What is the "Real" GPH for Emitter Tubing

You’re right; 80 in/hr is 'way high. We’ll assume you’ve not confused emitter specs of GPH with typical irrigation flow rate calculations from GPM. If you can isolate water delivery through your home water meter, calibrate that whole drip zone together to see what’s really happening:

o Learn how your water meter dial works - if it has hands, how many gallons is one revolution? (Mine is 10 gallons per revolution, plus numeric wheels, yours might be different). Determine the total area you expect to be irrigated in the zone in square feet, perhaps with this:

o Find a stopwatch to do some timing. Your phone is likely to have one.

o With the zone running, watch the meter dial and start the stopwatch when the hand reaches the zero or top dead center position or zero last digit, whatever works.

o When the hand has gone around at least twice, stop the stopwatch when the hand hits top dead center again.

o Stop the zone and do some math (we’ll pretend you did 20 gallons by the meter in 4.5 minutes by the stopwatch for an irrigation zone of 500 sq. ft.):

  • Flow is 20 gallons in 4.5 minutes, or 20 / 4.5, or 4.4 GPM.
  • Precipitation Rate (Nozzle Inches Per Hour) is 96.25 x flow (4.4 GPM) / area (500 sq ft), or 0.847 in./hr.

Probably can’t get much better than that… no catch cups, no guessing, no matter what the published emitter rates are you know how much water is applied over time to the zone.

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