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Home Improvement, Kitchens and Baths, Repairs and Installation Published 04/10/2008 by Jared Libby
Whether you’re putting in all new appliances or simply replacing a worn-out machine, installing a dishwasher yourself is a DIY project that’s not that difficult and can save you a hefty installation fee.
The first step is making sure the machine will fit in the opening. Most standard dishwashers require a 24” opening. If you’re installing new cabinets, it’s important to consider the width of the dishwasher ahead of time. The height of most machines is adjustable.
Depending on your cabinet configuration, you may need to drill one or more holes to run supply lines, electrical wiring, and the drainpipe through. Hole saws make quick work of drilling larger diameter holes.
Remove the faceplate at the base of the machine to access the supply line inlet and electrical box. It’s a good idea to connect the wiring, drain, and supply lines before pushing the dishwasher into the cabinet, since it makes it easier to access the underside of the machine.
Start by connecting the drainpipe to the discharge pump. Many local building codes require dishwashers to be vented using an air gap to prevent the siphoning of water from the sink drain or disposal. Mount the air gap in one of the sink holes or drill a hole for it in the countertop. Connect the drainpipes to the air gap and secure them with hose or spring clamps.
If an air gap is not required, loop the drain hose up near the top of the base cabinet, and attach it to the wall with a strap to prevent backflow from the sink.
Run the drainpipe to the inlet of the garbage disposal and secure it with a clamp. Many garbage disposals have a plug in the inlet, so be sure to remove it first.
If there isn’t a garbage disposal or an existing drain for the dishwasher, replace the drainpipe under the sink with a dishwasher branch tailpiece and install it above the trap under the sink.
Most dishwasher supply lines are 3/8” diameter, but check to make sure you’ve got the right parts before starting the job. Begin by turning off the water and installing a dual outlet shut-off valve to connect the dishwasher supply line to the hot water pipe under the sink. One outlet on the valve provides hot water for the sink faucet while the other attaches to the dishwasher supply line. This will allow you to turn the water off to the dishwasher separately from the faucet.
Connect one end of the supply line to the shut-off valve and the other end to the water inlet on the underside of the dishwasher using a right angle elbow.
Where needed, apply Teflon tape to the male threads to prevent leaks. Supply lines should be hand tightened then given a solid quarter turn with a wrench.
Always be sure to cut off the power to the dishwasher by flipping the circuit breaker before attempting to connect the electrical supply. Run the cable through the back of the electrical box on the dishwasher, and connect the hot (usually black) and neutral (white) wires to the corresponding wires in the box using wire nuts. Be sure to connect the ground wire to the green screw and replace the cover on the box.
Turn the water back on and check for leaks, then turn on the power and run the dishwasher through a full cycle. If everything works properly, slide the machine into the cabinet, being careful not to crimp or pinch the pipes. Plumb and level it by raising and lowering the adjustable feet on either side.
Screw the dishwasher to the underside of the countertop to hold it in place. When attaching the mounting screws to the plywood used to support a stone countertop, be sure the screws do not protrude into the stone.
Attach the faceplate to the base, and your new dishwasher is ready to go!
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May 7th, 2008 at 9:14 am
This is the most helpful article. I am putting in a dishwasher tonight and I’ve got this bookmarked. Thank you for your website and thank you Mr. Libby for a great article.
May 12th, 2008 at 3:54 pm
How far can you install a dishwasher from the sink and still have it work properly?
Ben Erickson Says:May 22nd, 2008 at 1:52 pm
The maximum distance the dishwasher can be from the sink drain will vary depending on the make and model, but should be spelled out in your manual. Usually they range from 5′ to 10′.
May 22nd, 2008 at 11:14 pm
I’m trying to take out my dishwasher from the sink to see where is the smell of cigratte is coming from because I have neighbor that smokes and I could smell it through the sink where my dishwasher is place so if there is any tips on where or what I could do to prevent this smell please help.
