One crucial aspect of setting up a drip irrigation system is selecting the appropriate tubing or piping. With a myriad of options available, it can be overwhelming to determine which one suits your project best.
What Size Tubing Should I Use for Drip Irrigation?
Selecting the correct size tubing is crucial for ensuring proper water distribution and system performance in drip irrigation. The size of tubing you need depends on the flow rate, pressure, and layout of your system. Here are some general guidelines for choosing tubing size:
Drip Irrigation tubing, can be broken down into three categories:
Mainline tubing or main distribution line. Main Distribution Line: Also known as the header line, this tubing carries water from the water source to the individual drip lines or emitters.
The size of the main line is determined by the total flow rate of the system and the maximum allowable pressure drop. Common sizes for main distribution lines range from 1/2 inch to 1 inch in diameter, with larger diameters used for higher flow rates and longer runs.
Micro-tubing. Micro-tubing is commonly used to describe ¼” tubing. It can be used as mainline tubing, but remember that it cannot be over 30 feet in length or supply more than 30 GPH. This works well for small patio areas, but beyond that micro-tubing is often used to take drippers or other watering devices from the mainline tubing to the plant to apply water directly to the root zone.
A hole punch is used to create a hole in the mainline tubing (½” or greater) where one end of a connector is inserted; the other is connected to a run of ¼” micro-tubing. Even though the micro-tubing is not being used as mainline tubing, it still can’t stretch more than 30 feet away from the mainline tubing.
Dripline tubing. A dripline is a tubing that has emitters embedded directly into the tubing at preset spacings and dripper flow rates.
Dripline tubing can save a lot of time, as there is no need to insert drippers.
You simply lay out your dripline and connect it to your system. Dripline is available in ½” and ¼” tubing sizes with a limited number of standardized emitter spacings and emitter flow rates.
Drip Tape: Drip tape is a thin-walled, flat tubing with evenly spaced drip emitters along its length.
It is designed for surface-level irrigation and is commonly used in row crop farming and vegetable gardens.
Drip tape is lightweight, cost-effective, and easy to install, making it suitable for temporary or seasonal irrigation systems.
What material is used for irrigation?
Polyethylene (PE) Tubing: PE tubing is the popular choice for drip irrigation systems due to its flexibility, durability, and affordability. It is resistant to UV rays, chemicals, and abrasion, making it suitable for both above-ground and buried applications.
PE tubing is available in various diameters and wall thicknesses to accommodate different flow rates and system layouts. Regardless of the type of tubing selected for your project, there are two pieces of information that are critical when selecting tubing: run length and total flow rate.
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What is the length your longest run of tubing needs to be? How many gallons per hour will your system be requiring? To choose the right tubing for your project, both factors need to be considered, but at this moment, let’s look at each separately.
Run length. Maximum run length is the longest length for which a certain size of tubing can maintain equal pressure. If the maximum run length is exceeded for a size of tubing, then the pressure supplied to each dripper or watering device will vary, and this can cause strange things to happen (e.g., water shooting out of drippers, no water coming out, etc.). Maximum run length varies for each size of tubing, so knowing how far you need to run tubing before ordering helps to make sure you get the right size for your project.
Total flow rate. Each size of tubing can only supply a certain number of gallons per hour before too much pressure loss begins to occur. To find the gallons per hour that you need in your system, you simply add up the output of all the watering devices. For example, if your system uses 40 .5-GPH drippers, 20 1-GPH drippers, and 2 adjustable drippers at 10 GPH, the total GPH used is: Add the total for each dripper type (20 + 20 + 20) to give a grand total of 60 GPH
40 x .5 GPH drippers = 20 GPH
20 x 1 GPH drippers = 20 GPH
2 x 10 GPH adjustable drippers = 20 GPH
Maximum Run Length & Maximum Gallons Per Hour (GPH)
Once you know both of these factors, then it is easy to select the size tubing that best fits your project needs. Take, for example, a project that has a maximum run length of 20 feet and a flow requirement of 60 GPH. What tubing could be used? Take a look at this chart. PLEASE NOTE this chart is in reference to your mainline:
You can see that the run length allows for all sizes of tubing to be used, but because the total GPH needed is 60, this eliminates ¼” tubing because 60 GPH is more than double what ¼” tubing can supply (30 GPH). If ¼” tubing were used for this system, it would not function properly.
Note: If you think you may want to expand your system in the future, it is a good idea to start with one tubing size larger than your run length and gallons per hour require, in order to give you the flexibility to add to your system in the future.
Dripline Types and Common Applications
Note: The maximum run lengths for the dripline still apply (¼” 30 feet & ½” 200 feet). Below is a chart of available driplines and common uses for each
Tubing Size | Maximum Run Length | Available Spacing & Emitter Combinations | Common Applications |
1/4" Dripline | 30 feet | Note: 6" spacing is recommended if the soil is sandy or plants are tightly planted next to one another |
|
1/2" Dripline | 200 feet |
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In conclusion, selecting the right tubing or piping for your drip irrigation project is crucial for ensuring efficient water delivery, optimal plant growth, and long-term success. By considering factors such as material, size, application, and system requirements, you can make informed decisions that maximize performance and minimize maintenance.
Whether you're designing a small-scale garden irrigation system or a large-scale farm operation, choosing the appropriate tubing or piping sets the foundation for a sustainable and productive irrigation solution.
Remember to consult with irrigation experts, consider manufacturer recommendations, and evaluate your specific needs to make the best choice for your drip irrigation project. With the right tubing or piping in place, you can enjoy the benefits of water-efficient irrigation and healthier, thriving plants for years to come.
Main article Article: DIY Drip Irrigation: Step by Step Guide
Best places to buy and save on Poly Tubing. Pls. note that measurements in most stores outside the US are in metric system.
