Garden Tidbits - Expert Advice for the Garden and Landscape

In-Line Drip Irrigation

Using in-line drip irrigation tubing is the most elegant system to install. Simple roll out the tubiing , flush and cap. No arm twisting, hand stressed punching in of emitters.    When you first price the tubing, you might think it is expensive. But it is actually about half the cost of punched in emitters and the solid tubing. In 2011 pricing, a 100-foot roll of in-line tubing with 1/2-gph emitters (pressure compensating for the most even water distribution) installed every foot costs about $32. A 100-foot roll of solid one-half-inch tubing cost is around $17. One hundred punched emitters (also with pressure-compensating emitters) costs $44 dollars. So, in-line equals $34, while punched-in emitters equals $61! (That’s one reason the irrigation stores push punched-in emitters so much.)   

drip irrigation

The internal emitters utilize what is known  as a “tortuous path” the water must pass through a labyrinth of right-angled channels inside the emitter before  exiting via a hole much larger than that of a typical  punched-in emitter. The tortuous path causes the water to form a continuous vortex, a kind of  horizontal tornado, which keeps any sediment,  sand or silt in suspension so it won’t settle out and clog the emitter.  I used in-line emitters for Chester Aaron’s 60 raised beds of garlic 25 years  ago. Even with well water full of iron oxide [notorious  for clogging regular punched-in emitters],  I’ve found only a few clogged emitters in a thousand  feet of tubing.  Another person I know actually took off the  filter and pressure regulator for four years and  found no clogged emitters compared to the filter  and pressure regulator assembly they originally  installed. A true testimony to the cleaning action  of these emitters.

irrigation emitter

The emitters come pre-installed  in tubing with 12-, 18-, 24-, and 48-inch spacings  [they can be custom ordered at just about any interval—  for an extra fee], but the type most commonly  sold to gardeners is the 12-inch interval.  The emitters inside the hose are rated to dispense  either 1/2- or 1-gph [actually 0.6 and 0.92 gph].  The cost ranges from $22 to $32 for a 100-foot  roll depending on the emitter [its flow rate and  whether or not it’s pressure compensating.]  Newer versions include tubing with pressurecompensating  emitters at the same intervals  as in the noncompensating in-line tubing and  with 1/2- or 1-gph flow rates. [See the photo of the exposed red pressure-compensating emitter in the tubing.] I  always use the kind with 1/2-gph emitters on 12-  inch centers because they will irrigate, depending  upon how long the system is left on, both sandy  and clayey soils.  The benefits of in-line pressure-compensating  emitters are: they are very easy to install, simple  to snake around your existing plantings, suffer  less clogging than porous tubing and some  punched-in emitters, provide consistent rates of  irrigation without regard to slope or length, have  no external parts to snap off, their connectors  or fittings don’t leak, and the connectors, either  compression fittings or Spin-Loc™ fittings, seal  better than metal hose clamps with porous hose

Much of this  “newer” technology is available from suppliers  to the commercial landscape trade. [See your local Yellow  Pages.]   



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