, elbows ranging from 90 degrees to 22.5 degrees for both inside diameter fitment (street) as well as outer diameter fitment (hub), repair and slip couplings, reducer couplings, and pipe which is typically ten feet in length. All DWV system fittings sizes are based on the inside diameter of the pipe that goes into the fittings. These are known as hub fittings. Sizes for hub fittings such as wye's and tee's and crosses are based on the inside diameter of the pipe that goes into the hub of the fittings. Items such as washer boxes and Studor vents are also measured by the internal diameter of the fittings. Schedule 40 PVC DWV systems are ideal for several different reasons and are replacing cast iron DWV systems in many municipalities in the US because of issues that cast iron systems present. Parts are no longer available for cast iron plumbing repairs or for installation due to being phased out for lighter and more sanitary materials. Since the advent of PVC and solvent weld adhesives, which is what holds the fittings together by melting the material into itself, along with the proper placement of support throughout the dwv system using strapping and jhooks as well as