How to Use PEX Tubing for Kitchen & Bathroom Water Supply
- Isaac Ostrom
- 4 days ago
- 7 min read
Hey guys, welcome back to the Tile Coach blog! I’m Isaac, and today we’re diving into one of my favorite plumbing upgrades — using PEX tubing for kitchen and bathroom water supplies.
If you’ve been around my channel or job sites, you’ve probably seen me using PEX more and more lately. It’s lightweight, it’s flexible, and it’s pretty much taking over the modern plumbing game. I’m going to walk you through exactly how to connect PEX to copper, show you the different adapters and fittings, and break down some tools you’ll want to have in your kit.
Whether you’re a DIYer doing your first remodel or a pro looking to streamline installs, this post will show you why PEX is such a game-changer for water supply lines.
Key Takeaways for Homeowners & Pros [TL;DR]
PEX tubing is easier, faster, and cleaner to install than copper.
You can connect PEX directly to copper using brass adapters or SharkBite push fittings—no soldering required.
The expansion tool makes tight, watertight seals without clamps or glue.
PEX is perfect for remodels, retrofits, and tight spaces like under sinks or behind walls.
Once you try PEX, you’ll probably never go back to soldering copper full-time.
Tools and Materials You’ll Need
Here’s what I used in the video (and what I keep on every plumbing job):
PEX Tubing (½” and ¾” are most common)
PEX Expansion Tool (around $350, includes 2 batteries)
Expansion Rings
Copper-to-PEX Adapters (male and female)
Couplers, Elbows, Stub-Outs
Push Fittings (SharkBite) – optional for no-solder installs
Pipe Cutter – always use a clean, square cut
Marker & Tape Measure
What Is PEX Tubing?
If you’re new to PEX, here’s the quick rundown. PEX stands for cross-linked polyethylene, and it’s a flexible plastic pipe that’s slowly replacing copper in modern plumbing systems.
Why? Because it’s easy to work with, doesn’t corrode, and can handle hot and cold water lines up to about 200°F. It’s the go-to material for kitchen and bathroom remodels, and it makes retrofits a whole lot simpler.
Unlike copper, you don’t need a torch, flux, or solder. You’re just using fittings, expansion rings, and a little bit of know-how.
Advantages of PEX Over Copper
Let’s be honest — soldering copper is an art form. It takes time, it takes skill, and it can be messy if you’re in a tight space.
Here’s where PEX wins:
Flexibility: You can bend and route it around obstacles — no more cutting 90° elbows for every turn.
Speed: Expansion fittings and push-fit systems go together in seconds.
No Flame Required: Perfect for remodels where open flame isn’t safe.
Cost Savings: PEX tubing and fittings are cheaper than copper.
Corrosion Resistance: Won’t pit or scale from minerals in the water.
It’s not that copper doesn’t have its place — but for most residential jobs, PEX just makes sense.
The Essential PEX Fittings You’ll Use
Let’s go through some of the common fittings I showed in the video (timestamp 1:10–2:45):
🔩 Copper-to-PEX Adapters
These are your bread and butter when connecting copper to PEX. They come in male and female threaded styles:
Male Adapter: Screws into a threaded valve or fixture.
Female Adapter: Threads onto a male fitting.
Both types are made of brass — and if you’re like me, you probably appreciate that “gold look.” Brass fittings are tough, corrosion-resistant, and reliable.
You’ll also find two connection styles:
One that slides over the copper pipe.
One that slides into the copper fitting (like a sweat valve or 90° elbow).
Knowing which one to use depends on your setup.
🚰 Stub-Outs
Stub-outs are short sections of copper or PEX that come out of the wall for your toilet or sink angle stops. You’ll solder or connect the stub-out to PEX inside the wall and attach your shutoff valve on the exposed end.
🔄 Couplers & Elbows
You’ll find these in PEX just like in copper — couplers join two sections of pipe, and elbows change direction. I usually use 90° elbows in bathrooms and kitchens where tight bends are needed.
How to Use the Expansion Tool (Timestamp 2:45–4:00)
This is where the magic happens. The PEX expansion tool is what makes the system so solid. It stretches the end of the tubing just enough for a fitting to slide in — then the tubing shrinks back down, gripping the fitting tight.
Here’s how it goes step-by-step:
Cut the PEX cleanly with a pipe cutter.
Slide an expansion ring over the end of the tubing. (It can only go one way — there’s a built-in stop so you can’t mess it up.)
Use the expansion tool to open up the end of the tubing.
Insert your fitting all the way to the stop.
Wait a few seconds for it to shrink back — that’s it! You’ve got a watertight seal that’ll hold up under pressure.
