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The Home Depot

How to Install a Dishwasher

Pro Referral > Home Guides > Appliance > How to Install a Dishwasher
How to Install a Dishwasher

Table of Contents

  1. Tools and Materials
  2. Considerations
  3. Selecting a Dishwasher
  4. Locating your Dishwasher
  5. Prep the Dishwasher
  6. Preparing for Electrical Connections
  7. Prep the Cabinet Opening
  8. Prep and Install the Drain Line
  9. Connect the Supply Line
  10. Making Final Electrical Connections
  11. Level and Mount the Dishwasher
  12. Conclusion

It’s hard to imagine cleaning up in a kitchen without a dishwasher. With far ranging options, you'll find dishwashers that are built-in or portable, compact or full-size.

Joining white, black and stainless, models which accept panels allow units to blend seamlessly into surrounding cabinetry. Beyond aesthetics though, engineering and design in recent decades has produced some exceptional advancements, including energy-efficient, ultra-quiet, and even stacked or drawer-type models.

With respect to wheel-around units and slim 18-inch options (both great for small apartments or home bar installations alike), the most universally available and widely popular dishwashers are 24-inch built-in models. Because of this, our article here will focus on installing just that - the 24-inch, integrated dishwasher.

While all that are marketed as such of course have a nominal size of 24 inches, make sure to check the exact dimensions of your selected appliance (as some will vary just so slightly). Before beginning installation, always check the exact measurements, too, of the dishwasher's available kitchen cabinet opening.

    1. Tools and Materials

    Below, you'll find the tools and materials needed to complete your dishwasher installation.

    Tools Materials Skill Level Estimated Time
    • Multi-driver (Screwdriver set) • Dishwasher (with air gap) Intermediate 2 to 4 hours
    • Adjustable wrench • Dishwasher drain hose (with spring clamp or similar)
    • Channel-type pliers • Branch fitting (drain if no garbage disposal present)
    • Tubing cutter • Dual outlet supply shutoff
    • Utility knife • Braided water supply line
    • Wire stripper / pliers • 15 amp circuit (15 amp circuit breaker 14-gauge Romex cable)
    • Drill driver 1 ¼” - 1 ½” or 2" hole saws • Wire nuts (sometimes included with dishwasher)
    • Tape measure • Wire clamp
    • Torpedo and two-foot level • Wood or drywall screws
    • Teflon tape

    2. Considerations

    In a large number of cases, installing a new dishwasher will amount to nothing more than replacing an existing dishwasher. In these situations, much of the required design and prep work will already be completed for us. (Note: When removing an existing dishwasher be sure to dispose of it in accordance with local laws.)

    In the context of a remodel, and as with the other appliances found in most American kitchens, installing a dishwasher will summons both your plumbing and electrical skill. Because a dishwasher installation touches on these regulated home systems, it is always a good idea to check with your local building authority for any requirements that may govern its installation.

    Still other installations may call for a retro-fit into an existing kitchen. Likely the most challenging of all installs, retro-fitting a dishwasher may require a rework of existing cabinetry, countertops and/or other fixtures. Always perform due diligence, taking into consideration your specific circumstance, and thoroughly research the model you select prior to the day of install.

    Important! The steps provided below could and should be re-ordered such that they make the most sense for your given project.

    3. Selecting a Dishwasher

    In this day and age, multi-cycle models are a given. On higher end units, you may find controls located on the top or the side, but more common, you'll see them on the unit's face - its door. Most, though not all, will open downward, hinged at the bottom, their doors containing needed compartments for dishwasher detergent and other cleaning agents.

    The tech is broad and varying, but in general the better models offer intelligently designed cycles targeting not only greater cleaning flexibility but also a high degree of energy / water efficiency. The best models yield greater dirty water pumping and waste-removal capacity, yet run super quiet. Ideally, the dishwasher you select should roughly coordinate with the other appliances in your kitchen, but ultimately, it must serve your situation as outlined above.

    4. Locating your Dishwasher

    In the context of a remodel, placement is key. While modern design has produced broader flexibility in locating dishwashers, they are always still set within a few cabinet-widths of primary plumbing connections. Because of this, you'll find them most commonly installed immediately adjacent to the kitchen sink (itself central in cleanup tasks).

