Plumbing a Kitchen Double Sink with Dishwasher and Disposal

How to plumb a kitchen sink

Double kitchen sink plumbing is basically the installation of a double basin sink in your kitchen. Unlike single sink plumbing, the installation of a double kitchen sink is significantly more difficult than single sink plumbing.

Despite the convenience that the double sink offers, its installation is not as easy especially if you do not have any plumbing experience.

However, you should not get worried because we will help you every step of the way to get your plumbing running in a few.

How to Plumb a Kitchen Double Sink

Double kitchen sinks are a dream for every home’s kitchen. Double kitchen sink plumbing can cause problems sometimes.

You can either get help from a professional plumber if you need to install a double sink or buy all the required equipment and follow the following steps to install it yourself.


First, you need to ensure that you buy the right kit for your drain. You should purchase kits that resemble how your drain is set up.

The pattern can be central and the drains can also be located at opposite ends of the sink. Specific drainage systems may also be needed.

The second sink in this case can serve as the waste disposing unit. The supply lines you purchase should match the ones that are in your drains.

After purchasing the kits take them home and lay the pieces out. note where the pieces join together to make work easy for you when fitting the pieces below the sink.

Installing the supply lines.

To install the supply lines, you will need to turn off the main water supplies to your kitchen. Less or no water in the system will make the installation easier.

To catch any water that may be flowing through the system, you can place a pot or a bucket beneath the drainage area or layout some tea towels.

Remove your old supply lines using the wrench or some lubrication if you experience any problem. Using the wrench, install the new supply lines to replace the old ones.

Installation of plumbing.

Now it’s time to install your pipes. After dry-fitting your pieces together use a hacksaw to cut them to fit the area beneath your sinks. layout the P trap, PVC pipes, and the wall tube.

After fitting the pipes and the pieces below the sink, into the piping slide the nuts of the pipe. On top of the vertical pipe add a washer.

Tighten the nut to ensure that the pipe is watertight and join the two pieces of the pipe together. On top of the pipes lay the P trap and push up to the sink.

The wall-tube should be threaded into the correct position and all the bolts that hold the pipes on the sink at the beginning of the water outlet should be tightened. You can now turn your water on.

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

Tools needed in this include:

  • Dishwasher installing kit.
  • 2 compression clamps.
  • A dishwasher wye.
  • Two rubber washers.
  • Pliers.

For murky water that is left on the dishwasher to drain and leave you with a clean dishwasher, a disposal system is needed. Many people believe that plumbing a kitchen double sink with disposal and dishwasher is hard. It is not, the following process proves so:

Turning the water source off

This prevents over flooding of water on the kitchen sink.

Drilling a hole

On the double sink kitchen use a drill to make a hole. Measure the diameter of the hole because the air gap stem should fit into it.

Installing the air gap

Pass the air gap with a rubber washer on top of it through the hole made in the sink kitchen. On the air gap system place the 2nd rubber washer to ensure that the air gap remains watertight and airtight.

To ensure that the air gap remains tight as you fasten the compressor nuts hold the stem with one hand. Tighten the compression nut under the sink using the wrench as you firmly hold the air stem using pliers.

Installing the disposal pipe

The dishwasher disposal pipe should be passed through the small air gap system that has been set up. For this, you will require compression nuts or a quality water hose clamp.

Make sure that the nuts and the clamps are tightened. The disposal pipe should be also in a tiptop state to ensure that murky water will reach the air stem every time.

Connecting the air gap and the double kitchen sink

Measure the distance between the 2nd outlet of the air gap stem and the kitchen sink drain pipe.

To achieve flexibility, use a larger disposal hose than the measurement. Cut the disposal pipe to the fitting size and attach one end of the tube to the 2nd outlet of the air system.

Adding a dishwasher wye

Measure the length of the wye. Cut the pipe that will connect accordingly. To set up the why correctly make sure that the inlet pipe is upwards and is facing the dishwasher towards the war.

Using nuts connect the why to the sinking bridge and use washers to ensure the connection is watertight.

Adding the wye with the drain pipe

Attach the wye to the ordain pipe’s other part that comes out of the air stem inlet.

