How you connect a garbage disposal to the drain will depend on what setup you have. Do you have a single sink? Or do you have a double sink? A single sink will be the easiest one to hook up. Where a double will require some planning. Let’s look at each one independently of each other.
Tools & Parts List:
- Channellocks
- 1-1/4 or 1-1/2 P-Trap Kit (Both Sink Types)
- 1-1/4 or 1-1/2 Center Drain Kit (Double Sink)
- Threaded Sink Tail Adapter (Double Sink)
- Tail Piece (Double Sink)
- Slip Joint Extension (Single Sink)
- Female Trap Adapter (See Notes)
- Garbage Disposal How To Video
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First let’s look at connecting a garbage disposal to a single drain sink. Your main drain should be 2″ pipe through the back of the cabinet into the wall and some can be 1″ 1/2 as well. If it is 1″ 1/2 then your drain system is most likely 1″ 1/4. If you’re main pipe is 2″ then it is likely that you have 1″ 1/2.
Once you determine the size you can now plan the route of your drain and make a list of parts that you will need.
NOTE: Insinkerators have a 1-1/2 inch discharge tube in box.
Single Sink Garbage Disposal Drain Connections
Now with the single sink drain you need to have a p-trap kit that will connect to the discharge tube on the garbage disposal. You start with the p-trap and connect it to the discharge tube. Then connect the reversible J-bend to the p-trap.
You will be able to adjust the height of the p-trap kit on the discharge tube so that the exit side of the J-bend will connect to the main drain going through the wall. Keep in mind that no two plumbing jobs are the same and what works for someone else might not work in your situation so you need to be able to adjust on the fly.
Additional parts may be needed to make all your connections work. For example you may already have the exit connector on the 2 inch pipe that the reversible J-bend will slide in. If you don’t you will need it. Another thing you may need is an additional threaded slip joint extender in case your drain is lower than the p-trap will connect straight into.
Double Sink Garbage Disposal Drain Connections
Unlike the single sink drain connections the double sink connects can be more of a challenge. Let’s start by discarding the discharge tube of the garbage disposal as we won’t be using it for this type of connection. You will need a 7 inch drain tail piece that will be bolted to the disposal using the flange and bolts that you would have used for the discharge tube.
In addition to the drain tail piece you’re going to need a center outlet continuous waste drain kit, a sink tail piece, a p-trap kit and an elbow coupling. The reason you have to have these parts is the garbage disposal drain is lower than the sink to sink connections and will need to be modified to the height of the garbage disposal.
Depending on which side of the sink you put your disposal on you need to thread the sink tail piece onto the drain basket. Next you will need to cut the excess of the sink tail piece to be inline with the disposal drain. If you haven’t already done so attach the p-trap and reversible J-bend to the main drain exit into the wall.
Now attach the elbow coupling to the sink tail piece and insert the center T into the top side of the p-trap. You can now begin to make the connection from the disposal to the center T. You may need to cut some off the tail piece attached to the disposal to make the connection. Next take one of the long J-bends that came in the continuous waste drain kit and cut the bend off just where the pipe goes straight.
Now you can put one end of the pipe in the elbow coupling and size up to the center T and cut off the excess and make the connection. Now you should have a fully functioning drain system attached to your garbage disposal.
NOTE: There are debates as to which side the garbage disposal goes on. If both of your sinks are the same size then that debate is over and it won’t matter which side it will go on. Now if you have one deeper than the other then put the disposal on the shallow sink.
This is how you connect a garbage disposal to your drain system under the sink. Because all Badger model disposals have an inlet for a dishwasher you may or may not use it. If you have a dishwasher then you will need to use the inlet pipe if you do not have a dishwasher then you won’t need to remove the knockout in the inlet pipe for the dishwasher drain.
NOTE: You may or may not need a trap adapter for the reversible J-Bend to slip into this will depend if you already have one on the main drain line. They will come in two forms one will slip inside the pipe and the other will slip over the pipe. If you have a 1-1/2 pipe through the wall but don’t have the trap adapter you will need to pick one up. So look at the pipe coming out of the wall and determine the size.
If it is a 1-1/2 inch pipe nothing on the end you will need to pick up one that slips over the pipe. If your pipe coming through the wall has a coupling over the end of it then you will need to pick up a trap adapter that slips inside the coupling. If you have a 2 inch pipe then you will need a 2 inch to 1-1/2 inch reducer threaded or not choice is yours.
