How to Fit a Dishwasher

First, make sure the space is ready

A built-in dishwasher needs water, a route into the sink drain and grounded power. We'd settle any missing hookup before removing the old machine, because a replacement with all three hookups already in place is the practical owner-installation route. A first installation also needs its cabinet opening prepared.

Will it fit, and are the hookups ready?

Before removing the old dishwasher, measure width between the cabinets, depth from the back wall to the counter front, and height from the finished floor to the lowest point beneath the counter. Check that the new door can swing clear of nearby cabinets and walls. Compare those measurements with the new unit's required opening.

Find the exact model number on the new machine, carton or order, then open its installation instructions on the maker's model-support page. Compare the required opening, inlet fitting, drain route and limits, cord or hardwire connection, included parts and bracket positions with what you have before buying parts or changing the cabinet.

Standard built-ins are nominally 24 inches wide and about 34 inches high; compact models around 18 inches wide also exist. The new unit's required opening decides the fit. Raised flooring, a mounting strip or a low counter edge can reduce the usable height.

Look under the adjacent sink for a dishwasher shutoff you can reach and close and a supply route. The usual connection feeds hot water, with about 120°F a common target; use your dishwasher's required temperature. A 3/8-inch supply line is common, but its elbow must match the machine and hose. Replace a valve that will not close before disconnecting anything.

The drain needs a disposal inlet or dishwasher sink tailpiece and room for a high loop or countertop air gap. The rise keeps dirty sink water from flowing back. Installation instructions give loop heights of at least 32 or 33 inches above the floor, depending on the machine. Fasten the hose in the adjacent cabinet at the height and location required for your unit, and use an air gap where local rules require one.

For power, use a reachable grounded outlet for a cord-connected unit or an existing supply that matches its hardwire junction box. A grounded 120-volt supply on a dedicated 15- or 20-amp circuit is common. Match the new unit's electrical instructions before connecting it. Missing hookups or needed cabinet changes must be prepared before fitting.

What a new location needs and what fitting costs

For a first installation, measure the opening and plan a route into the adjacent sink cabinet before buying connections. A plumber prepares the hot-water shutoff you can reach and the disposal inlet or dishwasher tailpiece. Settle the high-loop or air-gap choice with the plumbing authority's locally adopted rule before choosing the drain fitting. An electrician prepares the grounded supply, and a cabinet installer changes an opening that cannot fit the chosen machine. Confirm those connections and the door swing before sliding it in.

The first-installation example uses a $34 factory kit for a unit it fits, a $25 to $42 shutoff, a $10 to $15 drain connector, $100 to $150 in circuit materials, two to four hours of plumbing and fitting at $75 to $150 an hour, electrician labor for the circuit, and $150 to $500 to remove one base cabinet. Basic fitting bills two hours at $60 to $125 an hour. Haul-away, the appliance, permits and custom counter or floor work are extra.

Gather the parts and remove the old dishwasher

Gather a tape measure, level, screwdriver or drill, adjustable wrench or pliers, flashlight, shallow pan, towels and floor-protecting cardboard. Inventory the new machine's hose, clamps, brackets and screws. A new 3/8-inch supply line is common. Buy it with an elbow that fits both its compression end and the dishwasher inlet: a washer-sealed 3/4-inch hose inlet takes a different end from a pipe-thread inlet. Buy a cord kit only if the machine permits one. Replace the old supply hose.

If the replacement is used, write down its make, model and serial number from the appliance label. Search the US Consumer Product Safety Commission's recalls (opens in a new tab) for the dishwasher's make and model. Compare its model and serial number with any matching notice; if it is affected, keep it disconnected, follow the stop-use instructions and complete the required remedy before installation.

1. Switch off the dishwasher breaker and close its water shutoff. Confirm that the valve has stopped water flow before loosening a line. For existing hardwire, a qualified person tests a voltage tester on a known live source, verifies that the junction-box conductors have no voltage, then tests the tester on the live source again. The OSHA rule for qualified electrical work (opens in a new tab) requires verification of exposed parts. If that verification cannot be done safely, stop before opening the box and use a qualified electrician.

2. Unplug a cord-connected machine. A qualified person disconnects existing hardwire only after verifying no voltage at its conductors. Put the shallow pan and towels under the fittings, then disconnect the water supply and drain hose; water left in either line will spill.
3. Remove the screws that anchor the dishwasher to the counter or side cabinets. Shorten its adjustable feet and place cardboard in front of the opening.
4. With help, pull the disconnected old machine straight onto the protected floor. Watch its feet and lines so they do not catch or scratch the finish.

