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Critical Considerations for Plumbing Systems in Residential Construction

By: Jonathan Simon on March 12th, 2024

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Critical Considerations for Plumbing Systems in Residential Construction

Contractors  |  Homebuilders  |  residential plumbing  |  CPVC

As builders and plumbers plan for new construction, the choice of plumbing materials deserves special attention. While homebuyers generally don’t understand the differences between the major plumbing systems in use today, those differences can affect a builder’s reputation, the plumbing contractor’s profitability, and the homeowner’s satisfaction. Here are the four most important considerations when selecting plumbing materials for new construction. 

1. Compatibility with Local Water Conditions

The most important, and often the least considered, factor in selecting plumbing materials is compatibility with local water conditions. Plumbers and builders too often assume that every residential plumbing system on the market is capable of handling their local water conditions, but that’s not necessarily the case.

Copper and PEX can both be susceptible to premature failure due to incompatibility with local water conditions. Just recently, a top 30 builder settled a class action lawsuit that claimed the copper plumbing used in a particular development failed prematurely because the pipes “were defective for the water conditions present.”

That wording is important because the suit didn’t claim the products were defective due to poor manufacturing. It claimed they weren’t suitable for the application—residential plumbing—due to incompatibility with local water conditions.

This is, of course, not the first class action lawsuit that has claimed copper or PEX piping failed prematurely due to corrosion and degradation caused by disinfectants used commonly in U.S. water treatment—and it probably won’t be the last. While class action suits have occasionally targeted the material manufacturer, builders are also commonly targeted in these suits by upset homeowners.

Whether the builder was involved in material selection or trusted their plumbing contractor with this important decision is irrelevant when it comes to legal action. In new construction, builders and plumbers could be held responsible and risk having to pay the price in terms of settlement costs and reputation damage.

And they shouldn’t expect much help from material manufacturer warranties. Most warranties from PEX and copper piping manufacturers contain “exclusions” for damage to the system caused by water conditions. In other words, the warranty does not cover damage to the pipe caused by the chlorinated water running through the pipe.

While builders and plumbers may be held legally responsible for selecting materials that are compatible with local water conditions, it can be extremely difficult for them to know the true chemical composition of the local water supply, especially since municipalities can and do change their treatment practices in ways that can increase the risk to previously installed PEX and copper pipes. Fortunately, the reliability of CPVC is not dependent on local disinfection practices. FlowGuard Gold CPVC is immune to degradation from chlorinated drinking water and performs reliably in all potable water conditions. If the water is safe to drink, it is safe for FlowGuard Gold CPVC.

2. Impact on Water Pressure and Flow

Poor water pressure at fixtures can be frustrating for homeowners and the insert fittings used by PEX create a larger pressure drop than the socket-style fittings used by copper and CPVC. Even expansion PEX fittings have a much smaller internal diameter than a CPVC fitting. In a ½” 90-degree elbow, a PEX expansion fitting can create a pressure drop up to six times that of a CPVC fitting.

New Plumbing Pic

This becomes particularly problematic when plumbing luxury showers that include body sprayers. Due to the number of fittings required to balance the flow and pressure within and across the various loops in these systems, and the pressure drop created by each PEX fitting, the only way to ensure sufficient pressure in a luxury shower using PEX is to upsize the loop piping and the branch line by one or two sizes, increasing system costs. In a luxury shower, FlowGuard Gold CPVC will always provide better flow and pressure than PEX, which can enable smaller pipe sizes in these types of installs.

Hot water recirculating systems are another example of where PEX can limit flow rates. Possibly due to concern over the material’s vulnerability to chlorine degradation, some PEX manufacturers and model codes limit water velocities in PEX to 2 feet per second in hot water recirculating systems. That can dramatically reduce flow rates across the system and may require upsizing the piping to deliver adequate volume. FlowGuard Gold CPVC reliably supports velocities of 8-10 feet per second in hot water recirculating systems, eliminating the need for upsizing and allowing the full benefits of the system to be realized.

