Installing a dishwasher requires some plumbing knowledge and may involve electrical work as well. For specific instructions, refer to your manual – they may differ slightly from this general guide.
Switch off both power (at the circuit breaker) and water supply (via the valve under the sink).
Unscrew and lift up the removable panel attached to the front of your dishwasher, then take off any screws that hold it down.
Connecting the Water Supply
If you plan to install a new dishwasher line, switch off both electricity and water supplies at their respective switches (circuit breakers) before proceeding with installing it. Use a wrench to take apart and detach existing hot-water valves from copper tubing beneath sink, before clearing out pipes with cleaner solutions.
Connect the 3/8-inch hose fitting of your dishwasher’s supply tube using a compression connection, and secure each end with a hose clamp. Typically this connects to the sink drain’s inlet; its U-shape prevents backflow into your dishwasher.
If your plumbing doesn’t already feature a dual-outlet valve, installing one will be necessary. Begin by shutting off the kitchen faucet and taking apart its tailpiece; screw a new dual-outlet valve onto the sink’s supply nipple; secure tubing to it by wrapping its threads with pipe wrap tape as you go; finally tighten a compression nut by hand before giving it one final quarter-turn with a wrench to secure.
Connecting the Drain Hose
Before connecting the drain hose, ensure it’s looped over in an arch so the ends do not touch the bottom of the cabinet. Some local codes require this step, while a high loop protects against backflow from sink drains or garbage disposals.
Insert the hose into the dishwasher drain inlet and secure it with a hose clamp. Some models offer dual outlet valves that connect directly to both faucet supply lines and dishwasher drains for easy setup.
Assuming you have your hose, power cord, and supply tube in place, tipping the dishwasher backwards will allow more access to its electrical wiring and plumbing connections. Remove the kickplate, take off the front access panel to expose the junction box, feed three exposed wires through a round hole into it using twist-on wire connectors (or tighten them) then use green grounding wire from appliance cord around a screw in terminal box and tighten.
Connecting the Electrical Components
Your dishwasher’s working parts – such as its water supply, drain hose and electrical connections – are most likely concealed behind an access panel at its base. For easy access, ask someone to help ease it onto its back before opening up its access door and remove it.
Your dishwasher’s water inlet should feature a round, threaded opening with either male or female threading depending on its model. If it doesn’t, you will need to purchase a water line with fittings or adapters as appropriate or wrap the threads with Teflon tape before attaching.
If your dishwasher will be powered via direct wire connection, a terminal box cover and strain relief must be installed to protect its terminals and allow power cord to pass through it safely. Once in place, connect black and white wires together while connecting green grounding wire (if applicable) to terminal box screw or wire nut in terminal box cover or strain relief.
Installing the Dishwasher
Once you have established all electrical and water connections, it’s time to mount the dishwasher. Lay a towel or old blanket down as protection while wrestling it into place; using a level, make sure the dishwasher sits flush with both counters and cabinets and is level enough to drain properly; adjust any legs that may require adjustment with pliers as necessary.
Once connections have been made, take care to reattach the wire connection housing cover before plugging in your power cord.
Richard Trethewey of This Old House plumbing and heating expert shows how to connect a new dishwasher’s water, drain, and electrical lines properly. For best results he suggests purchasing a stainless steel braided supply line designed specifically for dishwashers rather than using one already present in your existing supply chain.