    Ideally, corners are avoided. Again because common configuration has a dishwasher door swinging downward open, make sure to consider your opened dishwasher’s footprint and how it might interact with surrounding cabinetry and natural walkways.

    No-stoop dishwashers are sometimes seen. In this installation, the base of the dishwasher sits atop a riser, helping to minimize the bending required in loading it. That said, standard dishwashers are still designed to sit below a 36-inch tall, 25-inch deep kitchen counter.

    5. Prep the Dishwasher

    After unboxing your new dishwasher and retrieving its installation manual, remove all packing. It's at this point that we'll pre-connect our plumbing supply and drain lines. Almost without fail, dishwashers are fitted with a kick-space plate, allowing ongoing access to plumbing and electrical lines once the dishwasher is set. If your dishwasher comes shipped with this bottom plate pre-installed, remove it with a ratcheting multi-driver. In most cases, a ¼” hex nut driver will work with removing and re-installing this panel.

    Employing the cardboard from the dishwasher's carton spread out as floor protection, gently tip the dishwasher onto its back such that you can access the drain pump outlet and supply inlet fittings. Most dishwashers will come with both padding and plugs installed. These are used to cap and protect the unit’s drain and supply connection points during shipping. If needed, use a pair of needle-nose pliers to carefully remove these caps, and then discard them.

    Installing the drain hose to the dishwasher’s discharge pump is a relatively easy task. Some dishwasher makers will provide a modest pre-packaged drain hose, but because installation configurations can vary greatly, longer lengths and extension kits can be found at your local home center. Standard drain hoses are typically about six foot long, are sized at 5/8th of an inch, and will require either a spring clamp or a No. 6 hose clamp for connection.

    To start, slip your selected clamp onto the hose’s pre-formed end and wiggle the hose firmly onto the drain’s outlet (usually a nipple that extends a few inches from the pump). Slide the clamp into place and snug it down.

    Now install the dishwasher supply line. Most dishwashers will come pre-equipped (or at least supplied) with a brass reduction L-fitting. If this L-fitting is not pre-installed, install it now. Wrap its threads with a bit of teflon tape, and screw the fitting into the water inlet. Two wrenches are wise here. A large set of channel-type pliers can be effective at stabilizing the water valve as you tighten down the fitting with a small adjustable wrench. Note: Be conscious of how this elbow orients as the water supply line will of course pass to / run from it.

    Braided supply lines designed specifically for dishwasher installs are also available at home centers and commonly run in 36- 48- and 60-inch lengths. (Make sure that you select one that is not only appropriate for your installation, but also allows some slack for the rare event that the unit must be pulled for future servicing.) Flexible braided supply hoses provide the literal flexibility required for this project. Connections are made by way of compression fittings (off-the-shelf, in a 3/8” size).

    Hand-tighten compression connections and finish with a strong quarter-turn from an adjustable wrench. When tightening the connection down, again work with two wrenches. Refer to manufacturer's installation instructions as some may require additional actions for prepping the supply side’s filler tube. Execute these steps as needed.

    Locate and remove the cover from the unit's electrical box and set aside. If this box is fitted with a knock-out that will later accept cable clamping, proceed to knock it out.

    6. Preparing for Electrical Connections

    During a dishwasher install, the electrical supply can be configured in one of two ways. A line can be run directly from the home's breaker panel to the dishwasher, where it is hard-wired in. Alternatively, you may install a dedicated appliance receptacle. A 12-gauge appliance cord is then wired into the dishwasher and later plugged into a dedicated wall outlet. In most cases, wiring directly to the dishwasher (if manufacturer's instructions allow) is preferable.

    The dishwasher should be connected to a 125-volt, 15-amp circuit. If wiring new, this means it must be fed with a 14/2 NM wire with a ground. (You may elect to feed the dishwasher with a 20-amp circuit using 12/2 NM wire.) When wiring, add about two feet to your wire run, this slack too will allow for ease in future servicing.

    Dishwasher makers typically provide a built-in junction box within which electrical connections are made. This junction box is typically, but not always, found on the side opposite of the water supply line connection point behind the front bottom panel in the dishwasher's kick space area.

