For a modestly experienced do-it-yourselfer, installing a built-in dishwasher is a pretty simple job requiring only a few hand tools and a spare afternoon.
Be sure your dishwasher's location will allow its door to swing open without hitting an adjacent cabinet or cabinet pulls.
Dishwashers come with the manufacturer's installation instructions; follow these exactly. The directions given here are meant to be a general guide.
Electrical Requirements
A 120-volt electrical receptacle or electrical box that is GFCI (ground fault circuit interrupter) protected must be located nearby, usually at the back of the sink base cabinet.
If needed, have an electrician install or verify a grounded 15-amp receptacle, or you can wire your own.
Plumbing Hookups
The dishwasher must connect to the sink's hot-water supply, usually via a 3/8-inch-outside-diameter copper tube. A flexible drain hose runs from the dishwasher's waste outlet to a tee above the sink's drain trap or to a dishwasher inlet on a garbage disposal (sealed with a "knockout" plug that's removed for a dishwasher hookup).
If your disposal has never been connected to a dishwasher, unplug it or turn off its circuit and use an old screwdriver to punch out the knockout plug, located inside the dishwasher nipple.
The dishwasher can drain directly into the sink's trap if you don't have a disposal. Replace a section of the sink drain's tailpiece with a dishwasher tailpiece, which has a short T-shape nipple that connects to the dishwasher's drain hose.
Cut the bottom of the sink's tailpiece with a hacksaw or tubing cutter and connect the new tailpiece with slip nuts and washers.
Air Gap
To prevent wastewater from draining or siphoning back into the dishwasher, many local codes require that it be connected to an air-gap fixture before the disposal.
The air gap, bought separately, mounts on top of the sink or counter right next to the sink and connects to two flexible hoses--one that runs to the dishwasher's drain, the other to the sink's trap or the dishwasher inlet on the disposal.
In some areas, codes allow looping the dishwasher's drain hose in a high arc up under the countertop as an alternative to installing an air gap.
If your sink doesn't have an unused hole for mounting the air gap, you'll need to bore one in the countertop next to the sink, using an electric drill and a hole saw, or have the sink top professionally drilled.
