If you are replacing your single-bowl kitchen sink with a double-bowl sink and you have a dishwasher, you will need to know how to connect the dishwasher drain line to the new sink drain pipes. Common mistaken assumptions about drain pipes include that they should only be installed by a plumber and that it takes special tools to accomplish. Drain kits are available in hardware stores and are clearly labelled for kitchen or bathroom sinks. In addition, kits are available for the kitchen sink to which a dishwasher drain hose can be connected.
Remove all items from under the kitchen sink. Be sure to place any chemicals out of reach of children during the installation process.
Locate the drain pipe closest to the dishwasher. Place a bowl under the P-trap to catch water when removing the drain pipe.
Turn the nuts on both ends of the P-trap in a counter clockwise direction. If they are difficult to loosen, place the hand towel on the nut and try again. Pull the pipe away from the two pipes to which the P-trap is connected. Allow the water to spill into the bowl.
Remove the pipe that is attached directly to the sink by removing the nut at the top of the pipe. Install the dishwasher drain pipe to the bottom of the sink with the nut provided.
Install the P-trap removed in Step 3. Be certain the nuts are tightly secured to prevent leaks. Install the dishwasher drain hose to the connection provided on the dishwasher drain pipe according to the manufacturer's suggestion.
Some food disposers have connections for a dishwasher drain line with a plug in it to prevent leaks if it is not in use. Remove the plug before connecting the dishwasher drain hose to the food disposer. For installation in a mobile home, see "Kitchen Sink Drain Kit" in the resource section of this article.
Do not use a pipe wrench on the kitchen sink drain pipes, to prevent possible damage. Do not leave cleaning supplies within reach of children.