3. Speed and Cost

There’s a common misperception in the industry that PEX installs faster than CPVC and that time savings offset the higher cost of PEX materials. Not surprisingly, that claim arose from PEX manufacturers who can’t deny that CPVC is less expensive—especially after one PEX manufacturer published an analysis that confirms a significant cost difference between the two systems that didn’t even factor in the upsizing that is often required to compensate for the pressure drop introduced by PEX fittings. It’s much easier to create biased comparisons of installation time that aren’t based on real-world conditions.

However, in a time study conducted by the NAHB’s Home Innovation Research Labs, CPVC installed about 15% faster than PEX in trunk and branch configurations. PEX did install 10% faster than CPVC in mini-manifold systems, but the material costs associated with mini-manifold designs offset any time savings. As a result, the study concluded:

Given that the most common plumbing installation method today for PEX (trunk and branch configuration) has the slowest installation time in our study, this study suggests that builders and plumbers may be able to realize time and cost savings through the use of other plastic materials and system designs.

The primary reason that CPVC installs faster than PEX comes back to the type of fittings used. The process of connecting CPVC pipes and fittings is easier and faster than that of PEX, as demonstrated by the FlowGuard Speed Test Challenge. What’s more, the solvent weld process used with CPVC chemically fuses the fitting and pipe into a single piece of CPVC that is 225% thicker than the pipe itself and stronger at the fitting than the pipe alone. That has a number of benefits to plumbers and builders, including enabling CPVC to be used under slab, which can create further speed and cost savings in some situations. 

4. Proven Reliability 

It can take years for plumbing system reliability issues to surface as the industry found out in the early 1990s with polybutylene. With more than 13 billion feet installed in the United States, FlowGuard Gold CPVC has been the most used, most specified, and most trusted brand of non-metallic pipes over the last 65 years.

It’s that proven reliability that makes it the system of choice for contractors like Atlas Plumbing. “FlowGuard Gold is a time-tested product that trains easily and is price competitive,” Tim Lear of Atlas Plumbing says. “And that’s the whole reason we’ve used it for as many years as we have.”

Reducing cost was a key driver when Powerhouse Plumbing began seeking an alternative to copper. “We started to use PEX when the economy went down,” says owner Mike Burke. “After doing more research on cost and efficiency though, I became more interested in switching to FlowGuard Gold. The PEX piping was more time-consuming to install, and the fittings were more expensive.”

The savings Powerhouse realized from switching to FlowGuard Gold CPVC from PEX proved larger than the savings the company experienced when shifting from copper to PEX. One unexpected benefit was lower inventory costs. “The inventory provides a cost savings compared to keeping PEX materials like multiple fittings and rings in stock,” Burke explains. “I’d rather have money in the bank account than on the shelf.”

Top builder, Homes by Westbay, chose FlowGuard Gold CPVC based on its proven track record. “Pinhole leaks in copper led us to evaluate our options, and with PEX, there isn’t enough historical data and usage to point to long-term durability.” Homes by Westbay’s Brent Dunham says. “As people become more educated on the warranty issues and lawsuits surrounding other plumbing systems, it will become apparent that FlowGuard Gold CPVC is the best choice.”

Repiping specialist Plumbing Express sees firsthand the problems that can arise when unproven materials are used in new construction. “We see problems with PEX in homes that are less than 20 years old,” Blake Mowe of Plumbing Express says. “The material itself and the joining method both contribute to the problems we see.” The company has built a successful business replacing PEX and copper with FlowGuard Gold CPVC.

Builders and plumbers may prioritize each of these considerations differently, but there is one material that satisfies each requirement better than the alternatives: FlowGuard Gold CPVC. For builders seeking to protect their reputation and reduce their liability, and plumbing contractors looking to improve their profitability, a FlowGuard Gold Plumbing System is the clear choice. To see how to specify FlowGuard Gold CPVC in your next project, download our sample specifications.


FlowGuard Gold Sample Specifications for Plastic Plumbing Systems