Double bowl kitchen sink drains combine water from two basins and deliver it to a building's main drain system. The plumbing pipes in a kitchen sink must have the capability to handle a dishwasher's water flow and a garbage disposal's waste. The plumbing trap, found plumbed into the kitchen sink drain, holds water. The water in the trap stops sewer gas and odours from leaving the building's drain system and entering the kitchen through the drain pipes. Most new kitchen sink drains use PVC or ABS plastic, rather than leak-prone chrome-plated brass, pipes and fittings. (see reference 1)
Roll a handful of plumber's putty into a 1/2-inch thick roll with your hands. Press the plumber's putty roll along the underside of a sink basket's flange next to the threads. A basket's flange, the flat-metal ring surrounding the basket's mouth, rests on the basin's surface around the drain hole, while the remaining part of the basket resides below the basin's surface, inside the drain hole. The flange keeps the basket from falling through the drain hole. Completely surround the flange with the plumber's putty. Break off the extra putty and cover the second sink basket.
Place the baskets in the sink's drain holes. The threads must penetrate the basin, leaving the finished side of the flange exposed.
Slide a rubber gasket and fibre washer over each basket's threads. Slide the rubber gasket on first, then follow it with the washer.
Screw each basket's locking nut on from under the sink. Turn the locking nut with a set of locking pliers while holding the basket still with a set of needle nose pliers, shoved into the drain hole's opening.
Slide a slip nut onto the tail pieces. The tail piece, a 4 inch long and 1-1/2-inch thick pipe, has a flange on one end and comes as a kit with a gasket and metal nut. The gasket slides in the flanged end of the pipe and the nut slides over the pipe and flange.
Cover the basket's tailpiece connection threads, found at the bottom of each basket, with pipe thread compound. Use the compound container's brush, located on the cap, to fill the grooves.
Connect the tail pieces to the basket's threads. Tighten the tail piece's slip nuts with locking pliers.
Slide a slip nut and gasket from the primary side of a sanitary tee onto the primary basin's tail piece. When using a slip nut, use the gasket with the angled edge for pipe connections and the square back washer for flanged connections. The angled edge fits into the seam between the female fitting and the pipe. A slip nut's flat surface pushes the gasket into the seam.
Connect the primary female end of a sanitary tee to the tail piece of the primary basin, turning the tee's secondary drain port towards the other tail pipe, with the gasket and slip nut on the tail piece. The secondary basin taps into the secondary drain port, the drain port located on the side of the tee.
Measure the distance from the bottom edge of the secondary tail piece nearest the primary tail pipe to the inside edge of the secondary female fitting on the sanitary tee with a tape measure. When measuring female fittings, place the end of the tape measure to the rear of the inside of the female fitting's sleeve—the wide part that the male end of the connecting piece slides into—and stretch the tape measure to the next measurement point—in this case the closest edge of the secondary tail pipe. Transfer this measurement to a J-bend pipe using a pencil to make a mark. The closest edge of the tail pipe measurement will correspond to the throat on the J-bend pipe and cross the long, straight section of pipe.
Cut the J-bend pipe at the pencil mark with a hacksaw. Use a razor knife to remove any burs.
Slide the gasket then the slip nut from the J-bend pipe kit down the J-bend pipe from the cut end. Slide the slip nut then the gasket from the secondary side of the tee onto the cut end of the J-bend pipe.
Push the cut end of the J-bend pipe into the secondary side of the tee. Connect and hand tighten the flange end of the J-bend pipe to the secondary basin's tail piece with the J-bend's gasket and slip nut. Tighten the tee's gasket and slip nut to the tee.
Connect the female end of an extension pipe to the male end of the tee using the expansion pipe's gasket and slip nut.
Wipe all debris from the kitchen sink's drain connection pipe with a rag. The drain connection pipe, found stubbed out of the wall or floor, connects the kitchen sink's drain to the building's main drain.
Clean the female connections of a coupling and the connection pipe with PVC primer, using the brush located on the primer's cap. If the connection pipe uses 2-inch pipe then use a 2-inch to 1 1/2-inch reducing coupling. If the connection pipe uses 1 1/2-inch pipe then use a straight 1-1/2 inch coupling.
Spread PVC glue, using the brush on the lid, over the connection pipe and one of the coupling's female ends. Push the two glued surfaces together. Hold the fitting in place for 60 seconds.
Clean and glue a 1 1/2-inch trap adaptor to the connection pipe coupling. A trap adaptor looks like male fittings with a smaller than normal opening on the threaded side. A slip nut and washer comes with a trap adaptor kit.
Hold the trap against the tee's extension pipe. If the connection pipe comes out of the floor, connect an S-trap to the tee's extension and measure the length between the trap adaptor and the female end of the S-trap. Add 1 inch to that measurement. If the connection pipe comes out of the wall, then hold a P-trap against the tee's extension at approximately the same height as the trap adaptor. Measure the length needed for the extension between the trap and the trap adaptor with a tape measure.
Cut the extension pipe with a hacksaw at the measurement mark. Measure from the flanged end, cutting off the straight pipe.
Connect the flanged end of the extension pipe to the trap adaptor with the trap adaptor's gasket and slip nut. Hand tighten the nut.
Place the slip nuts and gaskets from the trap on the extension pipes. Slip the female ends of the trap onto the extension pipes. Hand tighten the slip nuts on the trap and the tee's extension nut.
Check for water leaks. Tighten the slip nuts as needed. Stubborn leaks may require a gasket change.
Wrap slip nuts with a rag while turning them for better grip.