Although not the most glamorous kitchen improvement, the addition of a garbage disposal will be greatly appreciated by the chef of the house. Because disposals vary greatly in size and bowl depth, check the dimensions to make sure the disposal you've chosen will fit under your sink.

Since installing a disposal often requires both plumbing and electrical skills, it's a project best taken on by experienced do-it-yourselfers or appliance installation pros. Unless you are replacing an existing garbage disposal, one tricky task is installing a GFCI (ground fault circuit interruptor) outlet under the sink to provide power to the disposal and installing a switch adjacent to the sink to control the outlet.

Instead of  wiring a conventional electric switch, a good option is to utilize an "air switch." You can plug the disposal into this simple little device and then plug the air switch into an existing outlet; it is controlled by a small button that you can mount nearby on the countertop or cabinet. Another option is to use a remote-control switch.

Always shut off the power to the circuit that will serve the disposal before beginning any work. If you're replacing a disposal, turn off the electricity to that circuit and unplug the disposal or disconnect the wiring before removing the unit. Test the bare ends of the wires with an electrical voltage tester to make sure they are not charged. To provide better access and make the work easier, you may be able to temporarily remove the cabinet doors under the sink. When working under the sink, wear safety glasses.

1) First, disconnect and remove the existing waste assembly, from the sink flange to the trap. Have towels and a bucket handy to catch water and debris. Once the waste lines are out of the way, remove the mounting assembly from the disposal, and install the new flange in the sink hole, applying a coil of plumber's putty around it before dropping it into place, as shown.
2) Attach the upper mounting assembly to the sink flange, placing a heavy object such as a large phone book on top of the flange to hold it in place. Follow the manufacturer's directions for gasket placement, and slip the mounting ring over the flange. Then, slide the snap ring onto the flange until it pops into the groove on the flange. Next, tighten the three mounting screws, as shown, until the assembly has a tight seal against the sink.
3) To get ready to attach the disposal to the mounting assembly, first attach the discharge tube, as shown. Then inspect the P-trap, and clean out any hardened waste. Next, prepare the dishwasher drain connection. This usually entails knocking out a drain plug from the dishwasher nipple and attaching the drain hose from the dishwasher.
4) Position the disposal under the mounting assembly so that the mounting tabs can slide over the mounting tracks. Lift the disposal, and insert the top into the mounting assembly. Rotate the lower mounting ring until all three mounting tabs lock over ridges in the mounting ring. Use the wrench provided or a screwdriver to tighten the ring.
5) Rotate the disposal so that the discharge tube aligns with the drain trap. If your sink is a double-bowl model, you'll need to replumb the wasteline to attach to the disposal. If you're lucky, all you'll need is an extension tube. If not, you may need to replace the entire assembly, shown here.
6) Finally,connect the disposal to power. Either run a line or have a licensed electrician install a switched  GFCI receptacle. Or buy an air switch or remote control switch as mentioned above. If your disposal didn't come with a plug on the end of the cord, wire the recommended grounded electrical cord to the disposal. Plug it into the receptacle (or into the air switch or remote-control module).

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