How To Plumb A Kitchen Sink With Disposal And Dishwasher

How To Plumb A Kitchen Sink With Disposal And Dishwasher
  • Author: Amanda Arnold
  • Posted On: January 19, 2022
  • Updated On: September 29, 2023

Let’s face it, no matter how old you are, picking up food leftovers by hand is an unpleasant experience. Plumbing a sink correctly is critical for proper disposal. Therefore if you are thinking about how to clean food disposal property, you can do so by installing a garbage disposal and dishwasher. Efficient, right? 

You can learn to plumb a kitchen sink with disposal and dishwater with the help of the steps discussed below. You will also learn about the cost, and benefits of adding disposal and dishwasher into the mix. 

Why Do You Need To Install The Disposal System

You do not require an entire kitchen remodeling to install a proper disposal system with the kitchen sink. One of the most common features in modern kitchens is garbage disposal beneath the sink. So in case to fix a leaky kitchen sink faucet or replace the kitchen sink, homeowners opt to install a disposal system as well, if not in place already. 

  • Break Food Remanant: A garbage disposal can break up any food remnants that wind up in your sink and drain. 
  • Fast Cleaning and No Blockage: You will not only be able to complete your dishes faster, but you will also have less blockage. This is also a great thing to have if you care about being environmentally friendly.
  • Easy Disposal: If you can break up more food waste and flush it down the sink, it will be more easily disposed of through sewage, minimizing the amount of rubbish that ends up in landfills.

In addition, the more food you can put in your garbage disposal, the less food you will waste. That means attracting fewer mice and vermin to your residence in urban locations. Furthermore, in suburban areas, you won’t have to worry about wildlife being attracted to the smell of food waste and digging through your trash. If it keeps happening you need to remove kitchen faucet along with the sink and install a new one. 

Steps To Install A Sink With Disposal

Steps To Install A Sink With Disposal

You’ll be relieved to learn that a dishwasher and garbage disposal may both be installed under a single kitchen sink. So, it won’t be too difficult with the double kitchen sink. Measure the size of the dishwasher and dispose of the space available under the sink. If it fits correctly, you can begin the installation process.

Collect Plumbing Tools  

Start by collecting the right plumbing tools to get the job done. You will need the following. 

  • Wrench
  • Hammer pliers
  • Hacksaw
  • Electric drill
  • Screwdriver

 Remove The Previous Sink Pipe

The sink pipe drains your wastewater. You will need to replace kitchen sink drain. The P-trap is the name given to it by most plumbers. You’ll need to locate the tailpiece to remove this old sink pipe. Remove it from the wall drain by rotating it counterclockwise.

You’ll need a pipe wrench if you’re dealing with metal pipes. If you have a strong hand, you can easily remove the plastic. All nuts were loosened, and the pipe was disconnected from any additional connections. 

 Use A Suitable Plumber Putty

Apply the appropriate plumber putty on the flange and gently press it into place. To keep the disposal from moving, place it on the collar. Stack the backup flange, fiber gasket, and mounting ring on the bottom of the collar, then carefully slip it on.

Install the snap ring after it’s in position, then tighten the screws. Remember to clean up any extra putty.

 Fit The Trapes Appropriately

All of the P-traps must be correctly positioned in their respective holes. You’ll have to trim them into the appropriate shape for this. Measure the diameter of the wye and cut it to fit appropriately within the wall drain. Otherwise, you can face plumbing problems causing mold. 

The trap will be linked to the sink on one end and the wye on the other. They’ll both wind up in your dishwasher and garbage disposal devices. Make sure you measure everything before cutting; otherwise, it may not fit properly, requiring additional effort.

 Install The Pipes

Previous putty and residue will be present. You’ll have to remove them and replace them with new putty. After that, place all of the pipes and flange for your dishwasher and disposal in the correct holes.

Reassemble the system by replacing the mounting ring and tightening all the nuts. 

 Check Before Start Using

Instead of speculating, make sure you do some tests before using it. Start the dishwasher and garbage disposal, and look for any leaks. To function effectively, the bend of the p-traps must also be on the right track.

If everything appears to be in working order, you are finished with your plumbing.