    If choosing to connect an appliance cord and plugging it later into a dedicated appliance receptacle, connect your appliance cord while your dishwasher is still tipped on its back. You’ll often set up to feed the appliance cord into the sink base cabinet, locating the dishwasher’s outlet itself also inside.

    Consult with an electrician if you have questions with running a new dishwasher circuit. Prep for your connection in one of the two fashions described above and feed the direct wire into the dishwasher bay or plan to feed the now fitted appliance cord through a hole (which we will later make) in the sidewall of the sink base cabinet.

    If choosing to direct wire, make sure that the circuit is off at the breaker panel as you work. Extend your wire into and out through the dishwasher opening, temporarily taping it to the floor with blue painters tape. This will help immobilize the wire, avoiding damage to it as we work.

    7. Prep the Cabinet Opening

    With a bank of cabinets already set, check the dimensions of the opening provided for the dishwasher by measuring at three points – top, middle and bottom. While most dishwashers size down slightly, it is always wise to check the appliance’s exact dimensions again at this point. When in doubt you should ensure that your cabinets’ dishwasher opening measures 24 1/16 inches in width. This extra 1/16 of an inch can come in handy if dramatic adjustments in level are required side to side.

    With a new cabinet installation, we’ll plan to drill a two-inch hole near the back bottom of the sink base sidewall. Ideally, drill using a drill-fitted hole saw from both the outside and the inside of the cabinet to prevent tear out. Dishwasher design will dictate the exact location and size of/for this hole, but a common placement will locate it roughly three-inches from the floor and two-inches off the nearest back wall. This is the location through which drain, supply and sometimes electrical lines will pass.

    When drilling, be mindful of both the sink base’s floor as well as manufacturer requirements. In some cases, a second hole may be required in the sink base’s inside bottom.

    Find the front to back clear paths for plumbing and mark them out on the floor. We’ll work to keep lines in these raceways so that do not get caught up in the appliance’s motor or other moving parts.

    Tip the dishwasher again upright, and still on its cardboard, slide it into its rough location at the front of its intended bay. Rough level it, starting with the back legs - front to back then side to side (be prepared to make additional adjustments after plumbing connections are made and before the dishwasher is attached to counter/cabinets later.) Route the now-attached drain and supply lines through our cabinet drilling from above; ensure that they remain true to our raceway spaces marked out above.

    Slide it fully into its opening, pulling the slack of the drain and supply lines into the sink’s base cabinet.

    8. Prep and Install the Drain Line

    A dishwasher drain is sometimes looped up to a device called an air gap. Air gaps have been historically installed through the countertop and covered with a vented cap. The air gap works to prevent dirty water from backing up into the dishwasher if the sink drain perhaps gets clogged.

    Some self-rimming, drop-in sinks come pre-drilled for an air gap. With other configurations, the counter itself will require a drilling. The air gap passed down through the counter top and locked into place using a washer and nut pair installed from underneath. Tighten the air gap mounting with a basin wrench or a set of angled pliers.

    If your sink includes a garage disposal, and you are utilizing an air gap, your dishwasher will connect to it after first detouring to the air gap. Without fail, disposal manufacturers provide a built-in nipple, an inlet for connecting a dishwasher drain. If no dishwasher had been previously installed, a knock-out will appear inside this nipple at the inner face of the disposal wall. Use a flat head screwdriver and hammer to, well, knock it out.

    If no disposal is present, the dishwasher drain connection will be made by way of a Y-shaped extension jetting from the sink drain's tailpipe. If this is the case, and there in not one already in place, plan to purchase and install an appropriate 1 1/2” kitchen drain tailpipe.

    If you have not already, it is worthwhile to check local building codes here. Some municipalities allow for bypass of the formal air gap. As typical air gap installations jump up through countertops, and can be somewhat unsightly, many choose instead to simply loop the dishwasher drain hose inside the sink base cabinet. With this, the loop must run up to a point higher than the sink’s drain. Attach this air loop to the inside of the cabinet with appropriate plumbing strapping.