You don’t need glue, solder, or clamps. Just that expansion and a clean fitting.
If you’re doing a bunch of installs, investing in a cordless expansion tool is worth it. The one I use runs about $350 and comes with two batteries — it’s solid, and it’ll last for years.
Using Push-Fit (SharkBite) Fittings
If you don’t want to invest in the expansion setup right away, SharkBite fittings are a great option.
At 4:40 in the video, I show exactly how these work: Just push the PEX or copper pipe into the fitting until it clicks. Inside, there’s an O-ring that creates a watertight seal. That’s it — no solder, no tools, no leaks.
These are especially handy for small repairs, quick installs, or spots where you can’t get your expansion tool in.
Connecting PEX to Copper (Step-by-Step)
Here’s a breakdown of the whole process like I showed on-site:
1️⃣ Prep the Copper
Cut your copper pipe clean with a pipe cutter and make sure the edge is deburred. Wipe it down so you’re not sealing dirt or corrosion inside.
2️⃣ Choose the Right Adapter
Decide whether you’re going into a copper fitting or over a copper pipe.
For copper-to-PEX inside, use a slip fitting.
For copper-to-PEX outside, use an over-fitting adapter.
3️⃣ Attach the Adapter
You can solder it in place if you’re comfortable with a torch. If not, this is where SharkBite fittings shine — just push it on.
4️⃣ Connect the PEX
Once your copper adapter is in, expand your PEX, slip it on the fitting, and let it contract. That’s your connection — watertight and ready for pressure.
Practical Applications
You can use PEX just about anywhere you’d use copper:
Kitchen Supply Lines – Great for sinks, dishwashers, and fridge water lines.
Bathroom Plumbing – Perfect for vanities, shower valves, and toilets.
Remodels & Retrofits – Snakes through walls and floors easily.
Repairs – Ideal for replacing old copper sections.
PEX makes routing lines through tight spaces super easy. I love it for remodels because it bends where copper can’t.
And when you’re working under a vanity or inside a wall cavity, not having to solder is a big win.
Tips for Working with PEX
Here are a few best practices I’ve picked up over the years:
Always use a sharp PEX cutter for clean, square cuts.
Mark your depth before inserting fittings — ensures a full seal.
Make sure your expansion rings are seated correctly.
Use brass fittings for longevity and higher pressure resistance.
Keep your PEX tool maintained — clean and oil it once in a while.
When using SharkBite fittings, make sure the pipe is fully inserted.
Do it right the first time and you’ll have leak-free installs that’ll last decades.
Why PEX Is Perfect for Modern Plumbing
PEX has completely changed how we run water supply lines. It’s:
Durable – Handles temperature changes without cracking.
Versatile – Works with push-fit, expansion, or crimp systems.
Efficient – Cuts install times in half.
Reliable – Lasts 25–40 years with proper care.
For pros, that means faster installs and fewer callbacks. For homeowners, it means reliable plumbing without worrying about corrosion or leaks.
Why Plumbing Is an Awesome Trade (Timestamp 5:30–6:00)
Before wrapping up, I want to throw something out there — plumbing and the trades in general are awesome careers.
You get to work with your hands, solve problems, and actually create something tangible that improves people’s lives. Every job you do helps someone — and that’s a great feeling.
Whether you’re young and just starting out or you’ve been thinking about switching careers, learning skills like this can open a ton of doors. You’ll make friends, you’ll make good money, and you’ll never stop learning.
Frequently Asked Questions (FAQ)
Q. Is PEX tubing suitable for hot water lines?
Yes. Most PEX tubing is rated up to 200°F, perfect for both hot and cold applications.
Q. Can I use PEX outdoors?
Not directly — PEX isn’t UV resistant. If you have to run it outside, protect it with insulation or conduit.
Q. How long does PEX last?
Usually 25–40 years with proper installation and maintenance.
Q. Do I need special tools to install PEX?
For expansion systems, yes — you’ll need an expansion tool. For push-fit systems, no tools are required.
Q. Can I connect PEX directly to copper pipes?
Absolutely. Use brass PEX-to-copper adapters or SharkBite push fittings for quick transitions.
Final Thoughts
If you’re planning a kitchen or bathroom remodel, PEX tubing is hands-down one of the smartest upgrades you can make. It’s clean, fast, flexible, and just plain fun to install.
Whether you’re soldering copper adapters, expanding rings, or pushing SharkBites together, the process is super beginner-friendly.
Once you try PEX, you’ll see why plumbers everywhere are switching. It’s reliable, durable, and saves tons of time — all without compromising quality.
So grab your expansion tool, some fittings, and give it a shot. Plumbing doesn’t have to be intimidating — it’s just another craft you can learn, one connection at a time.
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