When installing sinks in bathrooms and kitchens, as well as when you install a dishwasher, in some circumstances you must run drainpipes through base cabinets. Understanding when you need to do so helps you plan ahead for the installation process. While cutting the holes for the pipes, you should remove drawers or objects in the cabinets to give yourself enough clearance to work.
A dishwasher may not sit right next to the opening under your sink, requiring you to run drainpipe and other hardware through the base cabinets in your kitchen. The dishwasher’s drain line connects to the sink’s drainpipes, either at the garbage disposal or on the drainpipe before the trap piece. The dishwasher’s water line may also connect to a water supply valve that sits near or under the sink, requiring you to run the water supply line through the base cabinets so you can connect it to the dishwasher. The dishwasher’s electrical line may not feed through the wall in the dishwasher’s cutout, requiring you to run the electrical line through the base cabinets in a direction other than to the sink.
When your bathroom or kitchen has a dual sink setup, you must connect the sink’s drainpipes together. The sinks must share the same stub-out, which is the waste pipe that protrudes from the wall. In some setups, the stub-out sits between the two sinks, while in others the stub-out sits closer to one sink than the other. If there are any cabinets between the sinks, you must run drainpipes through the cabinets to properly drain both sinks.
Double Bowl Sinks
Even though double bowl kitchen sinks have separate drains in the sink’s double bowls, the sink’s drainpipes likely run only through the base cabinet below the sink. Since the area under the sink typically is open, you do not need to make any holes in the cabinets to install the drainpipes for the dual drains. As with any other sink setup, if the stub-out pipe sits outside the opening under the sink, you must run the drainpipe through the cabinets to a point where it can connect with the stub-out.
When you run drainpipes, a dishwasher’s water supply pipe or electrical wiring through base cabinets, you must cut holes in the cabinet’s partitions. While you can cut such holes with a handsaw, using instead a hole saw attachment on a power drill provides a cleaner and quicker method. Some hole saw attachments are adjustable, allowing you to cut a number of different hole sizes, while others cut only one size of hole. Remember that when you are cutting holes for drainpipes or anything else in a cabinets’ partitions, you must make the hole slightly bigger than the pipe so the pipe or other hardware can fit through the cutout.