Plastic vs. Brass PEX Fittings: Know Between Them

When it comes to PEX fittings, the preference for Brass is slowly diminishing. If you look at what people are buying today, you’ll see most of it is plastic PEX fittings.

Plastic vs Brass PEX Fittings

Is it because plastic PEX fittings are better? The answer isn’t so straightforward. Brass fittings usually cost 5 times as much which probably has something to do with the market share.

Leaving those aside, if we put Plastic vs Brass Pex fittings, who will win the battle for quality? Professional plumbers prefer both in different circumstances.

You shouldn’t pick a favorite one either. Why? Well, that is what we’ll discuss in this article.

What Are Plastic PEX Fittings?

What Are Plastic PEX Fittings

These are a type of Poly fittings specially made to use with PEX tubing. Nowadays, these are preferred more due to the convenience and the reduced cost.

The concern with Plastic fittings is that they are less durable in the long run. Plastic fittings indeed deteriorate if they are exposed to the sun or, more specifically, Ultraviolet rays.

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Benefits of Plastic PEX fittings

Benefits of Plastic PEX fittings

It isn’t without reason that a group of plumbers prefer plastic fitting. There are quite a few things to like about them.

Cheap and Availability

The first motivating factor for anyone, including me for considering plastic poly fittings is that it’s cheap. Depending on where you live and the vendor, plastic PEX fittings can be 4-5 times cheaper than their metal counterparts.

And also, plastic fittings are easier to store, which means you can keep them longer on shelves. That is why these fittings are seen to be available in stores all the time.

Good Durability

The term plastic shouldn’t scare you off. I mean, professional plumbers rely on them without hesitation, which should tell you about their quality. The plastic in these fittings is a type of polymer that can handle insane pressure without ever buckling down.

If you keep them away from the sun’s exposure, there is little need to go for alternatives.

No-Risk of Corrosion

Another beautiful perk of plastic fittings is the zero risk of corrosion. You can keep them in service for years without worrying about replacing corroded fittings. This is a significant factor in preferring plastic over metal.

If the water in question is of poor quality, i.e., it includes pollutants and oxidizing agents, plastic fittings are your best bet.

Less Leakage

One of the notable features of poly PEX fittings is that they don’t experience leaks easily. Even after being in service for a decade, it should be working as well as new.

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Usable in Many Conditions

No matter the water quality, a plastic poly PEX fitting is sure to work. In places where the water has many pollutants, especially if the water is acidic, these plastic fittings are considered to be the ideal solution.

Negatives of Plastic PEX fittings

Negatives of Plastic PEX fittings

Well, it also has some things that you may not like. Here are the notable cons:

Narrow Inside Diameter

A clear negative of using plastic PEX fittings is the narrow open area inside. Since plastic is a weak material, it needs a thick wall to provide the required amount of durability.

This is according to the ASTM2159 standards. And that means the open area inside has to be smaller than metal fittings of the same size. A smaller diameter means you have a smaller water flow area.

UV-Ray Exposure

If the plastic fittings become exposed to the sun, the UV ray will affect it to the point it starts to become weak, and leaks will start to show up.

Weaker Than Metal

There is no denying this very simple fact. Plastic is weaker than metal, and it has a much higher chance of getting punctured. So, for outdoor use where it’s exposed to all sorts of things, it’s never a suitable option.

What Are Brass PEX Fittings?

What Are Brass PEX Fittings

These are simply PEX fittings made of brass alloy. In the past, they were unequivocally the best option anyone had. They are still the same, but the alternatives have become better, which means they are not the only option.

Brass PEX fittings are used to connect different segments of PEX piping. The only acceptable brass fittings are those made according to the ASTM F1807 standard.

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Benefits of Brass PEX fittings

Plastic vs. Brass PEX Fittings: Know Between Them

Brass fittings are one of the most purchased amongst its competitor. Here are the reasons:

Stronger and Durable

Brass is the typical choice if you want a stronger fitting. It’s metal, so there’s much less of a chance of it buckling down to impact forces.

Not only that, but it can also withstand a higher amount of internal pressure. So leaks are the least of your worries.