Turn on the water supply

Your double kitchen sink with disposal and dishwasher is complete once you attach the drainpipe with the wye. Turn on the water and check if everything you have done is working.

How to plumb a kitchen double sink with the garbage disposal?

The following tools are required for the process.

  • Screwdriver.
  • Hacksaw.
  • Hex wrench.
  • Hammer plies.

The following is the process of installing a kitchen sink with garbage disposal:

  1. Assemble the parts that the disposal comes with and ensure that they fit perfectly before you begin the installation process.
  2. On the flange apply a suitable plumber putty. Gently press it until it falls into place. To prevent it from moving, set the disposal on the collar.
  3. Slide the disposal on to the underside of the collar once stack the backup flange, the mounting ring, and the fiber gasket. Install the snap ring and don’t forget to tighten the screws too once the disposal is in place. Clean the putty that is excess as well.
  4. To access the electrical cord, remove the wire cover plate and connect it correctly by matching the colors of the wires. Once you are done reattach the plate.
  5. Remove the drain plug using a hammer.
  6. In the discharge outlet, insert the gasket gently and attach the discharge tube with a flange and bolt to connect the drain. Align the mounting ring with the three tabs to hang the garbage disposal. The ridges should then be locked to the tab using the wrench.
  7. Connect the dishwasher drain. Before connecting the drain pipes you should make sure that the discharged pile is aligned correctly.

How to plumb a single bowl kitchen sink with disposal?

Adding garbage disposal in a single bowl kitchen sink is much easier than adding one in double sinks.

The tools needed include:

  1. Wire nuts.
  2. A disposal unit.
  3. Hammer.
  4. Utility knife.
  5. Plumbers putty.
  6. Wire strippers.
  7. Screwdriver.
  8. Plastic putty knife.
  9. Pliers.
  10. Non-contact electrical tester.

The steps of the installation are as follows:

  • To have enough space for work clear the cupboard beneath your sink.
  • for disposal of the unit’s wiring, switch off the circuit breaker.
  • Make sure that the electricity is not running through the wires for the disposal under the kitchen sink using a non-contact electric tester.
  • Undo the couplers using the pliers and attach the P-trap with the drain extension pipe to the underbelly of the sink. Use a rag to plug the drain line to prevent odors coming out from distracting you.
  • Separate the drain flange from the bottom of the sink by unscrewing the nut under the drain coupling using the pliers.
  • Scrap the putty of the old plumber off the drain hole using a plastic putty knife.
  • Around the flange of the garbage disposal unit rub some putty around. Into the bottom hole of the sink insert the flange and then to the flange open sleeve which is under the sink, move the gasket and the backup ring.
  • The mounting ring should then be attached and snapped on. The screws should be tightened until the unit fits well against the sink drain.
  • Make sure your wipe the excess plumber’s putty.
  • Ensure that you push out the dishwasher knockout plug that is on the disposal unit’s side. If you don’t have a dishwasher leave the plug in place.
  • Remove the cover of the disposal unit wiring compartment and take six inches of the electrical cable from the wall switch. Once you insert the cable into the wire clamp in the wiring compartment, tighten the clump using a screwdriver.
  • Inside the wiring compartment, unseat the six inches of the cable using the utility knife. Remove half and inch insulation from the black and white wires using the wire strippers.
  • Attach the black cable wire to the black wire and the white cable wire to the white wire using the wire nuts. Tighten the unit after wrapping the bare wires around the unit’s green grounding screw.
  • Close the wiring compartment after tucking all the wires into it.
  • After placing the disposal system on the mounting ring, make sure the outlet faces the drainpipe by turning the unit.
  • Before tightening the coupler make sure the disposal discharge is placed inside the disposal outlet.
  • Before returning the p-trap and the extension pipe, take out the rag you had put in the drain line. Use the pliers to tighten the couplers.
  • If you have a dishwasher, its drain line should be connected to the dishwasher knockout and the coupler tightened.
  • Open the faucet over your sink after turning back on the circuit breakers. To see if you did a good job switch on the disposal unit. If there are no signs of water leakage your disposal has been set up perfectly and it is ready for use.