How to Connect PEX to Copper Pipe

Knowing how to connect PEX to copper is essential for almost any modern plumbing repair, because most American homes now contain both materials. Copper has been the standard for decades, while PEX (cross-linked polyethylene) has become the go-to for new work and remodels thanks to its flexibility and low cost. Sooner or later, a PEX run has to meet an existing copper line — and there are four proven ways to make that connection, ranging from a tool-free push-fit to a soldered adapter. This guide compares all four and walks you through the easiest one step by step.

Why Connect PEX to Copper?

Most PEX-to-copper connections happen during a repair or a partial repipe. A homeowner might replace a leaking copper section with PEX, add a new bathroom fed by PEX off an existing copper main, or connect a new PEX manifold to the copper water service entering the house. In each case, the transition fitting is the bridge between the old system and the new one.

PEX and copper cannot be joined directly — there is no glue or solder that bonds plastic to metal. Every connection uses a transition fitting with a copper or brass end on one side and a PEX barb or push-fit end on the other. The fitting does the work of sealing to both materials, each in the way that material requires. That is why the choice is really about which transition fitting to use, not about joining the two pipes themselves.

Both materials are approved for drinking water in the US, and a properly made transition is as reliable as any other joint in the system. The key is matching the fitting to the PEX type you have — PEX-A, PEX-B, or PEX-C — since crimp and clamp fittings are generally interchangeable between types, while expansion fittings only work with PEX-A. Check the printing on your PEX tubing before buying fittings. For background on the materials themselves, see our guide to types of plumbing pipes.

The 4 Ways to Connect PEX to Copper

There are four main methods, and each has a place. Push-fit fittings (SharkBite is the best-known brand) push onto the copper pipe on one side and onto the PEX on the other, gripping both with internal teeth and sealing with O-rings. They need no tools at all and are the fastest option, but they cost the most per fitting — typically $8 to $15 in 2026.

Crimp-ring connections use a brass barb fitting with a copper crimp ring squeezed around the PEX by a crimp tool. Clamp-ring (cinch) connections are similar but use a stainless steel clamp ring tightened by a cinch tool. Both are cheap per joint — the fitting plus ring costs $2 to $4 — but each needs a dedicated tool that costs $40 to $100. The fourth method is a soldered adapter: a copper fitting with a PEX barb on one end, soldered to the copper pipe and crimped or clamped to the PEX. It needs soldering skill but produces the most traditional, permanent joint.

Which method should you choose? For a single repair, push-fit is the obvious answer — one fitting, no tools, done in minutes. For a whole-house repipe or a big remodel with dozens of connections, crimp or clamp pays for itself quickly in fitting savings. For a connection that will be buried in a wall or under a slab, many plumbers prefer a soldered adapter or a crimp joint over push-fit, since there are fewer parts that could fail out of sight. All four are widely accepted by code, though some local jurisdictions restrict push-fit fittings in concealed locations, so check local rules before burying one.

Method 1: Push-Fit (SharkBite)

Push-fit fittings are the simplest option and the best choice for most DIYers. The fitting has a copper-compatible end and a PEX end, each with stainless steel teeth that grip the pipe and an O-ring that seals it. You cut both pipes square, deburr them, mark the insertion depth, and push each pipe firmly into the fitting until it seats. That is the whole job — no torch, no crimp tool, no waiting for cure time.

Push-fit fittings have real advantages beyond simplicity. They work on wet pipe, which matters when a shutoff valve does not close fully and water keeps seeping. They can be installed in tight spaces where swinging a crimp tool would be impossible. And they are removable — a simple disconnect clip lets you pull the fitting off and reuse it. The main downside is cost, and the secondary concern is that the internal O-ring is a wear item; in normal use it lasts decades, but it is one more thing that can fail compared with a solid crimped joint.

SharkBite is the dominant brand, but other manufacturers make compatible push-fit fittings, and they all work the same way. Make sure the fitting is rated for both copper and PEX and for the pressure and temperature of your system — standard push-fit fittings are rated to 200 psi and 200°F, which covers normal residential use. Do not use a push-fit fitting on a gas line or on a pipe that is out of round or badly corroded.

Method 2: Crimp Rings

Crimp connections are the traditional PEX method and the cheapest per joint. The fitting is a brass piece with a copper sweat end (or a threaded end) on the copper side and a barbed end on the PEX side. You solder the copper end to the copper pipe, slide a copper crimp ring over the PEX, push the PEX onto the barb, position the ring, and squeeze it with a crimp tool. Then you check the joint with a go/no-go gauge to confirm the crimp is correct.

The crimp tool is the catch. A good manual crimp tool costs $60 to $100 in 2026, and you need the right size jaws for your pipe — 1/2-inch and 3/4-inch are the common sizes, and combination tools exist. If you are only making one or two connections, renting a tool or buying push-fit fittings is cheaper. If you are doing a repipe with 30 joints, the tool pays for itself after the first few fittings.

