Irrigation pipe products are evolving to make systems more efficient and installations quicker and easier.

When it comes to irrigation pipe, contractors have strong opinions.

“Users of PVC will argue that it’s the best, and users of polyethylene will say that’s the best,” says Scott Knowles, president of Wolf Creek Co., a distributor of landscape, irrigation, lake management and drainage supplies based in Trotwood, Ohio. “It’s a never-ending argument.”

But despite their personal preferences, experts agree that contractors should be open to different varieties and new products and should consider soil type, environmental temperatures, water pressures, elevation changes and other project factors before choosing one or the other to ensure the system runs as efficiently as possible.

“Pipe is directly related to the hydraulics of an irrigation system, and if you don’t get that right, the system won’t perform as it should or will become a maintenance nightmare,” says Knowles. “That’s not good for the installer or the end user.”

Polyvinyl chloride (PVC) and polyethylene are the two most common types of pipe used for traditional irrigation systems. While irrigation experts recognize that both types of pipes work, there are some notable differences.

PVC is available in 20-foot lengths of rigid pipe that needs to be connected by a coupler or fitting. Polyethylene typically comes in 100- to 300-foot coils, so a much longer length of pipe can be installed before a fitting is required. It also can be easier to transport, as the coils fit in any truck bed. Because of its rigidity, PVC pipe is known to crack and shatter in freezing temperatures, but the pipe has a higher burst pressure. Polyethylene is made of a softer plastic that is more flexible in extreme cold and is also more effective in sandy soils.

The type of pipe used generally varies region to region but often comes down to a contractor’s personal preference.

“Habits and what products have been used in the past are the primary factors used to base irrigation pipe selections,” says Tim Ricamore, central procurement manager for SiteOne Landscape Supply in Troy, Mich. “This has been the case for many years, as the habits of contractors are difficult to change.”

Jess Stryker, a retired landscape architect and owner of Jess Stryker & Associates in Ventura, Calif., agrees. He says he always used PVC pipe primarily because it’s what is most commonly used on the West Coast.

“I think the main reason for the West Coast using PVC versus the East Coast using poly tube is just habit,” he says. “It’s just how things have been done.”

Change coming?

Contractors may be prompted to change their ways, as products evolve, systems become more efficient and installations become easier. In PVC pipe, there has been an ongoing trend toward the use of reclaimed water pipe, commonly known in the industry as purple pipe. It’s driven by a growing emphasis on water conservation and reuse, particularly in areas where water is a limited resource.

“When it’s determined that nonpotable, nonpurified water can be used for the purpose of irrigation, purple pipe will be specified and used on a given project,” says Ricamore. “This type of pipe has seen a significant increase in usage over the past 10 years.”

High-density polyethylene, or HDPE, is another emerging trend, particularly in commercial landscape and golf course applications. It comes in pipes measuring 2 inches wide and larger, has thicker walls and is made of denser material. Also, HDPE pipe doesn’t require fittings. It’s heated up and welded together. Knowles says this difference makes HDPE ideal for irrigation system main lines because it reduces the risk of breaks or cracks.

“When done properly the weld joint is stronger than the pipe itself,” he says. “On every pipe network, the weakness is the fittings, not the pipe—that’s where you get cracks because of surge pressures and velocities that are too high. By eliminating fittings, you’re eliminating points of failure.”

The introduction of 4710 resin in the production of HDPE began about three years ago, and has since become industry standard, replacing the 3408 and 3608 resin products used in the past. This change has allowed the pipe’s pressure requirement to be met using less material, providing a production advantage to the manufacturer. As the dimensions of the pipe are reduced, the pipe becomes more flexible and easier for contractors to install. These changes also provide advantages in coiling, which reduce shipping costs for distributors.

Cross-linked polyethylene, or PEX, pipe is another product making its way into the irrigation industry. PEX is made of HDPE, but cross-linked bonds in the structure of the polymers make it stronger. It has a higher burst pressure, which is great for high-pressure mainlines, Stryker says, and PEX can withstand freezing temperatures so it can be used in any environment.

“I expect we will see more irrigation systems everywhere using flexible piping systems with PEX for mainlines and poly for laterals,” Stryker says.

When it comes to fittings, “Push-to-connect” fittings are gaining popularity. They’re quick and easy to install, saving contractors time and money. The tube is simply pushed into the fitting, eliminating the need for soldering, clamps, glue and even tools. An O-ring is used for sealing, and a grip ring holds the tube in place. These fittings are available for polyethylene and PVC pipes, and they also work with PEX.

“It’s really easy and quick to press those fittings on the end of a pipe and be done compared to the insert fittings needed for poly or the solvent weld fittings for PVC, which have to be clamped or welded together,” Knowles says. “That takes more time and also introduces a possible point of failure if it’s not done right.”

Photo: WOLF CREEK CO.