Dripline, Soaker Hose and Soaker Tape
by Stuart Spaulding —
CLIA Certified Landscape Irrigation Auditor Training & Communications Manager at DIG Corp.
Porous Soaker Hose, Soaker Tape, ¼” Dripline, ½” In-line Emitter Tubing
If I were limited to a single suggestion to make to those who are planning and installing drip irrigation systems, it would be this: Keep it simple!
Thankfully there are some drip irrigation products available now that make it easier to accomplish this goal- Soaker Tubing. These products come in several types and sizes, but they are all designed to do one thing- to irrigate the soil and plants directly under and adjacent to the tubing. This common characteristic makes these products a wise choice to irrigate trees, row crops, vegetable and flower beds, containers, and any densely planted area where total saturation is required. Each type has unique features and benefits, pros and cons; some are suitable for long runs, some are not. Some are suitable for sub-surface installation, and some are not. In the following paragraphs, I will describe these products in detail, in the hope that this information will enable you to choose the right product for the site and ensure long-term success with your irrigation and landscape project.
Porous Soaker Hose
Porous soaker hose is a “do-it yourself” group of soaker type products that have been available in the big box retailers for many years now. The tubing is produced in ¼”, 3/8” and 5/8” diameters, and is typically made from a blend of recycled rubber and polyethylene however some manufacturers use a synthetic fabric-like material. The product contains no drip emitters, the water weeps or sweats out of tiny holes in the tubing wall at a rate of approximately ½ gallon per hour per foot. This characteristic makes it a good choice to utilize in light, sandy soils.
The product is non- pressure compensating, which means that the flow rate will decrease with lower pressure and increase with higher pressure, and it should be operated between 10 and 25 psi. It is not suitable to be installed below the soil surface, but it can be placed on grade & covered with a layer of mulch to keep it protected and out of sight. The ¼” variety is the most common size, which is a good choice to irrigate plants in containers or flower boxes, which typically are filled with fast draining sandy soil. ¼” porous soaker hose uses ¼” barbed fittings to connect to ¼” micro-tubing or ½” poly tubing. The larger sizes are usually sold in kits that connect to a standard outdoor faucet. Regardless of the size, the tiny holes are more susceptible to clogging than point-source emitters, so it is recommended to install a minimum 155 mesh screen filter upstream of the hose to keep it from clogging up over time. The soaker hose has a short bending radius and will not kink if installed in a circular or spiral pattern.
Drip Soaker tape is another low-volume soaker type product that is not new. It has been used by farmers and growers for quite some time now, because it is inexpensive, efficient, and has a relatively long maximum run length.
Soaker Tape remains flat until pressurized with water
The product is a flat, thin walled polyethylene material, which usually has non- pressure compensating, low flow emitters built in to the wall every 12 inches. It can be run well over 200 feet and still achieve good distribution uniformity, but it needs to be installed in relatively straight runs. This makes the product a good choice to irrigate row crops like corn, and other food crops that are closely planted. Most of these products use special fittings with a locking ring, and adapters are readily available so the “tape” can be easily connected to PVC pipe, poly tubing, or a garden hose. Like all the soaker products in this category, for best results and long- term success, the soaker tape should be operated between 10 and 25 psi. and protected by installing a 155 mesh filter after the valve and upstream of the soaker tape.
Quarter inch drip line is a type of soaker tubing that many people may not be aware of. It is ¼” micro- tubing that has low flow non-PC emitters built in to the tubing wall every 6, 9 or 12 inches. The flexible, durable dripline is very versatile and is an excellent choice to irrigate vegetable beds, trees, plants in flower boxes and containers, densely planted flower beds, and ground covers. The built-in emitters have a large labyrinth flow- path so the product is much less prone to clogging than the porous soaker hose, and it is more resistant to damage due to chemicals and fertilizers as well. The tubing is extruded from polyethylene resin with UV inhibitors added so it will last a very long time even if installed on the soil surface.
¼” dripline is sold in black or brown colors and several different emitter spacing & flow rates
The ¼” dripline is often sold in kits that usually start from an outdoor faucet, but the coils are also available separately and can be easily connected to ½” poly tubing, multi-outlet drip manifolds, or PVC pipe. The dripline should be operated at reduced pressure (10 to 25 psi) and it can be installed on the soil surface or covered with a layer of mulch to maximize water savings.
½” Pressure Compensating Dripline
Half inch PC dripline is made by many companies and is known by many names… in-line emitter tubing, ½” dripper-line, ½” emitter line, to name just a few. It is basically ½” poly tubing with pressure compensating low-flow emitters factory installed at equidistant pre-set spacings “built- in” to the tubing wall. It is similar to the ¼” drip line with a few major differences. The first major difference is the diameter of the tubing. The ½” dripline has a much larger inside diameter than the ¼” drip line. The second major difference are the emitters; the designs vary by manufacturer, but they are all pressure compensating (PC), which means that the prescribed flow rate of each emitter will remain constant regardless of pressure fluctuations due to changes in elevation or head loss along the line.
The PC dripline manufacturers have dedicated significant resources to develop and manufacture these products, and especially to the design of the PC emitters. ½” PC drip line is the only one of all the products in this category that is suitable for sub-surface irrigation of turf areas, and manufacturers have employed different designs and methods to prevent root intrusion which was once a major cause of emitter clogging in sub-surface drip irrigation systems. Some manufacturers’ designs include physical barriers like check valves, which not only work to prevent root intrusion, they also improve system uniformity and conserve water by preventing water from draining out of emitters after the system valve closes. Others impregnate each emitter with non-toxic preemergent chemicals to divert root growth. Another major manufacturer incorporates a thin copper “shield” in each emitter to prevent and reduce root intrusion. All these technical advancements have greatly improved the performance of PC dripline and most manufacturers now include product warranties that cover root intrusion for 5 to 7 years.
So, if you are looking for the most advanced, longest lasting soaker product, one that can be run for long distances and achieve excellent uniformity, PC dripline should be at the top of your list. Even though the emitters are self-flushing and pressure compensating, it is still highly recommended to install a filter and a pressure regulator upstream to ensure long term success. The products are available in several different flow rates, making them suitable for a variety of soil types. PC dripline is an excellent choice to irrigate turf or plants in narrow or oddly shaped areas, and the product can be installed on or below the soil surface.