Figure 1: Irrigation fittings range widely in design and function.
Irrigation fittings connect various parts of an irrigation system. There are various types of these fittings, each with specific functions such as changing the direction of water flow, connecting pipes, or controlling water pressure. This article provides an overview of the common fittings used in irrigation systems, explaining their roles and how they contribute to water management within these systems.
Elbow fittings facilitate directional changes in piping. These fittings, usually available in 90-degree and 45-degree angles, are used to navigate obstacles, change the piping direction for optimal layout, or connect pipes that cannot align due to their fixed orientation. Irrigation water distribution networks traverse varying landscapes and meet specific design criteria. Elbows help maintain a seamless and efficient flow of water throughout the system.
Figure 2: A brass irrigation elbow fitting
Tee fittings branch the main water line into one or more subsidiary lines, allowing for a more complex and extensive irrigation network. These T-shaped connectors provide a junction that splits the water flow into different directions, enabling the system designer to create a layout that can efficiently water multiple zones or areas within a landscape.
Figure 3: A PVC irrigation tee fitting
Cross fittings connect four pipes at a single point, creating a junction that allows for the simultaneous distribution of water in multiple directions. These cross-shaped connectors are particularly useful in complex irrigation layouts where a perpendicular two-way split off a main water line is insufficient and an additional two-way split is needed. This capability is especially beneficial in larger, more intricate irrigation setups where precise control over the direction and division of water flow is critical for achieving thorough and balanced coverage across all sections of the cultivated area.
Figure 4: A PVC irrigation cross fitting
Coupling fittings are primarily used to connect two pieces of pipe of the same diameter to extend the irrigation line's length or repair a damaged section of piping. These straight connectors ensure a secure and leak-free junction, maintaining a continuous and consistent water flow through the system. By using couplings, one can easily modify or expand an existing irrigation network to cover new areas or adjust to changes in the landscape design. They are also invaluable for routine maintenance, as they allow for quick and efficient replacement of worn or broken segments of the pipeline.
Figure 5: A nickel-plated brass irrigation coupling fitting
Reducer fittings connect pipes of different diameters, allowing a smooth transition from a larger-diameter pipe to a smaller one or vice versa. These fittings are useful for an irrigation layout that gradually decreases water flow or pressure as the water moves away from the main supply line towards the individual emitters or sprinkler heads. Reducers allow the system to adapt to the varying flow rate and pressure requirements of different zones within the irrigation network, ensuring that each area receives an appropriate amount of water.
Figure 6: A PVC irrigation reducer fitting
Cap fittings are common irrigation pipe fittings, mainly used to seal off the end of a pipe, preventing water from leaking out and ensuring that the flow is directed only to the designated emitters or sprinkler heads. Their primary function is to create a watertight closure at the end of an irrigation line, which is necessary for maintaining the system's pressure and efficiency. Caps also provide a clean and accessible endpoint for future expansions or modifications to the irrigation network. During maintenance or system alterations, caps can be removed to allow for flushing debris from the pipes or to extend the pipeline further. Learn more about how these fittings work by reading our article on how to cap off a copper pipe.
Figure 7: A stainless steel irrigation end cap fitting
Barbed fittings are used in low-pressure irrigation systems, particularly in drip or micro-irrigation setups, due to their primary function of securely connecting flexible tubing or hoses without clamps or adhesive. The barbs are small, pointed ridges on the fitting that grip the inside of the tubing as it is pushed onto the fitting. Once installed, hose clamps fit around the hose, creating a tight seal that resists leaks and disconnection under normal operating pressures. The simplicity and ease of installation make barbed irrigation fittings popular among gardeners and landscapers, as they can quickly assemble or modify their irrigation systems to adapt to changing garden layouts or plant water requirements without specialized tools or complex procedures.
Figure 8: A plastic irrigation barbed tee fitting
Hose end fittings are specialized attachments designed for the endpoints of garden hoses and irrigation lines, providing a secure, watertight connection between the hose and various irrigation components such as sprinklers, nozzles, or faucets. Irrigation hose fittings typically have threading or a quick-connect mechanism that simplifies attaching and detaching the hose, allowing for easy changing of end devices and facilitating convenient access for water supply adjustments or maintenance tasks.
Figure 9: A plastic irrigation hose end fitting
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Irrigation fittings are made of various materials. The following table outlines the most common materials and the selection criteria to consider when selecting a material for an irrigation fitting.
Table 1: Selection guide for irrigation fitting material
Polyvinyl chloride, or PVC, is widely used in irrigation systems, both above-ground and buried. With many fittings regularly available, including slip, threaded, and push fit, the configuration options are endless.
Read on to learn more about what to consider when choosing pipe fittings for irrigation applications.
Both schedule 40 and schedule 80 PVC piping are commonly used in irrigation systems. Gray in color to differentiate from schedule 40, schedule 80 has thicker walls, making it stronger. That design increases PSI, but can also restrict flow. It's typically used in above ground systems. Schedule 40 PVC, on the other hand, is white with thinner walls. While it can handle heavy flow, it's best used in drainage, irrigation, and cold-water applications. Schedule 40 piping is also lighter than its counterpart, making it less expensive and a bit easier to work with.
