How Irrigation Systems Operate

Plants thrive where they have access to enough water – it's as straightforward as that. If a stream dries up or the climate shifts, plant species dependent on it will die. Conversely, when an area that was previously dry begins receiving regular rainfall or if a river shifts its course, new plant life will flourish where the water flows. Vegetation follows its vital resources, either flourishing or perishing based on their availability.

At some point, humans sought to cultivate specific crops in regions where they might not naturally flourish. This marked a key moment in the agricultural revolution, when our ancestors learned to grow crops and create surpluses. Eventually, humans also sought to create manicured yards and gardens, often in areas where only wild plants or no vegetation at all would typically grow. To accomplish this, they mastered the practice of irrigation, bringing water to the land artificially. In its simplest form, this meant manually transporting water by hand. On the more complex end, humans diverted floodwaters, built intricate pipe networks, and created artificial channels to nourish their gardens and farms.

To move water from point A to point B without the need for excessive bucket carrying, damming, or constructing canals, you must direct it through irrigation systems. Just as power lines carry electricity, irrigation lines transport water to gardens, lawns, and crops. In some cases, they also serve as the means of distributing the water, as we'll explore in the next section. Irrigation lines are essential in nearly every type of automated irrigation system, whether you're purchasing an $8 soaker hose for your lawn or spending several hundred dollars per acre on professional agricultural irrigation.

In this article, we will examine how irrigation lines enable us to irrigate crops, lawns, and gardens, as well as the potential issues that may arise.

Water in the Veins -- Irrigation Techniques

Irrigation comes in many forms, but the types of irrigation lines fall into three primary categories: surface, subsurface, and elevated. Whether you're transporting a large amount of water, distributing it across different areas, or irrigating various plants, you can either bury the line beneath the soil or leave it aboveground. Each of these methods offers its own unique benefits.

A subsurface irrigation line is hidden from view, making it less of an eyesore and preserving surface space. However, just because it's buried doesn't mean it won't require maintenance or break down. On the other hand, surface irrigation lines are easy to repair since you don’t need to dig them up, but they are exposed to potential damage from people, machinery, and animals. Elevated lines are also used in some systems, allowing sprinklers to cover larger areas. Though these systems need additional supports and higher pressure, making them costlier, they can be the most effective. One popular type of elevated irrigation system is the wheel move irrigation system, where the line serves as the axle for large rolling wheels.

Irrigation lines are made from a variety of materials, including metals, wood, and even stone. A common choice today is polyvinyl chloride or PVC piping, a durable plastic often found in plumbing. Many companies offer PVC specifically designed for irrigation lines in different grades and sizes. However, PVC is not invincible—over time, it can degrade, particularly under high pressure, large volumes, or water hammer (the noise produced when water flow is abruptly stopped). PVC pipes are joined using couplings and cement.

Another widely used material for irrigation lines is polyethylene tubing, or high density polyethylene (HDPE) pipe. This black, flexible tubing is easier to install than PVC. The sections of poly pipe are connected with clamps, couplings, or even heat fusion.

In many cases, an irrigation line simply serves as a conduit to carry water from the source to the sprinkler or other water delivery system. However, in some systems, the irrigation line itself is the means of water distribution, with sprinklers mounted along its length or perforations in the tubing releasing water directly. This is the method used in subsurface drip irrigation, where water seeps out of buried, perforated tubing and delivers moisture directly to the plant roots, bypassing the soil's surface.

What issues might arise with irrigation lines? Discover the details on the following page.

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Problems and Solutions for Irrigation Lines

Damaged irrigation lines can create significant problems. If water escapes through a broken pipe, nearby plants might get flooded while others go without. Even a small leak can reduce water pressure and flow. In some cases, a large leak could damage property or cause mudslides. It's essential to prevent these issues by maintaining your irrigation lines and knowing how to fix them when things go wrong.

One simple factor to consider is compacted soil. When something is buried underground, what happens if a dump truck drives over the area? The pressure from vehicles, people, or pets can compact the soil and potentially crush the irrigation lines—unless the material used is sturdy enough to withstand that pressure. Similarly, as shown in the photo, working in your yard and forgetting about subsurface irrigation lines can lead to damage. If the lines are aboveground, the risk of damaging them with lawnmowers or farm equipment increases.

Cold temperatures can present another challenge for irrigation lines. If water freezes and expands inside the pipes, it could cause them to burst. To avoid this, many people make sure to drain most of the water from the lines in winter. More flexible materials are better able to handle the expansion and contraction caused by freezing temperatures. As a result, landscapers often opt for poly pipe in cooler areas and PVC in warmer climates.

Like any plumbing system, irrigation lines are susceptible to internal clogs. The key to avoiding this issue is to ensure the water passing through the system is properly filtered. Gray water systems, in particular, are prone to blockages since the water can contain food particles, hair, or other debris. If these particles accumulate inside the pipes, they can clog the system and block water flow.

Animals can present a threat to irrigation systems—not just your mischievous dogs and goats, but also wild creatures. Coyotes, gophers, and other rodents are known to gnaw on poly pipe irrigation lines, mistaking them for food. Plants can cause problems too. If you think your subsurface irrigation system is safe, you might be in for a surprise as nearby tree roots could invade the system over time.

Repairing a broken irrigation line typically involves two steps: identifying the location of the break and either patching it or replacing the damaged section. Advanced systems use sensors to detect pressure drops, pinpointing the source of the break, which is especially helpful in subsurface setups. If sensors aren't available, a visual inspection can often do the trick. For aboveground pipes, you'll notice the leak as soon as the water starts flowing. For underground pipes, a damp patch in the soil above the break usually signals the issue. Once located, the next step is to turn off the water, dig down, and either patch or replace the damaged pipe section.

The type of material used in your irrigation lines dictates how you'll go about patching them. A welding torch may be effective for metal pipes, but for PVC, you'll need to cement the replacement sections at the couplings, while poly pipes typically require clamps to secure the new parts.