Prepare the new machine and guide it into place

Unpack the new dishwasher and locate its inlet, drain hose, power entry and mounting points. Remove packing in its installation sequence, including anything left inside before the first cycle. Fit the supplied brackets. Use a cord kit listed for a unit with a cord connection; a permanently wired unit uses the junction box named in its installation instructions. Keep power off and floor protection in place.

1. Shorten the new machine's adjustable feet for clearance. Follow the model's connection order; for a rear inlet, connect the specified water line, open the shutoff with power off, and check the exposed inlet connection for leaks before sliding the machine in. Feed its water, drain and power lines through the opening into the sink cabinet, then slide the dishwasher inward while your helper draws the excess line through. None of the lines should sit beneath a foot or fold behind the machine.
2. If the dishwasher stops before reaching the cabinet fronts, pull it back out. Look for a trapped hose or cable, an old mounting strip, or raised flooring, and measure the narrowest floor-to-counter height again. Correct the obstruction or choose a machine that fits without forcing the frame or removing its required supports.

Connect water, drain and power

Keep the breaker off and water valve closed while connecting the lines. Their factory arrangement determines which connection you can reach first. Keep hoses and cable clear of feet and moving parts.

For existing hardwire, the electrician verifies that the conductors are de-energized and uses the dishwasher's junction box and strain relief. Enclose the connection before restoring the breaker.

If you connected and checked a rear inlet for leaks before sliding the dishwasher in, skip the inlet steps below. That connection is already complete.

1. With water and power off, identify the inlet and choose its specified 90-degree elbow. Seat the washer or seal if it uses a washer-sealed hose fitting; use a new line that fits the shutoff.
2. Point the elbow toward the supply route and start its threads by hand. If it resists or sits crooked, back it out and restart. Keep standard white thread tape off compression fittings, and follow the inlet and elbow directions for any other sealant and final tightening.
3. Attach the line at the elbow and shutoff without twisting it. Open the shutoff while power remains off and press a dry towel to both visible joints. Both must stay dry under pressure before the machine is tested.

Level, anchor and watch the first cycle

Set the feet firmly on the floor and level the machine side to side and front to back. Center its door against the cabinet fronts. The gaps should look even, and the door should open and latch without rubbing.

1. Secure the leveled machine with its supplied brackets and screws. Mount upward into wood above it, or use the machine's side mounting points for stone or another counter that should not be drilled. The machine should stay put when its door opens.
2. Before testing, confirm that the drain is clamped, the high loop or air gap is in place, the water valve is open, the visible supply fittings are dry, the hoses are clear, the power connection is closed and the brackets are secure. Restore power.
3. Leave the lower access area visible and run the machine's installation test or an empty cycle. Watch it power on, fill, wash and drain. Look at the supply and drain joints and the floor during and after the cycle; they should stay dry. Fit the lower access panel only after all of those checks pass.

If the first test leaks or stalls

1. If water appears during the test, stop the cycle. From a dry location, turn off the breaker and water valve before touching a connection; leave both off while an active leak remains. For a leak at a visible new fitting, dry the area and locate the exact joint. Inspect its hose, seal, seating and clamp. Refit or replace the faulty connection, open the water valve and look for drips. Once the joint stays dry under pressure, restore power and run one watched empty test. It has worked when the fitting stays dry through fill and drain.
2. If the machine will not start, confirm the breaker or plug supplies power, the door latches fully, and a cycle is selected without a delay or control lock. Trim or insulation caught at the latch can keep the door open. Try the cycle again; a normal start shows that the installation or setting caused the failure.
3. If it starts but will not fill, make sure the water shutoff is fully open. Isolate power before looking behind the lower access area for a kinked or pinched supply line. Free the line, restore power and run one watched empty test; water entering the tub with dry fittings confirms the correction.
4. If it will not drain, isolate power and inspect the drain hose where the machine could be sitting on it. Straighten any crush or kink, confirm the required loop or air gap and clear sink connection, and remove a new disposal inlet's knockout if it remains. Restore power and run a repeat empty cycle; it should drain through the sink connection without a leak. Do not put drain cleaner in the dishwasher.

Stop testing if a refitted joint leaks again or the correctly connected machine still will not start, fill or drain. Call the installer for a new connection defect, a plumber for a valve or sink-drain change, an electrician for power work, or a cabinet installer for an opening change. A leak from inside the machine or another internal fault goes to warranty service or an appliance technician. Give them the make, model, installation date, hookup type, failed test stage and checks already made.

A first installation beside a disposal with a new dedicated circuit and one base cabinet removed runs $670 to $2,310 for fitting and site work; the appliance, permits and custom counter or floor work are extra. An out-of-warranty diagnostic visit runs $70 to $150 before a separately quoted repair.

For problems after normal use, follow our leaking dishwasher checks or dishwasher drain checks.

Questions before you finish