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Converting an Overhead Spray Irrigation System to Drip


Irrigation systems, included components and irrigating philosophies have come a long way in the past 20 years. While most systems still apply water overhead, as a growing population it’s become more imperative that we maximize every drop and start watering at a root level. The agriculture industry has been getting away from overhead sprinklers for years in exchange for a more conservative approach that uses emitter line and tape. With regulations as tight as they are on the West Coast landscapes of all shapes and sizes are now being asked to use drip irrigation whenever possible. To help water users make this decision water municipalities will even offer rebates to help subsidize the expense of retrofitting a landscape or irrigation system.

Understandably the task of converting your irrigation system from conventional overhead sprinklers to drip can sound overwhelming. Hopefully by understanding the components involved in a drip system you can be more informed when discussing options with your irrigation professional.

Pressure Regulation:

Typical irrigation systems apply water overhead using a series of pop-up sprinklers for shorter distances and rotors for longer distances. The water demand for each of these sprinklers is different and the rotors use substantially more water to irrigate larger areas of turf or slopes. Moving this much water takes a lot of pressure, usually around 55psi. A pop-up zone will need about 40psi to move water through the nozzle and onto the landscape.

A conversion to drip irrigation will not only use significantly less water but the pressure needed to run the zone only needs to be at 20psi. Lower pressures make a system easier to tinker with and assess different watering options, as every landscape is different.

With pressure in mind – you’ll need a pressure regulator for your drip system. An inline regulator will work and they are sold at most hardware stores or here at jainsusa.com. This regulator connects to the secondary side of your zone valve. At the controller nothing will change, you will however need to make adjustments to your Run Times to make sure the system runs a little longer.

Once the system’s pressure has been reduced you can connect fittings and tubing. A good rule of thumb is the tubing should get smaller the closer you get to the plant. For example, the supply tubing coming off your valve will be around ¾” or ½” in diameter - the tubing closer to the plant will only be ¼” or 1/8”, try to avoid going from small to big in diameter. This will help keep flows consistent throughout your systems emitter line and tubing. Lower pressures can lead to emitter clogging if a filter isn’t included on the system, be sure to use a filter on any zones that include drip emitters.

For groundcover and subsurface turf irrigation we keep our emitter spacing consistent as well. On average, emitter line will have 12” spaced emitters that distribute .5 or 1 gallon per hour. This will help apply water evenly across the span of your grid. Row spacing is typically 12” – 18” depending on soil density.

When we want to apply water directly to a plants root base and avoid root growth in between plants, we use a point source emitter. An example of a point source emitter is the Click Tif.

Point source emitters like the Click Tif pop into supply tubing creating a source for a predetermined amount of water. Color-coding will help identify the flow value of an emitter. After a point source emitter is connected you can rely on the water path directly out of the emitter or connect a ¼” tube to move water away from the emitter. A good point source emitter is pressure compensating, a term we use to describe the emitters effectiveness during pressure fluctuations.

Point source emitters like the Click Tif pop into supply tubing creating a source for a predetermined amount of water. Color-coding will help identify the flow value of an emitter. After a point source emitter is connected you can rely on the water path directly out of the emitter or connect a ¼” tube to move water away from the emitter. A good point source emitter is pressure compensating, a term we use to describe the emitters effectiveness during pressure fluctuations.

Larger tubing is used as a distribution source and connects to emitter line. There are two different sizes of emitter line, 17mm and ¼”. There are larger types available but for ease of explanation we’ll focus on 17mm and ¼”.

17mm emitter line is to be buried under groundcover or a couple inches below the soil. For esthetic purposes it’s better hidden and this helps keep the water closer to the root base, for longer. Pine needles, pine bark, cypress mulch, DG (decomposed granite) and rock are all popular means of covering a drip system.

For smaller applications and tighter plant spacing we use ¼” emitter line. ¼” emitter line or Mini-Pepline comes in 12” and 6” emitter spacing and comes with a .5 gph and 1gph flow option. Available in black and brown it’s easy to hide emitter line under soil and ground cover.

Both 17mm and ¼” emitter line will require landscape staples to secure tubing to the ground. Squeeze staples as you push them into the ground for maximum hold. Staples are designed to be installed pushed together and will expand once stapled into the ground, simply pushing them in with the forks open will not secure components and lead to trip hazards quickly.

Finally, there are fitting options to connect a drip irrigation system together. Power-Loc fittings provide a tight connection and lock to insure there are no late night blowouts. The PL-55 series of Power-Loc also fits 17mm emitter line and ½” supply tubing making the connection between supply line and emitter line easier with a single fitting.

All these components are available in our online web store and we have Technical Illustrations available to help provide a visual of how a system should be laid out.

If you likes this article and want to read more tips on proper landscape applications follow me @MDsSavesWater on Twitter and follow us @jainusa on Instagram.

Michael Derewenko

Hailing from Central Florida Michael Derewenko has been in the irrigation industry since age 15. Beginning his career working for his father’s large commercial landscape company Michael quickly learned the importance of irrigating landscapes efficiently and effectively. With a strong background in pumps, two-wire systems and irrigation design, there is not much in irrigation that Michael hasn’t encountered. Now operating in Southern California as a Territory Sales Manager with Jain Irrigation, Michael is applying his vast knowledge of conservation-based products and experience in product development to a region that is in dire need of water resource management.

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