Drip tape is a low-flow irrigation method used in agriculture and horticulture. It is a thin-walled, flexible polyethylene tubing that delivers water directly to the root zone of plants, minimizing water loss from evaporation and runoff. This slow, measured application of water maintains optimal soil moisture for plant growth. This delivery method is highly effective for water conservation, often achieving water use efficiency rates as high as 95%.
Physical Structure and Components
Drip tape differs from rigid drip lines due to its thin-walled construction, typically made from polyethylene resin. Wall thickness is measured in ‘mil,’ ranging from 5 mil for single-season use up to 25 mil for multi-year crops. This thin structure allows the tape to be manufactured and stored flat in large rolls, expanding into a round tube only when pressurized with water.
The tape incorporates built-in water outlets known as emitters, spaced at precise intervals (e.g., 6, 12, or 18 inches) depending on the crop. These integrated emitters include a specialized internal pathway, often called a labyrinth or turbulent flow channel. This flow path is a complex, maze-like series of small channels. The tape is available in various diameters, such as 5/8 inch or 7/8 inch, to accommodate different row lengths and flow requirements.
The Operational Mechanism of Water Delivery
The drip tape relies on hydraulic principles to transform high-pressure water into a slow, uniform drip. Systems operate at a low pressure, typically 8 to 15 pounds per square inch (PSI). This low operating pressure is necessary because the thin walls of the tape cannot withstand the higher pressures of conventional irrigation systems.
When water enters the tape, it is forced through the labyrinth flow path within each emitter. This long, narrow channel increases resistance and friction, effectively dissipating the incoming pressure. By the time the water reaches the exit hole, its pressure is drastically reduced, allowing it to exit as a slow, controlled drip. The turbulent flow within the labyrinth also helps reduce the risk of clogging by keeping small particles suspended.
This process results in a consistent, low flow rate from each emitter, measured in fractions of a gallon per hour (GPH). This steady application creates a localized wetting pattern, ensuring plant roots receive continuous moisture. Precise flow regulation across the entire length of the tape ensures uniformity in water distribution, which is essential for consistent crop yields.
System Setup and Essential Accessories
To create a functional drip tape system, several peripheral components are required. The primary accessory is the filtration system, which removes debris, sediment, and organic materials from the water. Since emitter pathways are fine, even tiny particles can cause blockage, making a screen or disc filter (often rated for 150 mesh or 80 microns) necessary for system longevity.
A pressure regulator must be installed after the filter to reduce the high source pressure to the tape’s low operating pressure (8 to 15 PSI). Without this regulator, high pressure would cause the thin-walled tape to burst or result in inconsistent flow rates. Specialized fittings are then used to connect the pressurized mainline tubing to the drip tape itself.
These specialized components include couplers to join sections of tape and take-offs to connect the tape to the main supply line. End caps or flush valves terminate each run. The flush valve allows the user to periodically open the line to flush out accumulated sediment or debris. A backflow preventer is also installed near the water source to protect the main supply from contamination, especially when fertilizers are injected into the system.