PEX (cross-linked polyethylene) is a flexible, durable plastic tubing that is commonly used for water supply lines in modern plumbing systems. PEX offers a number of advantages over traditional metal pipes, including resistance to corrosion and freezing, flexibility, and easier installation. However, working with PEX lines requires some specialized knowledge and techniques, especially when it comes to replacing or “stubbing out” fixtures like toilets.
Page Contents
- 1 What does it mean to “stub out” a toilet?
- 2 Step 1: Turn Off the Water Supply
- 3 Step 2: Disconnect the Water Lines
- 4 Step 3: Cut the PEX Lines
- 5 Step 4: Cap Off the Lines
- 6 Step 5: Remove the Toilet
- 7 Step 6: Prepare the Area
- 8 Step 7: Install the New Toilet
- 9 Step 8: Turn the Water Back On
- 10 Conclusion
- 11 Frequently Asked Questions
- 11.1 What tools do I need to stub out a toilet?
- 11.2 How far should I leave the PEX stub outs from the valve?
- 11.3 Can I reuse existing compression fittings when replacing a toilet?
- 11.4 What is the best way to cut PEX tubing?
- 11.5 Should I replace the old angle stop valve when stubbing out a toilet?
- 11.6 Can I stub out a toilet by myself?
- 11.7 How do I cut PEX tubing evenly?
- 11.8 What do I do if my stub outs are too short?
- 11.9 Can I cap PEX lines with regular caps or plugs? No, you need to use end caps specifically designed for PEX tubing. Regular caps won’t seal correctly and could come loose inside the line. How much water will come out when removing the toilet?
- 11.10 Recommended Tools
What does it mean to “stub out” a toilet?
When plumbers refer to “stubbing out” a toilet, they are talking about removing the existing toilet and capping off the water supply lines in preparation for a new toilet installation. This involves cutting the water supply lines, installing stop valves to shut off the water, and capping the lines with short stub outs so they can be easily connected to the new toilet.
Stubbing out a toilet is often required when you are replacing the toilet itself, or during larger bathroom remodels when you need to remove the toilet to access the flooring or plumbing rough-in underneath. Doing this prep work ahead of time makes the new toilet installation much simpler.
Step 1: Turn Off the Water Supply
Before removing the toilet or cutting into any water lines, it’s crucial that you first turn off the water supply to the toilet. Start by shutting off the angle stop valve located under the tank on the wall. This valve controls water flow from the main water supply line to the toilet.
Once the angle stop is closed, flush the toilet to drain any remaining water from the tank and bowl. You want the system to be fully depressurized before proceeding.
Tip
If your toilet has a second water supply line bringing cold water to the tank for flushing (known as a dual flush system), make sure to shut off the valve supplying this line as well.
Step 2: Disconnect the Water Lines
With the water turned off, you can start disconnecting the water supply line or lines from the toilet. PEX lines typically connect to toilets with either push-fit or compression fittings.
For push-fit, you’ll need to depress the release collar on the fitting while pulling the tubing straight out. For compression fittings, loosen the nut and separate the tubing from the fitting.
Take note of the fitting type as you’ll need to match this later for your new toilet. Also inspect the ends of the PEX lines for any signs of damage and cut off any bad sections of tube.
Tools You’ll Need
- Channel lock pliers or tubing cutter
- Utility knife
Step 3: Cut the PEX Lines
Once disconnected, use a tubing cutter to cut both the hot and cold water supply lines a few inches out from the valve fittings. Leaving stub outs that are too long can make it tricky to connect the new toilet, while stubs that are too short may not give you enough room to work.
A good rule of thumb is to leave stub outs that are 3-4 inches long from the valve for standard toilets. For wall-hung toilets, you may want slightly shorter stub outs about 2 inches long.
Tip
Avoid using scissors or wire cutters to cut PEX. Tubing cutters make straight, burr-free cuts that will make leak-free connections.