Thanks
June 4th, 2008 at 1:56 pm
I am trying to replace my dishwasher. When I took the old one out I notice the electrical wire was plugged into an oulet that just laying on the floor, under the dishwasher. The drain hose was also laying on the floor. Is this common practice? Can the elecrical outlet be placed behind the diswasher? Or does it have to go in the cabinet next to the dishwasher openning. What about the drain?
June 6th, 2008 at 2:06 pm
I’m installing a new dishwasher and someone told me that you must have the drain up high above the sink trap, is this correct. Someone else said that it’s allright to just let it drain by gravity into an existing drain line running along the joists in the basement. I would appreciate your info on this.. thanks , ED
June 6th, 2008 at 9:27 pm
After my dishwasher was installed, I noticed that the faceplate was protruding beyond the cabinet. Is this correct? Should the dishwasher be pushed in to the cabinet further and then reintall the faceplate?
Ben Erickson Says:June 9th, 2008 at 11:22 am
Hi Ed,
Since dishwashers use a pump to drain, gravity is not needed. As noted in the article above, the drain hose should either have an air gap mounted on the kitchen counter or loop up near the top of the base cabinet to prevent backflow from the kitchen sink. Also, be sure to attach the dishwasher drain line above the sink trap to keep sewer gases from coming through the drain line.
June 20th, 2008 at 12:14 am
Here’s an odd thing: I had a new dishwasher professionally installed a few months ago and we had a drain problem almost immediatly (cleared with Drano) and now I’m finding what looks like white particles in all the faucet screens everywhere in the house. They look and smell like dishwasher soap. Any idea what is happening here?
June 21st, 2008 at 11:55 am
Doug,
June 20th, 2008 at 12:14 am
Perhaps you turned the water temperature up on your water heater. I think these white pieces are coming from the water heater. I have seen some white plastic pieces in the aerators which ended up being the cold water dip tube inside the water heater. It was breaking up. Dishwasher soap cannot get into the water supply. Hope this is useful. Karl
July 1st, 2008 at 10:55 pm
Doug,
IMO;
If you are finding “white particles” in the aerators of your faucets you should probably first consider calling a Licensed Professional Plumbing Contractor whom KNOWS how to propery service this device / knows what I suggest herein and after you tell him the symptoms he need be able to recite what I speak of here before you allow him in for repairs! The Contractor should be skilled in looking at the “DOWN TUBE” on the cold water inlet to the water heater which is a good 4′ or so long. Doug there were hundreds of thousands of DEFECTIVE down tubes installed in MANY water heaters some time ago. The defective down tubes basically disintegrate into tiny white particles and must be replaced, a tell tale sign this is, but not the ONLY diagnosis as well, certainly the most plausable.
If your water heater is older than 5 years old I would suggest just replacing it Vs. fixing it Doug if the down tube is found defective. Water heaters simply do not last as long as they used to and if your get 5 years out of a water heater anymore your doing GOOD. BELIEVE IT.
The down tube in question delivers cold water to the bottom of the water heater and w/o it your water heater will not function correctly Doug and this condition could COST YOU MONEY and heartache. Remember hot water rises so it only makes sense to deliver the cold water coming into the tank to the bottom, yes? YES! Check it, the down tube out, and fix as necessary and SAVE FUEL COSTS Doug.
DO not expect to be able to re-use the flexible water connector (2) you may see up there, get anew BEFORE you touch them Doug. The’re only designed to be used one time and reuse is asking for trouble. Your licensed professional plumbing contractor will NEVER re-use items such as these.
Regards and Good Luck Sir;
BRAD DAVIS
Master Plumbing Contractor
July 7th, 2008 at 2:12 pm
I just had a new Dishwasher delivered. The old supply line would not connect to the new 3/8 inch elbow joint under the dishwasher. I went to Lowes and bought a new braided 3/8 inch supply line that connects to the elbow piece but it would not connect to the water supply valve. I even tried a 1/2 inch connector but that was too large. Any suggestions?