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DIY Dishwasher Installation: A Complete Guide

Installing a replacement dishwasher yourself is a manageable weekend project if the conditions are right. Here is what you need to know before starting.

Is DIY Installation Feasible for You?

DIY dishwasher installation is genuinely feasible for a straightforward replacement where you are swapping an existing unit for a new one of the same width. If you are comfortable with basic home improvement tasks, have two to three hours to spare, and understand when to stop and call a professional, you can do this yourself and save $100 to $200 in labour costs.

You should hire a professional installer or plumber when:

  • -This is a new installation with no existing plumbing or electrical connections
  • -The existing water supply valve is corroded or cannot be shut off
  • -Your local building code requires a licensed plumber for dishwasher connections
  • -You need to modify cabinetry or add a new electrical circuit
  • -You are not comfortable working under a sink with active water lines

Tools and Materials You Will Need

Before starting, gather everything you need. Having to stop mid-installation to buy a fitting is frustrating and can leave your kitchen without a working dishwasher for longer than necessary.

  • -Adjustable wrench and open-end wrench (typically 5/8 inch and 3/4 inch)
  • -Screwdrivers (Phillips and flat head)
  • -Pliers
  • -Teflon tape (plumber's tape)
  • -Bucket and old towels for water spillage
  • -Flexible stainless steel supply line (if replacing the old one, which is recommended)
  • -Adjustable level
  • -Flashlight or headlamp (working under the sink in poor light is difficult)

Most new dishwashers include a new drain hose. They do not always include a water supply line, which is sold separately. Buy a braided stainless steel 3/8 inch or 1/2 inch compression fitting supply line sized for your installation. A good quality supply line costs $15 to $30 at hardware stores.

Step-by-Step: Removing the Old Dishwasher

Work through these steps in order. Do not rush the preparation steps: a few minutes of careful shut-off work prevents a kitchen flood.

  1. 1.Turn off power to the dishwasher at the circuit breaker. Do not just switch it off at the wall. Verify the circuit is dead with a voltage tester before touching any wiring.
  2. 2.Turn off the hot water supply valve under the sink. This is typically a small oval or lever valve on the hot water pipe. Turn it fully clockwise to close. If it will not turn or feels seized, stop and call a plumber.
  3. 3.Place a towel and bucket under the water supply connection at the bottom of the dishwasher. There will be residual water in the line when you disconnect it.
  4. 4.Disconnect the water supply line from the dishwasher's inlet valve using an adjustable wrench. Expect a small amount of water to drain out.
  5. 5.Disconnect the drain hose from the garbage disposal or sink drain. Have a bucket ready as there will be water in the drain hose.
  6. 6.Open the door and remove the mounting screws at the top of the dishwasher that secure it to the underside of the countertop or to the adjacent cabinets (for stone countertops).
  7. 7.Open the junction box cover at the bottom front of the dishwasher and disconnect the electrical wiring. Note which wires connect where (take a photo) before disconnecting.
  8. 8.Adjust the levelling feet to lower the dishwasher if needed, then slide it out carefully. Dishwashers are heavier than they look. Having a second person helps significantly.

Installing the New Dishwasher: Water Supply Connection

The water supply connection is where most DIY dishwasher installations go wrong. Take your time here.

  1. 1.Locate the inlet valve on the bottom front of the new dishwasher. It typically has a 3/8 inch male threaded fitting. Wrap the threads with 2 to 3 layers of Teflon tape before attaching the supply line.
  2. 2.Thread the supply line onto the inlet valve by hand first, then tighten with a wrench. Do not over-tighten: firm hand-tight plus a quarter turn is sufficient for compression fittings on braided lines. Over-tightening can crack the fitting.
  3. 3.Connect the other end of the supply line to the hot water shut-off valve under the sink. Use the same Teflon tape and tighten firmly but not excessively.

Before sliding the dishwasher into its final position, turn the water supply back on briefly and check both connections for leaks. A small drip at the connection means you need to tighten slightly or re-tape the threads. Address any leaks before proceeding.

Drain and Electrical Connections

Thread the drain hose from the new dishwasher to the garbage disposal or sink drain. The hose must loop high before descending to the connection point, a requirement known as a high loop. This prevents dirty water from siphoning back into the dishwasher. Many installations use a clip under the countertop to hold the hose at its highest point.

Connect the drain hose to the garbage disposal inlet (knock out the plug if this is a first-time disposal connection) or to the drain fitting. Secure with the included hose clamp.

For the electrical connection: match your wire colours exactly to the original setup. Black (hot) to black, white (neutral) to white, bare copper (ground) to bare copper or green. Use the wire nuts provided with the dishwasher and tug each connection after making it to verify it is secure. Replace the junction box cover.

Slide the dishwasher into position, level it (use the adjustable feet), secure the mounting screws, restore power at the breaker, and run a short cycle while watching underneath for any leaks. If everything is dry and the cycle completes normally, the installation is complete.