Kitchen sinks are a necessary part of any kitchen. They come in a variety of shapes and sizes and can be made from a variety of materials, but the most important thing is having them installed correctly so that they function properly. In this blog post, we’ll walk you through how to install kitchen sink plumbing.

How to install plumbing for kitchen sink fixtures

Kitchen sink plumbing systems consist of drain lines and the water supply. 

Drain lines help clean the sink by draining away used water and other liquids. Meanwhile, water supply lines connect the faucets to a direct water source.

Now that you understand its anatomy, here’s how to install plumbing in a kitchen sink.


Step 1: Gather the required tools, equipment, and materials

The first thing to do is gather all the supplies you’ll need for installation.

You’ll need tools and equipment such as:

  • A tape measure
  • Channel-type pliers
  • A marker
  • A PVC tubing cutter (or a hacksaw)
  • An adjustable wrench

The specifics materials you’ll need include the following:

  • Teflon tape
  • A sink strainer
  • A new drain pipe
  • Plumber’s putty
  • A kitchen drain trap kit

It’s important to ensure you have all the necessary supplies on hand before doing anything, as it will allow you to carry through the installation process without any interruptions. 

The good news is that you can get these tools and materials at any local hardware or plumbing store.


Step 2: Connect the water supply to the sink

In terms of how to install plumbing for a kitchen sink, the next step after gathering your materials is connecting the water supply.

You can do so by first wrapping teflon tape around the threads of water supply lines (both hot and cold). Next, screw the supply lines to the faucets’ respective hot and cold water connections.

Tighten the supply lines using two adjustable wrenches; one holding the nut on the faucet connection and the other tightening the supply line. 

After that, apply the teflon tape around the threads of the water shutoff valves, then connect the water supply lines to the shutoff valves.


Step 3: Assess the drain outlet height

Since kitchen sinks come with different depths, checking the drain outlet’s height is vital before buying a new sink to replace an old one. 

So, start by measuring the trap arm—that is, the horizontal pipe between the branch drainpipe on the wall and the U-shaped trap bend or P-trap. The trap arm always slopes downwards to ensure proper drainage. 

Measure the height between the trap arm’s center to the floor or the cabinet’s base. This will help determine if the sink fits the trap arm for proper drainage.


Step 4: Adjust the drain outlet, if necessary 

If you measure the drain outlet’s height and discover that it’s not low enough to suit the depth of your new sink, you must adjust it. 

You or an expert plumber must then open the wall to adjust the height of the sanitary tee (which connects to the drain pipe inside the wall). Sometimes, you’ll find that you’ll have to cut away the cabinet’s back and wall surface. 

When lowering the drain outlet, you should leave enough space to remove and clean the trap. 

One pro tip to keep in mind is that if you must adjust the drain outlet, it’s ideal to wait until other drain parts are test-fitted before securing or gluing the fittings permanently. This allows room for adjustments.

If the job seems a bit too complicated for you to handle, you may be better off letting a professional plumber do the job.


Step 5: Install the strainer and garbage disposal

Now that you’ve adjusted the drain outlet’s height, you’ll need to remove the old sink and replace it with a new one on the countertop. Also, if you have a double-basin sink, you’ll need to install a sink strainer and garbage disposal. 

So, add the garbage disposal on one side of the sink.

Next, install the sink strainer onto the other sink basin. You can also use this time to install other under-sink components, including a water filter and a hot water dispenser. 

Ensure you work around the fittings appropriately when connecting the drain pipes.


Step 6: Install a drain tailpiece and waste pipe

A drain tailpiece is a short straight pipe that connects the sink strainer to the tee fitting. It has a side outlet that joins the waste pipe from the garbage disposal or second sink basin to the drain trap.

In relation to how to install kitchen sink plumbing, here is how to install the drain tailpiece and waste pipe.

  1. Using a slip nut, temporarily install the tailpiece on the sink strainer, then connect the curved end of the waste pipe to the garbage disposal’s drain outlet.
  2. Allow the straight end of the pipe to extend beyond the vertical tailpiece on the other sink. Ensure the pipeline is slightly sloping downwards towards the tailpiece.
  3. Hold a tee fitting to the waste pipe and tailpiece, then mark the cutting lines on both tubes. Next, cut the pipes on the marked points using a hacksaw or PVC tubing cutter.
  4. Re-install the waste pipe and tailpiece in position, along with the tee fitting, and tighten the slip nuts. However, don’t over-tighten the connections, as that may damage the threads.

One thing to keep in mind is that if you’re installing a sink with a single basin, you don’t need a tee fitting on the tailpiece’s end. Instead, connect the tailpiece directly to the drain trap.


Step 7: Connect the drain trap and check for leaks

The drain trap is made up of a J-shaped trap arm and a U-shaped trap bend. 

The trap bend connects to the bottom of the tailpiece/tee fitting, with the trap arm continuing into the drain outlet on the wall. 

Once the trap arm is assembled, bend and position it below the sink.

Confirm if the trap arm and continuous waste pipe are sloping slightly downward based on the water flow direction, then tighten all the drain connections. 

Next, run water in the two sink basins to check for leaks at the joints. 

Finally, retighten all the joints that leak.


Enlist the help of a professional plumber

Understanding how to install kitchen sink plumbing systems is one thing—carrying it through is another. 

You’ll likely need someone with the right expertise to help you with installation. If you find the process challenging, you can contact an expert plumber from J. Blanton Plumbing to help you. Contact us today!