Step 4: Cap Off the Lines
With the lines cut, it’s important to temporarily cap them off so debris doesn’t get inside. There are a few different options for capping stub outs:
- Push-fit end caps that slide over the PEX tubing
- Compression cap fittings with gaskets
- Plug style caps that insert into the PEX opening
End caps are available at most hardware stores. Insert or attach the caps securely over the cut ends of the supply lines.
Warning
Never use glue or solvent cement products made for rigid plastic pipes on PEX lines. These can damage the tubing and cause leaks.
Step 5: Remove the Toilet
With the water lines disconnected and capped off, you can now remove the existing toilet. Start by detaching the water supply line from the toilet tank and unbolting the toilet from the floor.
Carefully lift the bowl straight up to remove it. You’ll want to place it on cardboard or a towel to avoid cracking the porcelain. Dispose of the old mounting hardware, wax ring, and bolts.
Tip
Have a bucket ready to catch any water left in the toilet trap as you remove it.
Step 6: Prepare the Area
With the old toilet gone, now is a good time to do any needed repairs or updates in the area. Here are some things you may want to address:
- Replace rotted flooring
- Upgrade the water supply valves
- Reroute pipes or lines
- Install new backerboard or wall finishes
Taking care of these issues now will make your new toilet installation go much more smoothly.
Step 7: Install the New Toilet
When you’re ready to install the new toilet, start by dry fitting it to check the positioning. Ensure the stub outs line up with the toilet supply line connections.
Then set the bowl in place on a new wax ring and connect it to the flange bolts in the floor. Thread on washers and nuts to secure the toilet in place.
Next, connect the water supply lines from the stub outs to the toilet fill valve and tank, using compatible fittings. Make sure all connections are tight.
Tip
Have some extra PEX tubing on hand in case your existing stubs are too short to easily connect.
Step 8: Turn the Water Back On
Once everything is attached, slowly turn the angle stops back on and allow the toilet tank to fill. Check for any leaks and tighten any drips or wet connections.
With no leaks, you can fully open both supply valves. Give the toilet a test flush and make any final adjustments to get it functioning properly.
Be sure to attach the toilet seat before using. Then caulk around the base for a clean finish.
Conclusion
Stubbing out an old toilet takes a bit of careful planning and some specialized tools. But this prep work lets you update and replace the toilet much more efficiently when renovating a bathroom.
Following basic PEX plumbing procedures like turning off water, capping lines, and making smooth cuts ensures no leaks or other issues. Before you know it, you’ll have a brand new, modern toilet installed.
Frequently Asked Questions
What tools do I need to stub out a toilet?
The basic tools you’ll need are tubing cutters, adjustable pliers, end caps, utility knife, bucket, and possibly PEX crimp tools or push-fit disconnect clips if replacing any fittings.
How far should I leave the PEX stub outs from the valve?
Leave 3-4 inch long stub outs from the valve fitting to give you enough room to work but still easily connect to the new toilet.
Can I reuse existing compression fittings when replacing a toilet?
Compression fittings can often be reused but you may want to replace them if they are very old or damaged. Always use new gaskets/ferrules when reconnecting.
What is the best way to cut PEX tubing?
Tubing cutters are ideal as they make straight, clean cuts without deforming the tubing. Avoid scissors or wire cutters than can pinch or crush PEX lines.
Should I replace the old angle stop valve when stubbing out a toilet?
It’s a good idea to install new 1/4 turn angle stop valves when stubbing out to prevent leaks and ensure optimal water flow.
Can I stub out a toilet by myself?
While not overly complicated, removing and stubbing out a toilet involves shutting off main water lines which is best done with a helper. But an experienced DIYer can potentially do it alone.
How do I cut PEX tubing evenly?
Use a tubing cutter and make sure the tubing is straight in the cutter. Spin the cutter around the tube to score it evenly until it cuts through.
What do I do if my stub outs are too short?
You can use PEX couplers and additional tubing to extend stub outs that end up being cut too short. This allows you to “build out” the stubs as needed.