Fittings for PVC are measured the same way, in schedule 40 and schedule 80 options. You'll notice that they will fit interchangeably, but it's best to use the same schedule pipe and fitting. This will ensure a consistent strength throughout the irrigation system.Commercial Industrial Supply
You might see the connections for PVC fittings described as 'SSS,' 'ST,' 'SST,' etc. The 'S' stands for slip, socket, or spigot. These connections have no thread and are solvent welded, which means that a cement glue is applied to both the pipe and the fitting. The acetone in the cement glue allows the pipes to melt together, forming a very tight seal.
The 'T' in these fitting configurations stands for 'threaded.' In threaded fittings, the pipe is twisted to fit securely into the fitting. However, threaded joints need a sealer as well. The sealer lubricates the parts, making it easier to thread the pieces together. It also creates a stronger seal. Teflon tape is commonly used to seal threaded joints. It's easy to use and less messy than other options. Pipe dope is often used as a sealer in other applications, but it has the consistency of a thick paste and could gum up the nozzles of the sprinklers in irrigation systems, so it's not recommended.
Some common PVC fittings for irrigation systems include:
Exposure to Sunlight
PVC piping is known for its strength, but it can become brittle when exposed to long periods of sunlight. This isn't a problem for underground irrigation systems, but buried irrigation may not always be possible. In order to avoid exposure to sunlight in above-ground irrigation, you can apply several coats of an exterior latex paint or use foam pipe insulation. Both will help to block sunlight and avoid leaks or cracks caused by brittle pipes.
In-ground irrigation systems should always be buried at least 10 inches deep. This depth could minimize the likelihood of being struck with a shovel or other tool, which could easily lead to cracking and breaking. Pipes that are not buried deep enough may also float to the surface in winter. In areas where temperatures consistently dip below freezing, you may want to consider using foam pipe insulation. Winterizing, where all water is flushed out of the system before the winter season, will also be necessary to avoid pipe breaks in the off-season.
It's quite easy to install and connect PVC piping and fittings in irrigation systems. Before you get started, make sure to measure, keeping in mind that the pipe will slide all the way into the shoulder of the fitting once connected, which means you'll need to measure the distance between the shoulders. Make the cut as clean and square as possible, removing any burrs that may be left inside the joint with a utility knife. Next, use a fine grit sandpaper to lightly scuff the end of the pipe and remove any caked-on dirt, then wipe away dust with a clean, dry cloth. Doing a dry-fit is important as well. Assemble all the pipes and fittings to be sure they are the correct length before cement glue or sealant is applied.
When connecting slip fittings, don't forget to prime. This temporarily softens a thin layer of PVC so that the cement glue can bond the two pieces together. Apply a layer of primer on the outside end of the pipe as well as the inside of the fitting. Then, brush the cement onto the end of the pipe and inside the fitting, making sure to cover all points of contact. Slide the pipe into the fitting until it meets the shoulder. Give the pipe a slight turn to evenly distribute the cement, and hold it firmly for 30 seconds to a minute until the cement cures.
Threaded fittings will also need a sealant. Before you choose one, check to make sure that it is compatible with PVC piping. Teflon tape is an easy and effective sealant for threaded PVC fittings. In the same direction as the threads, wrap male ends with three layers of tape, leaving the top thread empty. While it's important to ensure that the pipe is securely in the fitting, be sure not to overtighten, as this could cause cracking or breakage.
Push fit fittings are an optimal solution for many different applications. They can be used with copper and CPVC piping as well, but they are more commonly used in PVC irrigation systems. Push fit fittings are readily available at many hardware stores, and they are quick, easy, and much less messy than slip and threaded fittings. Glue is not required, so there's no dry time. You can also use push fit fittings when pipes are wet, as long as they are clean, so systems won't need to be shut down for extended periods of time.
Just because they are easy to use does not mean they are any less strong. Metal barbs inside the fitting grip the surface of the pipe once it is pushed in. Combined with a rubber O-ring, push fit fittings create a watertight seal that cannot be removed. The only way to remove a push fit fitting is to cut the PVC pipe, which means that dry-fitting your pieces before installation will not be possible. PSI and water temperature limits vary, so it's always a good idea to consult the manufacturer's specifications before purchase and installation.
With so many options for PVC piping and fittings available, irrigation system configuration possibilities are endless. First, decide whether you should work with schedule 40 or schedule 80 pipes and fittings. Then, choose the fitting style, whether slip, threaded, or even push fit, and determine the types of fittings you need to get the job done. Don't forget the primer, cement glue, or Teflon tape either. When installing above-ground systems, be sure to minimize exposure to the sun, either by applying several layers of exterior latex paint or using a foam insulation. Buried systems should be at least 10 inches below the surface and should be winterized in areas where the temperatures often dip below freezing. As always, check each manufacturer's product specifications to ensure proper use.