Installing a built-in dishwasher requires basic mechanical, electrical, and plumbing skills, so the average handyman can install a dishwasher in 1-3 hours, depending on whether it’s a new installation or a replacement dishwasher. If you are replacing an existing dishwasher, it will take less time.

New installation

1. Prepare the cabinet area where the dishwasher will be installed. The opening must be 24″ wide for most models, 24″ deep, and 34 1/2″ from the floor to the bottom of the counter. The back wall cannot have pipes or wires. Supply lines Power and water will come into the cabinet in the 4″X4″ area at the bottom rear of the cabinet through a 1 1/2″ hole. Make sure the floor is level and the cabinet is square.

2. Choose your drainage method based on local codes and the height of the drain tee. Some codes require an air gap. If the drain tee is less than 18 inches from the floor, you must use an air gap. If an air gap is not required and the tee is more than 18 inches from the floor, you can use the loop method for the drain connection. If the drain hose will connect to a garbage disposal, you must remove the dummy plug for the dishwasher to drain.

3. Check or install wiring making sure there is a dedicated 120V, 60Hz circuit with a 15 or 20 amp circuit breaker or time delay fuse. Wiring must be 2-wire with ground and rated for 75 degrees Celsius or 176 degrees Fahrenheit. Wiring can enter the cabinet from either side in the lower rear area. The hole must be a maximum of 1 1/2″, and can be the same hole used for the water supply line and drain hose if it is hardwired. If it is a flexible power cord, it must have a separate hole Wiring The wire will run up the right side along the bottom 24 inches of the cabinet to the dishwasher’s right front electrical connection.

4. Prepare the water supply line that enters through the 1 1/2″ hole in the bottom rear of the cabinet. Turn off the water to install a manual shutoff valve under the sink. The water connection is at the left side of Use a 3/8″ OD copper line to extend a minimum of 19 inches from the rear wall. The water heater should be set between 120 and 150 degrees (closer to 120 if there are children in the home to avoid scalding accidents) and the pressure should be between 20 and 120 PSI.

5. Prepare the dishwasher by checking the balance of the door and adjusting the spring tension if necessary. If legs need to be attached, do so close to where it will be installed.

6. Connect drain hose to dishwasher drain port if not factory installed. Route electrical wiring and water supply lines so they are not caught by the bottom of the dishwasher. Slide the dishwasher in front of the opening so you can thread the drain hose through the hole you drilled.

7. Slide the dishwasher inch by inch into the cabinet while feeding the drain hose through its hole. Stop with a few inches remaining and make sure nothing is twisted or pinched. If everything is in good shape, push the dishwasher all the way in so that the edges of the door are behind the cabinet frame. Test the door to open and close smoothly.

8. Level the dishwasher front to back and side to side by adjusting the leveling feet.

9. Align brackets and secure dishwasher to countertop according to manufacturer’s instructions.

10. Through the access panel, connect the water supply line and the electrical supply. Also connect the drain hose under the sink. You are ready to do a wet test with the “rinse only”
cycle. Check for leaks and proper drainage.

Replacement of an existing dishwasher

You will not need to drill the holes as they will already be there from the existing dishwasher. However, you should inspect the wiring and plumbing to make sure they can service the new dishwasher. Once that is established, you should turn off the main power and turn off the water supply before you begin removing the old dishwasher. All lines and cables must be disconnected first. Remove the drain hose from the garbage disposal or the drain pipe under the sink. If the dishwasher has a power cord, you must unplug it. If the dishwasher is hardwired, you must open the access panel and electrical junction box. Remove the wire nuts and disconnect the black and white wires. Also remove the ground screw to disconnect the green ground wire. Use a catch pan while disconnecting the water supply line. Once all of these lines and wires have been disconnected, you can remove the screws and brackets holding the dishwasher in place and carefully remove the old dishwasher.

Then follow the same procedures to install the new dishwasher with the exception of drilling the holes and running the wiring and water supply lines.

Once you’ve installed your new dishwasher and tested it for leaks, you’re ready to start cleaning.