How To Install Double Kitchen Sink Plumbing with Garbage Disposal

How To Install Double Kitchen Sink Plumbing With Garbage Disposal
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Installing a double kitchen sink with garbage disposal can be a challenging task, but with the right tools and guidance, you can achieve professional results.

In this article, we will walk you through the entire process of how to install double kitchen sink plumbing with garbage disposal.

We will discuss the necessary tools, materials, and steps to complete the installation, as well as some common questions and troubleshooting tips.

How To Install Double Kitchen Sink Plumbing With Garbage Disposal

A double kitchen sink with garbage disposal offers numerous advantages, including increased functionality and improved kitchen hygiene.

However, the installation process can be complex, especially for homeowners with limited plumbing experience.

This detailed guide will provide you with all the information you need to successfully install double kitchen sink plumbing with garbage disposal.

Advantages of Double Kitchen Sinks

Double kitchen sinks offer several benefits over single-bowl sinks, including:

  • Increased functionality: Double sinks allow you to multitask, such as washing dishes in one sink while rinsing vegetables in the other.
  • Improved organization: Separate sinks can help you keep dirty dishes and food preparation areas separate, reducing the risk of cross-contamination.
  • Enhanced kitchen aesthetics: Double sinks can add a touch of elegance and sophistication to your kitchen’s design.

Tools and Materials

Before you begin the installation process, gather the following tools and materials:

  • Wire nuts
  • Garbage disposal unit
  • Hammer
  • Utility knife
  • Needle nose pliers with wire strippers
  • Screwdriver
  • Plumber’s putty
  • Plastic putty knife
  • Non-contact electrical tester
  • PVC pipes and fittings
  • Pipe wrench
  • Hacksaw
  • Teflon tape
  • Dishwasher installation kit (if applicable)

Preparing for Installation

Before you start, clear the area under your sink to create enough space for work.

Turn off the circuit breaker to the garbage disposal unit and use a non-contact electrical tester to ensure no electricity is running through the wires.

Installing the Garbage Disposal

Follow these steps to install your garbage disposal unit:

  1. Remove the old sink drain and clean the area with a plastic putty knife.
  2. Apply plumber’s putty to the flange of the garbage disposal unit and insert it into the sink’s drain hole.
  3. Slide the gasket, backup ring, and mounting ring onto the flange’s open sleeve under the sink.
  4. Snap the mounting ring into place and tighten the screws until the unit is snug against the sink drain.
  5. Remove the dishwasher knockout plug on the disposal unit’s side (if applicable).
  6. Strip the insulation from the black and white wires and connect them to the corresponding wires in the electrical line.
  7. Attach the naked wires to the unit’s green grounding screw and tighten it.
  8. Tuck the wires into the wiring box and close it.
  9. Mount the disposal system onto the mounting ring, ensuring the outlet faces the drainpipe.
  10. Connect the discharge pipe to the disposal outlet and tighten the coupler.
  11. Replace the p-trap and extension pipe, and tighten the hose clamps.

Installing the Double Kitchen Sink Plumbing

To install the plumbing for your double kitchen sink, follow these steps:

  1. Turn off the main water supply to the kitchen.
  2. Place a bucket or towels under the drainage area to catch any water that may spill.
  3. Remove the old supply lines using a pipe wrench or lubricant, if necessary.
  4. Install the new supply lines and tighten them with the wrench.
  5. Dry-fit the PVC pipes and fittings under the sink, cutting them to size with a hacksaw.
  6. Assemble the pipes and fittings, securing them with pipe nuts.
  7. Add a runner washer to the vertical pipe and tighten the nut to create a waterproof seal.
  8. Install the p-trap and wall tube, tightening all connections.
  9. Turn the water supply back on and check for leaks.

Connecting the Dishwasher Drain

If you have a dishwasher, follow these steps to connect its drain to the double kitchen sink plumbing:

  1. Install the dishwasher wye, ensuring the vertical nozzle faces upward and the dishwasher angled nozzle faces the wye.
  2. Connect the wye to the sinking bridge using nuts and washers.
  3. Attach the wye to the other end of the pipe coming from the air gap stem hose nozzle.
  4. Turn on the water supply and check for leaks.

Frequently Asked Questions

Do I need a plumber to install garbage disposal?

While garbage disposal installation typically requires electrical and mechanical connections, a skilled homeowner can complete the task without professional assistance.

Will garbage disposal affect my dishwasher?

Garbage disposals grind food waste into small particles, which can affect dishwasher performance.

Ensure the disposal is clear of food particles before running the dishwasher to avoid clogs and overflows.

Can I run my dishwasher and garbage disposal at the same time?

Since both appliances share the same drain pipe, running them simultaneously may cause plumbing issues.

Clear the garbage disposal of food particles before running the dishwasher.

Troubleshooting Tips

If you encounter issues during the installation process, consider the following troubleshooting tips:

  • Check for leaks at all connections and tighten any loose nuts or fittings.
  • Ensure the garbage disposal unit is securely mounted and its outlet faces the drainpipe.
  • Verify the dishwasher drain hose is properly connected to the air gap and wye.


Installing double kitchen sink plumbing with garbage disposal can be a challenging but rewarding project.

By following the steps outlined in this guide, you can successfully complete the installation and enjoy the benefits of a double kitchen sink and garbage disposal system in your home.

Remember to consult a professional plumber if you encounter any issues or need assistance with the installation process.

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