Crimp joints are very reliable when done right, and they are the method most professional plumbers still use for PEX work. The weak points are a ring positioned too far from the fitting shoulder, a crimp made with worn or misadjusted tool jaws, and PEX that was not pushed fully onto the barb. The go/no-go gauge catches the first two problems — always use it, every joint, even when you are in a hurry. If you need a refresher on soldering the copper side of the adapter, see our guide on how to solder copper pipe.

Method 3: Clamp (Cinch) Rings

Clamp rings, also called cinch rings, work like crimp rings but use a stainless steel band with a small tab, tightened by a cinch tool that squeezes the tab. The advantage is that one cinch tool works on every pipe size from 3/8 inch to 1 inch — you do not need separate jaws for each size, as you do with a crimp tool. The tool itself costs about $40 to $70, and the rings cost roughly the same as crimp rings.

Cinch connections are slightly more forgiving than crimp connections in tight spaces, because the tool is smaller and only needs to reach the tab, not wrap around the whole ring. They are also easier to remove: you can cut the tab with a special removal tool or a pair of snips and slide the ring off. Some plumbers feel crimp rings are marginally more reliable long-term, but both methods are code-approved and widely used, and either one is a solid choice.

One practical note: cinch rings and crimp rings are not interchangeable — you need the ring type that matches your tool and your fitting. Do not try to crimp a cinch ring or cinch a crimp ring. Also, both ring types need the PEX pushed fully onto the barb before the ring is tightened. A good habit is to mark the PEX at the end of the barb with a pencil before sliding the ring into place, so you can see at a glance whether the pipe has slipped back.

Method 4: Soldered Adapter

A soldered adapter is a copper fitting with a male or female sweat connection on one end and a PEX barb on the other. You solder the sweat end to the copper pipe exactly like any copper joint, then crimp or clamp the PEX onto the barb. The result is a transition that is soldered on the copper side — the same joint copper plumbers have trusted for generations — and mechanically fastened on the PEX side.

This method is popular for transitions that will be concealed inside a wall, because the copper side has no O-ring and no moving parts. It is also the natural choice if you already own soldering tools and are comfortable using them. The downside is that it combines two skills — soldering and crimping — and it takes longer than a push-fit fitting. You also need to solder before attaching the PEX, since the heat of the torch would melt the plastic if the PEX were already connected.

When soldering the adapter, keep the flame away from the barb end and let the fitting cool fully before pushing the PEX on. A hot barb will soften the PEX and produce a weak connection. If the transition is in a tight spot, consider soldering the adapter onto a short stub of copper on the workbench, letting it cool, then connecting the stub to the main line with a coupling.

Step-by-Step: A Push-Fit Connection

Here is the full process using a push-fit fitting, the method most DIYers should start with. First, shut off the water and drain the line. Cut the copper pipe square with a tubing cutter and the PEX with a PEX cutter — a clean, square cut matters on both sides, since the O-ring seals against the outside of the pipe. Deburr the copper end and remove any burr from the PEX end.

Next, check both pipe ends. The copper must be clean and round — if it is dented, out of round, or covered in green corrosion, sand it smooth or cut back to clean pipe. Push-fit fittings will not seal on a damaged pipe end. The PEX end must be free of nicks and scratches near the cut, since a scratch under the O-ring is a leak path. If the PEX end is damaged, cut off an inch and try again.

Mark the insertion depth on both pipes using the depth gauge printed on the fitting or a separate depth tool. This step is easy to skip and important to do: the mark tells you whether the pipe went in all the way. Push the copper pipe into the fitting until it hits the internal stop and the depth mark is flush with the end of the fitting. Then do the same with the PEX. Tug both pipes firmly — a seated push-fit connection will not pull out. Turn the water back on slowly and check for leaks. If a joint weeps, push the pipe in further or remove the fitting, check the pipe end, and try again.

Mistakes and When to Call a Pro

The most common mistake is a pipe that is not pushed in all the way. Always mark the insertion depth and check the mark after assembly. The second is a pipe end that is not square or not deburred — a burr can cut the O-ring in a push-fit fitting or prevent a crimp ring from seating properly. The third is using the wrong PEX type with expansion fittings, or mixing up crimp and cinch rings and tools.

Another common error is soldering too close to an existing PEX connection. Copper conducts heat a long way, and soldering a joint near a PEX fitting can melt the PEX or damage an O-ring. If you must solder near PEX, wrap a damp rag around the copper between the joint and the PEX as a heat sink, and keep the flame brief. The same warning applies to push-fit fittings with plastic components — keep the torch away.

Call a professional if the transition is on the main water service, if the copper pipe is badly corroded and keeps crumbling when you cut it, or if you are connecting to a line you cannot shut off. A plumber can freeze the pipe or shut off the water at the street and make the transition cleanly. For help finding one, you can reach a local plumber at (877) 762-1902. For related reading, see our guide to connecting ABS to PVC and our plumbing pipe installation guide.