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How to Determine Gallons of Water Per Hour Needed for a Plant Drip System

By Jack S. Waverly ; Updated September 21, 2017
Drip irrigation requires knowing the correct amount of water to use with the system.
Drip.. image by Matt Ferrell from <a href='http://www.fotolia.com'>Fotolia.com</a>

When you are planning to install a drip irrigation system, you must use the correct emitters to deliver water to the vegetation. To determine the correct emitters, you need to know the water pressure per hour, expressed as gallons of water per hour (gph). To determine the correct gph, there are simple calculations you can do.

Select a bucket to measure water in. Find out how many gallons of water the bucket will hold. This should be listed on the side or underneath of the bucket.

Put the bucket underneath a water spigot so water can flow freely from the spigot into the bucket.

Open the spigot all the way so the water runs full force. Use a timer to count 30 seconds. Turn off the water. Observe the level of the water to determine the amount of water in the bucket. For example, using a 5-gallon bucket, if you filled the bucket half way, you have 2 1/2 gallons. Convert this to decimals to calculate (2.5 gallons).

Use the calculator to divide 60 minutes (1 hour) by 30 seconds; this would be 60 divided by 30 to equal 2.

Multiply the gallons of water collected in Step 3 by the result of the calculation in Step 4. Using the example provided, this would be 2.5 gallons multiplied by 2 (2.5 x 2 = 5).

Multiply 60 minutes by the total from Step 5. This will give you the total gallons per hour for the water. Using the example, you would multiply 60 by 5 to get a total of 300. This means you need emitters that can operate with a water pressure rate of 300 gph for your drip irrigation system.


Things You Will Need

  • Bucket
  • Timer
  • Water source
  • Pencil and paper
  • Calculator