Most residential dishwashers have the same hook up for the dishwasher drain and the water supply. The standard dishwasher drain hose size is 5/8"(I.D.) inside diameter on both ends. The drain,electric, and water connections are all located on the bottom of the dishwasher. It is Recommended by the manufactures that you install the dishwasher water supply line to the hot water supply, but it can be connected to the cold water supply to save on energy cost. The water supply line for a dishwasher will have a 3/8" compression connection on both ends.
The dishwasher drain gets connected to either the garbage disposer(if you have one) or gets connected to a "dishwasher tee". A dishwasher tee gets installed between the tail piece and the trap and creates the connection for the dishwasher drain.
When determining the correct length needed for the water supply line, the electric connection,and for the drain connection to the dishwasher make sure you add a extra 4' to the measurement. If you are using a dishwasher cord for the electric supply instead of hardwiring the electric straight to the dishwasher there is no need to add the 4' for the electric connection cause you can easily unplug the dishwasher cord. To determine the length needed for the water supply line, drain line and/or the electric wire(for hard wiring direct) you would add 4' to the measurement from the shut off valve to the center of the opening for the dishwasher. the reason you need to add the extra 4' to the measurement is so the dishwasher can be pulled out of the cabinets to be repaired/replaced.
In some areas your local building codes require you to install a dishwasher air-gap between the dishwasher and where it connects to either the garbage disposer or to a dishwasher tee. Air-gaps prevent the back-flow of drain water through the dishwasher drain hose into your drinking water, and the air-gap forms a trap like effect to block the smell from the sewer(same effect as a trap under the sink) gases.
Dishwasher air-gaps are recommended to be installed on the sink where the main body of the relief drain for the air-gap is above the sink, close to the faucet is the recommended location cause if the plumbing drain line backs up the air gap will divert the water out into the sink blocking the passage to the dishwasher. If you install a dishwasher air-gap where the main body is under the sink, and the plumbing system backs up the water would be diverted under the sink on to the cabinets and possibly onto the floor.
But if your local building codes do not require a air-gap to be installed for the dishwasher drain, you can use the standard method people used before air-gaps... A simple loop in the drain line to block the sewer gases.
For the connection under the kitchen sink to the water supply line for the dishwasher, the sink should have a existing single outlet water shut off valve connecting the water supply line to the faucet. But they only have 1 outlet to hook up to. The easiest way to adapt a single oulet shut off valve for a dishwasher to the hot or cold line is to remove one of the existing shut off valves and install a double outlet shut off valve.
The double shut off valve has two 3/8" compression oulet connections allowing you to hook up two water lines on one shut off valve. You can get a double valve for either a threaded connection to the pipe or for a compression connection to the pipe.
You will also need a dishwasher elbow to connect the water supply line to the dishwasher. A dishwasher elbow is simply a brass fitting with 1/2" male threads adapting to a 3/8" compression connection on the other end of the elbow. I recommend using a braided water supply line, they are easy to install and although they dont last as long as copper they will still most likely out last the dishwasher.
Installing A Dishwasher Drain
Step1.Using a 1 wood drill bit, drill the first hole one inch off the back of the cabinet and two inches above where the dishwasher drain connects to the sink drain(or garbage disposer). If you are going through more than 1 cabinet to get to the dishwasher, go ahead and drill a hole in the same location through as many cabinets as needed.
Step2. Drill another hole(or holes depending on how many cabinets) above or beside your first hole for the water supply.
Step3. (If the dishwasher tee is already installed or your connecting to the garbage disposal skip to step 6) If you have not installed the dishwasher tee onto the sink drain, place a small bucket or bowl under the trap and remove the trap.
Step4. Install the dishwasher tee between the bottom of the kitchen sink tail piece and the trap.
Step5. Reinstall the trap.
Step5. Wrap thred-tape around the female end of the dishwasher elbow and install the dishwasher elbow into the water inlet valve located on the bottom of the dishwasher.
Step6. Connect the drain hose to the dishwasher using a hose- clamp.
Step7. Install the water supply line to the dishwasher elbow.
Step8. Connect the electric to the dishwasher. Wiring For A Dishwasher
Step9. Run the water supply and the drain hose over to under the sink through the holes you drilled.
Step10. Being carefull not to pinch the water supply or the drain hose slide the dishwasher back into the cabinet.
Step11. Connect the drain hose and the water supply to there relative connections under the sink.
Step 12.Turn on the water and check to see that the dishwasher works and check for water leaks, if every things ok wait about 20 minutes and check for leaks again some times a slow leak will take awhile to show. Still no leaks go ahead and mount the dishwasher to the counter top.
If you have a question about installing a dishwasher drain or a question about another repair post it in the user feedback.