Withstands High Temperature

Even in higher temperatures brass fares better due to its expansibility. That is why brass PEX fittings are used in factories where the flowing fluid is warmer. In the automotive industry, brass fittings have a special place just for this reason.

In recent days, however, steel PEX fittings have begun replacing them.

Negatives of Brass PEX fittings

Negatives of Brass PEX fittings

Well, it also comes with its baggage. For example:

Chances of Corrosion

Since Brass is a combination of copper and zinc, it’s more susceptible to corrosion than a pure copper fitting. The zinc in its walls is the weak point. With a thinner wall, corrosion and rust is likely the worst thing to happen to it.

Simply due to that, it can’t handle poor quality water such as acidic water.


Compared to other options in the market, brass fittings are considered expensive. It may have been a clear winner, but the cost vs value ratio doesn’t seem to be in its favor.

Difference Between Plastic and Brass PEX fittings

Difference Between Plastic and Brass PEX fittings

As you can see from their list of perks, they are different. Although this difference doesn’t reduce their utility, it can be extremely worrying if you use the wrong one in the wrong place.

Here are the differences between them so that you can understand which to choose in different circumstances.

Strength and Durability

When it comes to strength, the difference between Plastic and Brass is pretty apparent. Brass will have the most resistance to internal and external forces. But for withstanding normal internal water pressure, both Brass and plastic will perform the same.

Corrosion Resistance

Brass fittings are made of copper and zinc. Although they are made to be resistant to corrosion, long exposure to water can cause issues. If exposed to poor quality water, such as acidic water, brass fittings will corrode over time.

Fortunately, plastic fittings do not corrode.

Exposure to Sun

But plastic poly fittings can start to lose durability if exposed to the sun’s UV rays for a long period. So, it’s not a good option to use in outdoor conditions.

In such cases, brass fittings are the ideal solution.

Withstanding Pressure

Both the brass and plastic PEX fittings follow the ASTM standard of 100psi pressure. It means they will withstand 100psi of pressure without an issue.

However, there are severe circumstances where the water can freeze, or gas can form inside the pipes. In such cases, plastic PEX fittings cannot withstand the extra pressure, whereas brass fittings are strong enough to hold their own.

But if that were to happen, the main pipeline would burst before any of the fittings.

Withstanding Temperature

Brass fittings can withstand much higher temperatures compared to plastic fittings. That is why Brass is the preferred product in factories like the automotive industry.

Plastic fittings have a weaker structure that makes them unusable in such conditions. No plastic pipe or fittings can be used near a water heating device.

Flow Area

One important factor when it comes to water fittings is the flow area. If the flow area is larger, more water can pass through it. Brass fittings are manufactured according to the ASTM-F1807 standard. And plastic PEX fittings have to follow the ASTM-F2159 standard. You can see the fixed dimensions in the chart below:

Plastic vs. Brass PEX Fittings: Know Between Them

As you can see, the ASTM standard has different wall thicknesses and inside diameters for brass and plastic fittings. And this translates into the difference in flow area. If you look at the blue column in the chart, Brass PEX fittings have a 33% larger flow area than plastic fittings on average.

You should select the one that fits your requirement.

One Small Suggestion

Many poor-quality brass fittings are imported from China and Korea. These can fool you into buying them.

So, when you buy the brass fittings, make sure to look for the seal of ASTM and third-party organizations such as NSF (National Science Foundation) or ULC (Underwriters Laboratories of Canada).

Frequently Asked Questions

1. Is Brass ok for water fittings?

Yes, brass fittings produced to use in water supply lines are lead-free. In other words, it’s not toxic.

2. How long do brass fittings last?

Brass fittings can last up to 100 years in the most ideal conditions. It has a longer lifespan even compared to copper fittings.

3. How long do plastic fittings last?

Plastic poly fittings have a shorter lifespan compared to Brass. But they still have a respectable lifespan of 50-75 years.

Final Words

So, what’s the verdict? Is Brass better than plastic PEX fittings? I always like to stay in the middle. In my opinion, both of them have something to offer that the other one doesn’t.

Depending on the circumstances, plumbers take advantage of both materials. Why should we think otherwise? If you care about the money, plastic PEX fittings are simply the most cost-effective option.

But if you have a special need for brass fittings such as industrial applications, you know what you have to do.

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