How to plumb a double kitchen sink with disposal and dishwasher in 5 steps

To deal with food waste is a challenge that everyone must face, and having a garbage disposal attached to your kitchen sink is a very simple solution to that challenge. What is not very simple is the process to install your garbage disposal system and connect it to your sink, along with your dishwasher as well. This job typically requires a plumber, which can be quite expensive. You could try doing it yourself, but the consequences of not doing the job properly may be dire. 

However, the job itself is not very difficult at all. That is why we have created this guide on how to plumb a double kitchen sink with disposal and dishwasher. This article will show you the advantages and disadvantages of having a disposal, followed by a step-by-step guide showing you exactly what to do along with the tools you will need to successfully install your garbage disposal and dishwasher to your sink. Good luck, and Happy Cooking!
Check out our previous tip on how to repair single-handle kitchen faucets.

Why you should have a garbage disposal system

Some of you might be thinking of installing garbage disposal with your kitchen sink. A garbage disposal can help you in many ways and can also help to reduce many expenses. In this section of how to plumb a double kitchen sink with disposal and dishwasher, we will cover how a garbage disposal can be helpful and its problems.

A garbage disposal can help you to break down the waste that passes through from the sink drain. The garbage disposal is designed to collect solid food waste in a grinding chamber. When you turn on the disposal, a spinning disc turns rapidly, forcing the food waste against the outer wall of the grinding chamber. This destroys the food into tiny bits, which then get washed by water through holes in the chamber wall. While disposals do have two metal impellers on the impeller plate, they do not have sharp blades.

The advantage of using a garbage disposal is you can install it in virtually most kitchen sinks. It makes cleaning dishes easier by cutting down cleaning time. The garbage disposal also keeps the pipes clear of food scraps. That means no clogged pipes, and thus saving plumber expenses.

The main disadvantages of a  garbage disposal with a sink are the garbage disposal makes a bad odor and if a single component breaks down, the whole disposal needs to be replaced.   

Advantages of having garbage disposal systemDisadvantages of having garbage disposal system
Can be installed with virtually every sink Makes bad odor if not cleared
Hands-free operationsIf one part breaks down, you have to change the entire garbage disposal 
Can help to keep the drainage line clogged free.
Can break-down waste

Why you should install it yourself

First of all, doing things yourself simply feels better. The satisfaction of installing your own machinery, such as a garbage disposal, brings an immense amount of pleasure and self confidence.

Secondly, a skilled plumber is quite expensive. A plumber may charge up to $250 dollars for installation of a garbage disposal. It’s much cheaper and more fun to just do it yourself by following our guide.

Finally, installing your own garbage disposal will give you invaluable knowledge of how a garbage disposal works. Therefore, if you ever have to maintain, repair, or change your garbage disposal in the future, there is no need to call a professional plumber or handyman. You can simply do it yourself, thus saving money on labor costs.

The only barrier to installing your own garbage disposal is the technical challenge. But, that’s why we are here with our detailed guide on how to plumb a double kitchen sink with disposal and dishwasher. Check out the next section for step by step instructions.

How to plumb a double kitchen sink with disposal and dishwasher?

Now that you know how important a garbage disposal is and how installing it yourself can help in many ways, it is now the time for a guided tour of how to plumb a double kitchen sink with disposal and dishwasher on how you can install a garbage disposal with your kitchen skin.  

Types of garbage disposal

There are ⅓  to 1 horsepower garbage disposal in the market. Depending on how frequently you use your kitchen sink and how quickly you want the disposal work, you can select from the models and horsepower from the market. horsepower. If you have a septic system, you’ll need to purchase septic-safe disposal.     

Things and equipment you will need to install a garbage disposal:





Safety Glasses


Prep work

Turn off the water supply lines that are under the kitchen sink. Then remove the water lines. Keep a bucket under the water lines so that the water does not spill around in your kitchen. 

Phase 1

Wire the disposal 

Some disposals come with appliance wires attached while others do not. If your garbage disposal doesn’t have wires, use a screwdriver to remove the cover plate under the disposal and attach the wires according to the manufacturer’s instructions. With most standard disposals you have to connect white wires to white wires and black wires to black wires. After you are finished, screw the cover plate back on.

Phase 2

Now you can install the drain flange and mounting ring. Then roll the plumber’s putty between your hands to form a 1/2-inch thick and 10 inches (25.4 cm) long mold. Apply it to the underside of the drain flange under the sink. Insert the flange into the drain hole and press down equally all the sides to attach it. Then close up the backup ring, fiber gasket, and mounting ring.

To work underneath the sink, you have to use a screwdriver to screw the mounting ring tightly against the sink. This helps to alternate sides, screwing screws, and fix the other screws so that the mounting ring tightens evenly. If you find some of the remaining plumber’s putty squeezed out around the flange, use a knife to trim it away.

Phase 3

Mount the garbage disposal. 

Place the disposal into the mounting ring and make sure that the disposal’s outlet is facing the drain pipe connection. Tighten it until the disposal stays in place.

Phase 4

Now connect the disposal to the P-trap. You have to measure the discharge pipe and use a hacksaw to cut it to size and then attach it to the outlet on the disposal. You must have to be sure to read the manufacturer’s instructions to make sure you connect it properly. Then attach the dishwater discharge tube as well.

Phase 5

After all the hard works, now check the disposal. Turn the power back on, run water into the sink, and turn on the disposal to make sure it works. Then, you have to check underneath to be sure there are not any leaks. Now, run some food through the disposal to be sure it grinds and gets disposed of.

Things you will need to be careful while operating garbage disposal

  1. Always use your disposal with running water. Running water from your kitchen faucet will help move waste into your disposal and down your drain. Without it, garbage can get stuck at your disposal or further down your pipe, which can lead to a clog.
  2. Use only the cold water at your disposal. The cold water will solidify any grease or fat that makes its way down your drain that will help your disposal grind them up and flush them away. On the other hand, hot water causes grease and fat to liquefy which can jam your disposal, and clog your drain.
  3. Don’t overload your disposal as the system can handle a certain amount of load at a time.
  4. In order to avoid buildups and damage to your disposal, you have to make sure that food and waste are fully ground up and flushed out of your unit.
  5. Remove small objects from your sink before use. You have to be careful about the metal spoons and other small metal things.
  6. Avoid grinding waste that will clog or damage your units, like whole bones, grease, liquid fat, uncooked fat trimmings, potato peels, expandable foods (like rice and pasta), and large animal bones

FAQs regarding plumbing a double kitchen sink with disposal and dishwasher

Does a garbage disposal create a bad odor?

If you don’t clean it or flush the disposal regularly, food waste will build up and create unpleasant odors.

Is hot or cold water good for garbage disposal?

Coldwater is better to solidify grease and fat, thus helping the disposal to clean the water drainage. 

Can I install a garbage disposal by myself?

Yes, it is very easy to install a garbage disposal.

How to clean a garbage disposal of your kitchen sink?

Read the article to know how you can clean a garbage disposal. 


How to plumb a double kitchen sink with disposal and dishwasher will help your hero to come out and make sure what you can do without the help of others. This self-reliance will not only boost your confidence; furthermore, will also help you to save a lot of money by retaining you from hiring a plumber. Not only can you install a new garbage disposal with your kitchen sink, but you can also replace it with a new one with the guidance of our how-to plumb a double kitchen sink with disposal and dishwasher. Happy cooking!

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James is a plumber and handyman hailing from the southwest with over 20+ years of experience in his field. He has incredible knowledge on all the brands in the market and how to perform installation, maintenance and repairs of anything you need in the kitchen.

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