After you have installed your new triple sink, you may want to consider how to plumb it. Consult with your local inspector or plumbing contractor to determine what local codes require. Triple sinks do provide a challenge, but with the right parts and a bit of plumbing experience, the job can be done. Triple-sink plumbing kits generally are available at hardware stores, though in some cases you may have to mix and match pieces to get a proper install.
Turn off your supply valves underneath the sink. Place towels and buckets under the sink so you can catch any water once you begin to disassemble your old sink plumbing. Remove all the under-sink plumbing, using your pipe wrench. Remove all the pieces completely back to the wall outlet. You do not need to shut off your water supply.
Separate all the pieces that come in your triple-sink kit. The kit consists of two long elbow sections that will connect the left and right bowls, a center tee section that will connect the center drain, and two drain tailpiece sections.
Dry-fit all the horizontal sections of your PVC kit underneath the sink. This will include the two long elbow connections and the center tee section. Use a permanent marker to mark where they will need to be cut.
Cut the PVC pieces to fit with your hacksaw. Check to see where your wall drain is. Center-set drains will install directly to your p-trap kit with no additional pieces usually needed. Offset drains may require you to install your p-trap kit and then use a flexible drain extension to curve the drain around so it lines up with the wall outlet.
Install your PVC p-trap kit onto the bottom of the center-set tail piece. Line it up with the wall. Use the flexible tailpiece extension if needed as described in Step 5.
Install tailpiece extensions to the bottom of your sink drains if needed. Tighten down all connections and check for leaks. See the Tips section for connector instructions.