    Regardless of whether there is a disposal in your setup, whether you choose to employ a formal air gap or not, plan to make drain connections using an appropriately sized spring or ratcheting hose clamp. Drain hoses may typically be trimmed to needed length using a utility knife. Take care not to either kink the line or inadvertently wrap it around other sink elements like a pull-out sprayer hose.

    9. Connect the Supply Line

    A dishwasher’s supply line is most often branched from and connected to the sink's hot water supply line. By connecting to the hot side of the water supply, utilizing a dedicated water shutoff, we minimize the work that the dishwasher’s heater must do during certain wash cycles. The supply runs to and connects to dishwasher's water valve found again near the front of dishwasher, immediately behind a dishwasher’s front bottom panel.

    If your sink’s hot water riser does not contain a shutoff for your dishwasher, as in the case of swapping out an existing dishwasher, install one. Shutoff valve configurations can vary based on the supply tube’s material. If branching from copper or cpvc, as is often the case, select brass shutoffs with compression fittings. Independent shutoffs or a dual-outlet shutoff may be installed.

    Once your shutoffs are in place, connect the water supply line designated for the dishwasher. Connect compression fittings again using two wrenches. No need for teflon tape - hand-tighten, then a quarter-turn.

    10. Making Final Electrical Connections

    With water connections made, move again to the front of the dishwasher.

    If you selected to direct wire, slide a cable clamp up over your pulled electrical wire. Feed about six inches of it through the junction box’s feeder opening and loosely secure both the clamp to the box and the clamp to the wire. Strip first the outer sheathing of insulated cable. With wire strippers, then strip about a 1/2" of insulation from both the black and white wires found within the cable.

    These will be tied in kind to black and white leads found within the dishwasher's wiring panel. Ground wires are wrapped and then tied down to the box's ground screw, often green in color.

    Once connections are made with appropriately sized electrical wire nuts, fully tighten the connecting cables star nut using either pliers or a flat head screwdriver. Double check and tighten if needed the connection clamp to your insulated cable. Replace the electrical box’s cover.

    11. Level and Mount the Dishwasher

    While you may be tempted to fill the hole in your base cabinet with spray foam insulation, it may be wise to leave out for easier servicing later.

    Important! As you move the dishwasher into its final resting position, ensure that the dishwasher's insulation is not disturbed. This wrapping is important, as it serves to quiet the tub when the dishwasher is in use.

    Leveling a dishwasher is often accomplished with four independent leveling legs. Each has the ability to shift the unit to the left and to the right. Two legs at the back will raise or lower the back of the unit. The two level legs at the front raise or lower the front of the appliance. Working with both a torpedo level, set atop of unit’s door, and with a two-foot level, held against the face of the dishwasher’s tub, plumb and level the appliance flushing it up to both surrounding cabinets and the countertop.

    Most dishwashers will supply brackets that allow for mounting either to the countertop above or to the cabinets on its sides. (Some will come pre-attached; others may not.)

    Typically mounting to the counter is the most inconspicuous option, however, depending on the countertop material (granite for example), screwing directly into the countertop is not an option. In these cases, consider epoxying either appropriate hardware or a strip of scrap wood in place. These will make mounting possible. Supplied brackets are, to an extent, bendable to make up for small inconsistencies in the opening. If at all possible, employ flat phillips head screws when securing the unit to wood or other hardware.

    Flip the appliance's power on and run a test cycle according to manufacturer recommendations. Check both for proper operation and to ensure that no leaks appear. If a water leak is identified, tighten compression fittings slightly on the supply side; tighten hose clamps on the drain side - whichever is appropriate.

    Re-install the dishwasher's kick space panel once you are satisfied with your work.

    12. Conclusion

    Like other kitchen appliances, dishwasher installation is often accompanied and guided by a very detailed set of specific instructions. You will be well served by studying the manual provided with your selected dishwasher. Employ additional information as needed that is specific either a. to the appliance you purchased and/or b. to your given installation situation.

    While not much above a beginner level DIY job, you can serve yourself well by grabbing a helper for this job. Because it touches on elements of both electrical and plumbing, it is best to brush up on needed skills before you begin. If you get in trouble of course, consider consulting with a local professional.

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