Dishwasher Pre-installation: What you need to know.

Before I started working in the appliance industry, I thought all dishwashers were the same in terms of size, how they are hooked up, and what’s required with respect to plumbing and electrical for a great installation. Boy was I wrong! After a few years counseling homeowners on products that are best for their needs, I’ve learned that my misconception was a pretty common one to have.

Diagram of Dishwasher

I hope to illustrate for you all of the ins and outs of dishwasher installation, so that when it does come time to replace yours, the entire process from purchasing the dishwasher to installation goes as smoothly as possible.


There are more avenues than ever before to begin your quest for the perfect dishwasher.  You’re reading this online, so you’ve already got a pretty good sense as to some of those resources.  If you’re prone to over-analysis or want to invest as little time as possible in working through and validating the trove of online information, consider connecting with an expert from your local appliance store.  **Shameless plug – if you’re in Seattle, call or text our store at 206-623-8811.  Your appliance expert is trained to ask questions about your budget, use, expectations, kitchen layout, and installation space so that you are far more likely to end up with the perfect product for your specific needs.  Your appliance expert will likely be able to pull in additional considerations that may not have been factored in to your initial review.  You can benefit from their pool of experience in dealing with all different types of uses and installation challenges by getting them involved in your purchase decision.

If you are the type to research your purchases, we do have three blogs that we have published on this topic so far!

To help optimize your online research time, take a moment to prioritize the following:

  • features that you have currently that you wouldn’t want to lose (i.e. heated dry, food chopper, stainless interior, third rack)
  • Space and installation constraints (read the following paragraphs for common pitfalls/additional considerations relating to space)
  • how impactful dishwasher operating noise is in your home
  • price including delivery, installation (including parts), haul away, and any applicable sales taxes
    • this can be absolute, as in, “I will not spend more than $600”
    • this can be relative, as in, “I am willing to spend more to enjoy substantially better machine quality and quieter operation as long as the difference in those benefits are more valuable than the extra money that I am spending for them.”


One thing that most everyone thinks, is that all dishwashers are the same size. While that is mostly true, the cabinet size can vary in both height and width. Chances are that you have the standard 24” wide by 34” tall cabinet. Some common dishwasher spaces are 18” wide.  There are also dishwasher spaces that are slightly shorter measuring at 32” height (what “in the biz” is commonly referred to as “ADA Height” which refers to the height of countertops required in ADA-compliant kitchens.  Always shop with your cabinet measurement in mind.   

One of the most common installation pitfalls that we run into when replacing an old dishwasher with a new one is that the old machine has been blocked in. This happens when the flooring around the dishwasher was replaced (usually during a remodel) and the new flooring was not added under the base of the dishwasher. The height of the new flooring prevents removal of the existing dishwasher.   Our technicians have a few tricks that they can employ to liberate the old dishwasher from that space.  However, you’ll need a shorter-than-standard dishwasher to replace the old dishwasher with as its typically impossible to install a new standard height dishwasher in a space like this.


Knowing where the water inlet valve and drain line connection points are is very helpful in any dishwasher installation.  In the older Metro Seattle area homes that our technicians replace dishwashers in we’ve seen a myriad of ways that water is delivered to and waste water shuttled away from the dishwasher.  Ideally your hookups are mounted underneath the sink and have metal valves which connect to water supply lines that run to the dishwasher. Running a high loop drain that ends in either the sink drain or a garbage disposal, are the most effective for the drain pumps to function properly in dishwashers today.

Another common installation pitfall is when the dishwasher is not directly adjacent to the sink cabinet.  If your dishwasher is “around the corner” in a L-shaped kitchen, or in an island opposite the sink, there is a good chance that additional plumbing work/supplies are going to be needed in order to perform a dishwasher replacement.


We all know that dishwashers are powered, but if you were asked if your dishwasher is plugged in wired directly into your home’s electrical supply, would you immediately know the answer? Most dishwashers today are wire to wire connections but there are some brands, like Asko, that are only going to be plugged into an outlet. That is especially important to know because if you do purchase a new dishwasher that requires an outlet, and you do not have one already, your dishwasher will not be able to be hooked up until a receptacle is installed.

All in all, the more prepared you are, the smoother your dishwasher installation will be. We have created a downloadable PDF (Downloadable below) check list that you can print out to also guide you through the process. Of course, we are always available to help you as well with any and all dishwasher related questions that you might have. Feel free to stop in, give us a call, email us or reach out on social media. Our expert advice is only a call or click away.


  1. Very useful article, really clarified for me the routing of electrical, drainage (especially) and water line/thanks/cp

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