Install a Dishwasher

Dishwashers slip into a 24-inch cavity under your counter and disappear behind a cabinet door, but the connections behind them need precision. You're routing pressurized water, managing drainage slope, and making an electrical junction—three systems that have to work quietly and leak-free for years. The difference between a solid install and a callback isn't the mechanical difficulty—the box slides in, the screws go through brackets—it's in taking the time to get the rough-in right before you push the unit into place. The work happens in two distinct phases: roughing in the utilities while you still have room to move, then sliding the dishwasher into position and making final connections. Most installs replace an existing unit, which means you're working with established lines. If you're adding a dishwasher where none existed, you'll need to run new plumbing and electrical—a different project entirely. This guide assumes you're swapping units in an existing opening with hookups already present.

1. Kill Power and Water First. Turn off the water supply valve under your sink, usually on the right side near the back. Flip the circuit breaker for the dishwasher—if you're not certain which breaker it is, flip them until the outlet under the sink goes dead, confirmed with a voltage tester. Open the dishwasher door and remove the lower rack and spray arm to access the mounting brackets at the top corners of the opening.
2. Pull Old Unit Out Clean. Loosen the mounting screws at the top of the unit where it attaches to the underside of your countertop. Under the sink, disconnect the drain hose, water supply line, and electrical connection. The drain hose typically connects to the garbage disposal or a sink tailpiece. Pull the dishwasher straight out, tilting it slightly back to clear any leveling feet that might catch.
3. Verify All Rough-In Lines. With the opening empty, inspect your water supply line, drain connection, and electrical box. The electrical junction box should be in the cabinet adjacent to the dishwasher opening, usually on the right side. If your water supply is rigid copper, replace it with a braided stainless supply line for easier connection. Confirm your drain hose has a high loop—it should rise to just below the countertop before dropping to the disposal—to prevent backflow.
4. Wire and Plumb the Unit. Tip the new dishwasher on its back on cardboard. Attach the 90-degree elbow to the water inlet valve at the front left of the unit—use two wraps of Teflon tape on the threads. Connect your braided supply line to this elbow. Attach the drain hose to the discharge port with a hose clamp. Remove the electrical cover plate, feed your electrical cable through the strain relief connector, and wire black to black, white to white, ground to green.
5. Slide and Level Carefully. Feed the supply line, drain hose, and electrical cable into the opening first, then carefully slide the dishwasher in, keeping lines from kinking. Stop with the front face 1/4 inch behind the cabinet face—you'll pull it flush with the leveling feet. Adjust the front feet by turning them with pliers until a level placed on the door shows plumb both ways. Back feet usually self-adjust.
6. Seal All Supply and Drain. Under the sink, thread the water supply line onto the shut-off valve hand-tight, then one more turn with a wrench. Connect the drain hose to the disposal inlet or air gap, securing with a hose clamp. Turn the water supply back on and check for leaks. Restore power at the breaker. Open the dishwasher door and run a short rinse cycle while watching underneath for any water weeping from connections.
7. Secure and Test Fully. With connections confirmed leak-free, drive mounting screws through the upper brackets into the underside of your countertop. These screws keep the dishwasher from tipping forward when the door is open and loaded with dishes. Attach the toe kick panel at the bottom front. Replace the spray arm and lower rack. Run a full empty cycle to confirm drain performance and listen for unusual noises.
8. Balance Door Spring Action. Open the door to 45 degrees and release it—it should stay in place or close slowly. If it drops hard, the door spring tension needs adjustment. Access the spring mechanisms on the sides of the unit behind the side panels and adjust according to your model's instructions, usually by rotating a tension arm. A properly balanced door reduces wear on hinges and prevents damage to dish racks.