PEX plumbing has changed the game for DIYers and pros alike. It’s flexible, affordable, and a lot easier to install than copper. But when it comes time to connect those PEX lines, you’ve got a choice to make: plastic or brass fittings?
Both types get the job done, but they’re not created equal. Let’s break down the differences in cost, durability, performance, and when each one makes more sense.
Quick Overview: What Are PEX Fittings?
PEX fittings are used to join PEX pipes together or connect them to valves, faucets, or fixtures. They’re usually installed using crimp rings, cinch clamps, or push-to-connect systems.
The two most common fitting materials are:
- Plastic (Poly Alloy or PPSU) – Lightweight, non-corrosive, typically black or white
- Brass – Heavier, metallic, gold-colored, and highly durable
Now let’s compare them side by side.
1. 💰 Cost Comparison
If budget’s your top concern, plastic wins. On average, plastic PEX fittings cost 20%–30% less than brass.
For big projects—like a full re-pipe—that price gap can add up fast. Many contractors use plastic fittings for this reason alone. And when prices on copper or brass spike? Plastic becomes even more attractive.
2. 🔧 Durability and Strength
This is where brass shines. It’s tougher than plastic, less prone to cracking under stress, and handles higher impact loads. In exposed locations or areas where fittings might take a hit (like behind a washing machine), brass is often the safer bet.
Plastic fittings are plenty strong for most in-wall or under-sink applications—but they’re not indestructible. Over-tightening or freezing conditions can cause cracks over time if you’re not careful.
3. 💦 Corrosion Resistance
Here’s the twist: plastic fittings actually beat brass when it comes to corrosion resistance.
Brass can degrade in aggressive water conditions—especially if your supply contains high levels of chlorine, minerals, or acidic pH. This can cause dezincification (where zinc leaches from the alloy), weakening the fitting and causing leaks.
Plastic fittings, on the other hand, don’t rust, corrode, or degrade from chemicals in the water. That makes them ideal in areas with problematic water chemistry.
4. 🔥 Heat Resistance
Brass has a higher temperature tolerance overall. If you’re running hot water lines—especially in commercial settings or radiant floor heating—brass may hold up longer under extreme heat and pressure.
That said, plastic fittings used in residential hot water lines typically perform just fine within standard operating ranges (up to 200°F).
5. 🔩 Ease of Installation
Both types install the same way using crimp or cinch tools, and both are compatible with standard PEX tubing.
But here’s the thing—plastic fittings are easier to handle and maneuver in tight spaces. They’re lighter and often easier to fit between joists or into awkward corners without adding bulk.
Brass fittings, while sturdier, can be harder to squeeze into snug spots. And if you’re working overhead or on a ladder, that extra weight gets old fast.
6. 🔧 Code and Inspection Approval
Both plastic and brass PEX fittings are approved by most plumbing codes in the U.S. and Canada. However, some local codes or inspectors may have preferences. Brass has been around longer and is sometimes preferred in commercial jobs or multifamily buildings.
If in doubt, check your local code requirements—or ask your inspector what they’re used to seeing.
So… Which Should You Choose?
Use plastic fittings if:
- You’re on a budget
- You’re working in a corrosive water area
- You’re installing behind walls or ceilings
- You want lightweight, easy-to-handle parts
Use brass fittings if:
- You want maximum durability and strength
- You’re running high-temperature or high-pressure lines
- You’re working in exposed locations
- Your water is soft or neutral (low risk of corrosion)
Final Thoughts
There’s no one-size-fits-all answer here. Both plastic and brass PEX fittings have their place. It really comes down to your water conditions, project location, and how much you’re willing to spend.
If you’re doing a large-scale install in a house with questionable water quality, plastic might be the smarter long-term play. If you’re outfitting a workshop or high-demand zone, brass is probably worth the upgrade.
Either way, PEX has simplified plumbing for everyone—and both fitting types will serve you well if installed properly.