Drip Irrigation: The Devil’s in the Details

Brad Wier

When properly designed, drip can be the most efficient method of irrigation. But when installed incorrectly, drip can use as much water as ordinary sprinklers, if not more.

When properly designed, drip can be the most efficient method of irrigation, delivering a steady stream of moisture directly into the roots of plants without the evaporation that occurs with sprays, rotors and sprinklers.

But you’d be surprised how much water this technology can waste when poorly designed and scheduled. there are plenty of ways to install it wrong: from bizarre piles of overlapping, tangled drip tubes to lines spaced too close together to lines arranged in rigid geometric patterns where nothing is growing.

Even without the evaporation, poorly designed drip systems can use as much water as ordinary sprinklers. And when it’s functioning properly, it’s hard to see the water with drip — no visual cue when it’s running, or when it’s leaking. Many irrigators use colorful pop-up indicators so customers can see when their drip lines are pressurized. SAWS requires these pop-up indicators.

Still, many of the issues with drip come not from design but from scheduling. Drip runs longer than other irrigation types — 45-60-minute run times are not uncommon — so any leaks are magnified over a long run cycle. What the pictures can’t show is that many of the featured drip systems were set to water every day. Remember, the whole purpose of drip irrigation is to provide, one to two weeks’ worth of waterSo there is never a need to run it more than once a week.

When properly designed and programmed, drip is one of the most efficient methods of irrigation. Just remember to familiarize yourself with the system. It’s not a bad idea to walk through it while it’s running. SAWS Conservation offers irrigation audits — just call 704-SAVE (7283) or email us to schedule a consult.

Ideal Drip Irrigation with Inline Tubes
Tubes 0.6 gallons per hour, 18 inches between emitters
Spacing 18 inches between tubes
Water ½ inch per week
Precipitation 0.43 inches per hour
Run Time 60 minutes

Examples of Bad Drip Design

1. A concrete lamp post needs no irrigation at all. In this case the extra tubing could have easily been left out.
2. Decomposed granite does not grow either.
3. Empty landscape beds don’t need water either, extra tubing just creates more opportunities for leaks like this.
4. In-line drip tubing emits water out of regularly spaced emitters. Obviously, it should only be used where plants are growing.
5. Entirely wrong location and amount of drip tubes for a tree.
6. These drip lines have been spaced at 6-inch intervals. Properly spaced drip lines should be laid at 18- or 24-inch intervals.
7. Running drip too long will inevitably drown plants.
8. Entire landscape of native plants was drowned by excessive drip irrigation.
9. Proper 24-inch spacing.
10. What’s the proper spacing of drip in areas without plants? None. Areas void of plants don’t need irrigation. Period.

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