How to Plumb a Kitchen Sink with Garbage Disposal without Air Gap 

How to Plumb a Kitchen Sink

It is far easier to install a disposal pipe without installing the air gap. Most of the installation steps are the same. However, you will need to make certain adjustments during the installation process if the kitchen sink isn’t leveled. 

Some homeowners prefer to plumb kitchen sink with garbage disposal without an air gap. The airtight gap between the disposal connection and the dishwasher is connected to the ground level. You do not need any extra set of tools for this step. 

All you need to do is connect the sink and form a loop. You can use nuts to provide better support and attach them on either end. After that, you will enjoy washing and cleaning your dishes without clogging the kitchen sink drain. 

How to Install Dishwasher to Garbage Disposal 

How to Install Dishwasher to Garbage Disposal 

Once a dishwasher has cleaned the dishes, the used water needs to drain into the drainage system. With no proper drainage system, the dirty water will remain in the dishwasher hence making the dishes dirtier after cleaning. To make the dishwasher work more efficiently you to channel dirty water in drainage properly. 

So, after installing the garbage disposal, you will be required to follow these steps to connect it to the dishwasher. 

Step 1

Similar to the previous step discussed, to install the dishwasher, you need to cut off the water supply to ensure there’s no water leakage. 

Step 2

With the help of a screwdriver and a light hammer, remove the knockout plug. Also, you will need to use a needle nose plier to remove the plug from the nozzle. 

Step 3

Gently insert a threaded stem from the air gap fitting’s top into the sink’s hole at the back. The included runner washer should be inserted into the stem’s upper side before being tightened into the trim cap. Please refrain from tightening the cap with pliers or a wrench. Use your hands instead.

Step 4

Turn the air gap fitting slowly by hand so that the angled nozzle faces the garbage disposal.

Step 5

Fit the hose clamps provided on the other end of the garbage disposal drain hose after carefully pushing one side of the hose onto the dishwasher’s nozzle. The lower clamp should be gently inserted into the hose (at the nozzle) and then tightened with a screwdriver.

Step 6

Cut the upper side of the hose to a suitable length using your utility knife. Make sure it does not bend and fits the air gap nozzle precisely.

Step 7

On the opposite side of the dishwasher drain pipe, install a one-inch hose clamp. Make careful to cut the hose to a length that will fit snugly around the vertical nozzle without a loop or bend. Use a hose clamp to tighten the end after inserting it vertically.

Say Goodbye to Food Waste!

Once the garbage disposal is installed, connecting the dishwasher outlet to your home’s drainage will be much easier since the garbage disposal has a special outlet for dishwashers.

It’s simple to connect your garbage disposal and dishwasher to your kitchen sink. All you have to do now is follow the basic and uncomplicated steps outlined above. Read the manufacturer’s instructions before beginning the installation process and follow them later.


  • How To Avoid The Disposal Waste Being Backed Up Into The Dishwasher?
    If your garbage disposal becomes clogged, the water may begin to flow in the reverse direction, ending up in your dishwasher. It’s as simple as pouring boiling water down the garbage disposal drain once a week.
  • How Much Garbage Disposal and Dishwasher Installation Costs?
    How Much Garbage Disposal and Dishwasher Installation Costs? The average cost of a garbage disposal unit is between $85 - $200 while dishwashers can cost around $250 - $3,500. Professional installation can increase the charges between $100 - $450.
  • How Long Does it Take to Install Garbage Disposal and Dishwasher?
    It all depends on the experience you have in home improvement and plumbing issues. You will also need to consider the kitchen sink’s compatibility with the units you are planning to install. However, a professional plumber may take 1 hour - 4 hours to install it.
Avatar photo
Author: Amanda Arnold

Amanda has been working with ConstructionHow since 2021. Her experience spans over 5 years in the creative niche such as home decor and trends, landscaping, renovations, and custom architectural values. As a home designer expert, she has a keen eye for the latest home improvement trends with accurate facts that readers find impossible to ignore. Being invested in home-building trends is how she has gained her lucrative expertise exploring more to bring a positive ambiance for all homeowners (and even tenants!). Currently, she lives in a beautiful beach home, a source of fascination for her.