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Prepare and Install New Drain Flange — Install the New Mounting Assembly

Beginner

Part of project

How to Install a Garbage Disposal for the First Time · Step 3 of 7

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In this video

Take a small amount of plumber's putty from its container. Knead it in your hands until it becomes soft and pliable, then roll it into a thin rope about 1/4-inch thick. Apply this putty rope around the underside of the new drain flange. After cleaning the sink's drain hole with a microfiber towel, insert the new drain flange into the hole and press down firmly. From underneath the sink, install the rubber gasket and the large locknut. Tighten the locknut to secure the drain flange, which will cause excess putty to squeeze out around the flange inside the sink. Remove this excess putty and store it back in its container.

Goal: Install the new drain flange securely

  • Using a stain-free plumber's putty is recommended, especially for light-colored porcelain sinks, to prevent discoloration over time.
  • Do not use the hard plastic washer under the flange if using plumber's putty; the putty itself creates the seal.

Used in this video

  • Microfiber towel (Cleaning Cloth Material: Microfiber) — Cleaning the sink drain area before installing the new flange.
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FAQs

What are the essential safety steps to take before and during a first-time garbage disposal installation?

Always turn off the power to the sink area at the circuit breaker first to prevent electrical shock. Wear safety glasses to protect your eyes from debris, and use a bucket and rags to manage water spills. Ensure all electrical connections are secure and properly grounded before restoring power.

Beyond the disposal unit itself, what critical tools and materials are often overlooked but necessary for a smooth installation?

Don't forget plumber's putty for sealing the sink flange, a large bucket and plenty of rags (like HDX Microfiber Rags or WYPALL Towels) for catching residual water, and a good flashlight (like the Panther Vision FLATEYE) to illuminate the workspace. While not always included, you may need a specific InSinkErator 3 ft. Power Cord Installation Kit if your unit isn't pre-wired.

How much time should a beginner set aside for this project, and which part is typically the most challenging?

A first-time garbage disposal installation typically takes 2-4 hours, assuming no major plumbing issues. The most challenging parts are often securing the mounting assembly tightly to the sink to prevent leaks, and making proper, safe electrical connections if you're wiring it yourself rather than just plugging it in.

What are the most common mistakes first-time installers make, and how can I avoid them, especially regarding leaks?

Common mistakes include not applying enough plumber's putty around the sink flange, forgetting to remove the dishwasher knockout plug (if connecting a dishwasher), or not tightening the mounting bolts evenly. To avoid leaks, ensure all connections are hand-tightened and then carefully finished with pliers, and always double-check by running water through the sink for several minutes before buttoning everything up.

Transcript
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to you here i'm using my plumber's putty i'll leave this also in the description down below where i got this so check this out this will definitely help on preventing any types of leaks now this is a clay-like texture i really like this because it is the stain resistant type it doesn't leave any stains in your porcelain what did you need to do is pretty much take out a little bit at a time and just pretty much knead it like dough here i'm just rolling it into a little tiny snake now after you do roll it into a snake or a worm whichever you want to call it i am going to be applying it on the bottom of the drain frame right underneath like i would just see right here now i'm probably not saying the right term sometimes drain frame it's totally up to you for me that's what i call it now i'm putting a pretty thick amount on there just so that i can have enough to cover the whole surface area now after you do that make sure you use the microfiber towel to clean off the perimeter area where you're going to be placing this and you're just going to place it right on the center make sure it's nice and centered and press right under it make sure you do apply a nice amount of pressure and make sure that you take out the excess which pretty much kind of squeezes off the side now don't throw this away this is still good you can pretty much store this back into your plumber's putty container and make sure you cap it off so it doesn't dry out the rest you're just going to clean off with your microfiber towel and continue pressing onto it just in case some excess comes out now you're gonna take another set of plumber's putty and roll it into a worm or a snake and again this step is very important because i did this without it before and it started leaking you're gonna apply that plumber's putty right underneath that drain pipe right on the perimeter underneath as you can see here now this is very important because it will leak if you don't do this and apply the rest of the plastic washer provided and the bolt and make sure you tighten it with your channel lock pliers there's going to be excess while you tighten the nut so make sure you take off that excess you can do it with your fingers and then you can reuse this excess put it back in the plumber's putty container to prevent

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