How do you connect PEX to sink?

PEX (cross-linked polyethylene) is a popular type of tubing used for plumbing applications. It is flexible, durable, and easy to install. Connecting PEX tubing to a sink is a straightforward process that can be completed by DIYers with some basic plumbing knowledge and tools.

In this article, we will walk through the complete process of connecting PEX tubing to a sink drain and supply lines. We will cover the required materials, tools, and steps for making secure PEX connections that will withstand the test of time. Whether you are installing a new sink or replacing old galvanized piping, this guide has all the information you need to complete the job like a pro.

Required Materials

Before getting started, you will need to gather the following materials:

• PEX tubing in the appropriate diameter (usually 1/2″ for residential sinks)
• PEX elbow and tee fittings
• PEX crimp rings
• PEX crimping tool
• Sink drain tailpiece with PEX fitting
• Faucet supply tubes or PEX male adapter fittings
• Teflon tape

For the PEX tubing, you will need to determine the required lengths to run from the supply lines to the faucet and from the drain tailpiece to the pipe below. Measure carefully and add a few extra feet to give yourself some slack.

The specific fitting types you’ll need will depend on your sink configuration. Having elbows, tees, adapters, and couplers on hand provides flexibility. You will also need crimp rings to secure the fittings.

A PEX crimping tool is required to compress the crimp rings onto the tubing for a watertight seal. This specialty plumbing tool can be purchased or rented.

Required Tools

In addition to the PEX crimping tool, you will need the following basic tools:

• Pipe cutter
• Utility knife
• Adjustable wrenches
• Hacksaw (to cut metal drain tailpiece if needed)
• Flashlight
• Safety glasses

A pipe cutter will make straight cuts on the PEX tubing. Adjustable wrenches will be needed to tighten fittings. You may need a hacksaw to shorten a metal drain tailpiece. Safety glasses should always be worn.

Before beginning any plumbing project, make sure to turn off the water supply lines. It’s also a good idea to have a bucket and towels on hand to catch any drips.

Step 1 – Cut the Drain Tailpiece

Most sink drain tailpieces are made of PVC or metal. For metal tailpieces, you will need to cut the straight portion to the desired length before attaching the PEX fitting. The cut end should align with the top of the sink drain opening. Deburr the cut edge with a file.

For PVC tailpieces, simply unscrew the slip nut and remove the washer and friction ring. The PEX fitting can then thread directly onto the PVC pipe.

Step 2 – Connect the Drain PEX

Once the tailpiece is prepped, connect the PEX drain line:

1. Slide a PEX crimp ring over the end of the tubing.
2. Push the tubing onto the tailpiece fitting until it sits firmly.
3. Position the crimp ring 1/4″ from the end of the tubing.
4. Use the PEX crimping tool to compress the ring and secure the connection.

Give the drain tubing a gentle tug to verify the crimped connection is tight.

Step 3 – Connect Hot and Cold Supply Lines

Connecting the PEX supply lines is similar to the drain:

1. Slide a crimp ring over the hot and cold PEX tubing.
2. Push the tubing over the supply adapter or faucet tailpiece.
3. Position the crimp ring and use the crimping tool to seal the connection.

The supply tubes may need to be cut to length before crimping. Use a pipe cutter for straight cuts.

Step 4 – Install Shutoff Valves

For convenience, you can install PEX shutoff valves near the water supply lines. These allow you to easily turn off water to the sink for repairs.

1. Cut the supply tubing and insert tee fittings.
2. Add short sections of tubing on each side of the tee.
3. Connect elbow fittings out to the shutoff valves.
4. Use crimp rings to secure all connections.

Installing the valves near the supply lines minimizes tubing runs under the sink.

Step 5 – Connect to Faucet

With the drain and supply lines in place, all that remains is connecting to the faucet:

1. Feed the PEX tubing up through the sink opening.
2. Attach the drain tube to the sink tailpiece.
3. Connect hot and cold supply tubes to the faucet valves.
4. Tighten the PEX connections by hand before crimping.

Keep the tubing as straight as possible for optimal water flow to the faucet.

Step 6 – Flush the Lines and Check for Leaks

Once fully assembled, turn the water back on slowly. Flush both hot and cold lines to remove any debris.

Carefully check all connections for drips and leaks. Tighten fittings as needed. Small leaks may seal themselves as the PEX tubing expands. But larger leaks will require repairs.

If no leaks are present, the installation is complete! Turn the faucet on fully and verify proper water flow and drainage.

Tips for Making Solid PEX Connections

Follow these tips to ensure secure, water-tight connections when working with PEX:

• Cut tubing ends squarely and cleanly to allow proper insertion into fittings.
• Ensure tubing is fully inserted into fittings before crimping.
• Position crimp rings according to manufacturer’s specifications.
• Verify PEX crimp tool is calibrated before use.
• Crimp each connection fully for a tight seal.
• Tug on connections after crimping to check for tightness.
• Use pipe support as needed to avoid stress on fittings.

Taking a careful approach will result in reliable PEX connections that will last the lifetime of the plumbing system.

Conclusion

Connecting PEX tubing to a new or existing sink is a straightforward DIY project. Following the steps outlined above will allow you to make watertight PEX connections that hold up over decades of use.

The flexibility and durability of PEX also makes it easier to maneuver around obstacles under sinks. And the ability to crimp connections without soldering or gluing simplifies installations.

Just be sure to gather the required PEX materials and tools before getting started. Measure twice and cut once. And take time to flush the lines and check for leaks at the end. Paying attention to details will result in professional-quality results.

We hope this guide gives you the knowledge needed to smoothly connect PEX piping to your sink drains and supplies. You’ll gain plumbing skills and have a sink that functions perfectly for years to come.

Frequently Asked Questions

What are the benefits of using PEX for sink plumbing?

PEX offers many advantages over traditional metal or rigid plastic piping:

• Flexible – Easy to maneuver in tight spaces.
• Durable – Withstands freezing, expansion, and corrosion.
• No soldering or gluing – Connections are made with crimp rings.
• Resists scale buildup and chlorine degradation.
• Allows for easy installation of shutoff valves.

What PEX tools do I need?

The main tool needed is a PEX crimping tool to seal crimp ring connections. You’ll also need basic tools like a pipe cutter, wrenches, hacksaw, and utility knife.

What is the easiest way to connect PEX to a sink faucet?

Using a faucet with pre-attached supply hoses that have 3/8″ or 1/2″ male threaded ends will allow quick connections to PEX tubing using female adapter fittings. The fittings crimp right over the PEX.

Can I use PEX for just the hot and cold supply lines?

Yes, you can use PEX for the flexible supply lines and keep the existing metal drain piping in place. This allows you to upgrade the water supply side only.

How do I connect a PEX drain line to the pipes under the sink?

Use a PEX male adapter fitting to transition to the standard pipe diameter below the sink, likely 1 1/2″ or 1 1/4″. Secure the connection with a crimp ring and apply teflon tape to prevent leaks.