Dishwasher Installation


How to Install a Dishwasher

Installing your own dishwasher may not be a project that every homeowner will want to undertake, although if you are simply replacing an old dishwasher, the steps involved should be quite simple.

New dishwasher installation considerations

  • Permits may be required
  • There are plumbing connections to be made on the hot water lines and connections to the drainage system.
  • Electrical hook-ups must be made.
  • Carpentry considerations for new installations.

Tools you may require

Drill, Hole saw or 1" spade bit, Soldering equipment, Hacksaw, Screwdrivers, Wrenches, Wire strippers, Hose clamps, Teflon tape, Wire nuts, 48" braided dishwasher supply, 3/8" male threaded 90 elbow, solvent cement, primer, and Measuring tape.

Before you buy a dishwasher

Make sure there is adequate space for a built-in dishwasher or a stand alone model. If all of your cupboard space is full, you will have to remove a section or extend the counter top by about 24 inches for the average built-in dishwasher (other sizes are available).

Once you have the open space available, now would be a good time to install the electrical connections and plumbing connections, before your dishwasher arrives.

Dishwasher electrical connections

A standard residential dishwasher should have a connection to a 120 volt, 20 amp circuit. This can be made with an extension cord if your not comfortable with performing electrical work (hiring a certified electrician is highly recommended).





Dishwasher plumbing connections

Water supply

  • Dishwashers must be supplied with hot water, so you will need to cut a tee into the nearest hot water line to the dishwasher's location.
  • Dishwaher water supplyShut off the water to the branch nearest the dishwasher or your home.
  • Cut the hot water line and install a 1/2" tee or 3/4"x3/4"x1/2" tee and solder or glue/cement in enough pipe to reach the dishwasher.
  • On the end of the new length of pipe install a 1/2" x 3/8" valve
  • If the hot water line is within 48" you will only need to install a 1/2" x 3/8 compression valve after the tee.

Drain connection

  • Dishwasher fittingHooking up the drain for the dishwasher will require cutting into the fixture outlet pipe (between the sink drain and the trap) and gluing in a dishwasher fitting.
  • Ensure that you place the fitting between the sink and the trap, otherwise sewer gas could enter into the dishwasher. The dishwasher fitting must be installed so that the barbed connection is on the top and aimed in the direction of flow, toward the trap. If installed on the vertical opening, the barbed connection must be aimed upward.
  • Now to cut the pipe. Place the dishwasher fitting on top of the pipe and mark the pipe with a pencil where the pipe will fit into the fitting. Usually the full length of the fitting, minus an inch. Once you are sure it's marked correctly, cut the pipe with a hacksaw/pipe cutters as straight as possible on both of your pencil marks.
  • Dry-fit the dishwasher fitting on the pipe before you glue it, to make sure everything will work. You may need to loosen up or remove the tail piece from the sink in order to squeeze the fitting in.
  • Now glue the fitting onto the pipe in the proper direction. Wipe of the access glue with a cloth/rag.

Note: Normally, the dishwasher fitting comes with the tee end factory plugged. Once you are ready to install the dishwasher drain, cut the last half inch of the barbed part of the fitting, clean the end and join the drainage line from the dishwasher.





Installing the dishwasher

After you have the dishwasher unpacked from the box you'll want to locate the drain outlet and install the 3/8"MPT elbow.

  • Place Teflon tape on the 3/8"MPT elbow and tighten it in with a wrench. Make sure its pointing toward the back when tight.
  • If your drain is going through the floor. Use a tape measure find the distance to the drain under the dishwasher and cut a 1" hole down through the floor using those measurements.
  • If your dishwasher is being installed beside the sink you can drill the drain and water supply holes through the back side of the cupboard as low as possible . Bring your electrical connection to the space near the front right.
  • Dishwasher water supply connectionSlide the dishwasher into place and connect the water braided supply and the drain hose. The drain connection under the dishwasher will likely use a spring loaded clamp but you change it for a hose clamp.
  • Dishwasher electrical connectionsMake the electrical connections, by mating black to black, and white to white, and securing with a wire nuts. The green wire is the ground and must be connected to the metal frame of the dishwasher.

Finishing the installation

  • Connect the braided supply to the valve you installed and the drain hose to the dishwasher fitting (use a hose clamp for good measure).
  • Slowly turn on the water and check for leaks on the elbow(can take a while to leak).
  • Level the feet of the dishwasher and screw the securing clips to the countertop.
  • Turn on the power to the circuit and run the dishwasher again checking for leaks on all the connections.
  • Install the cover plate and offer to do the dishes after supper tonight.