Sub Surface Turf Irrigation Drip Zone Planning

Sub Surface Turf Irrigation Drip Zone Planning

Planning Your Drip Line Layout

Planning a Sub Surface Turf Irrigation System is not much different from planning any Drip Irrigation System.  The basic planning is the same and necessary to get the most out of your system.

Step 1: Put It On Paper!: You don't have to be an artist for this part but some graph paper will usually help you out.  Draw out the turf area with as much general detail as possible with regards to distances, structures, and water source location.  The following is a critical list of information for your system:

  • Water Source and Distance from Water Source to the start of the Drip System
  • Number of Rows and Length of Rows (to calculate total drip line required).  
  • Distance Between Rows (assume 12")
  • Number fo Emitters and Total Water Requirements

This is the basic information needed to get started. 

Water Source

As with all Drip Irrigation Systems one of the most important components of information needed is your Water Source capacity and pressure.  The amount of water and pressure you have available is critical to the design of the sub surface system   The flow rate and pressure available will help to determine how many rows you can water at any one time and how many zones you may require.  The following information will assume an existing water supply with set or municipal pressure. 

Flow Rate: The easiest and most tried and true method for measuring your flow rate is the 5 gallon bucket method.  Simply fill a 5 gallon (19 Litre) bucket with your outdoor faucet or water outlet and record the time it takes to fill.  You can then calculate the flow rate based on your results.  The following is an example.

Example 1: 45 Seconds to Fill: To Calculate the flow rate you divide 60 Seconds by 45 Seconds and Multiply by 5.

Flow Rate = 60 / 45 x 5 = 6.67 Gallons Per Minute or 400 Gallons Per Hour ( 60 Minutes x 6.67 Gallons Per Minute )

Example 2: 90 Seconds To Fill:

Flow Rate = 60 / 90 x 5 = 3.33 Gallons Per Minute (GPM) or 200 Gallons Per Hour (GPH)

Pressure: Calculating pressure requires the use of a pressure gauge or an approximation of municipal pressure.  If using a pump, you may be able to dictate pressure precisely.  Pressure decrease over distance travelled in all tubing materials and the decrease increases as the size of your tubing decreases.  In addition to the static pressure loss there may also be dynamic pressure loss which is the pressure lost from emitter output down the drip line.  Below is a basic chart of pressure loss for both Poly and PVC tubing.

Poly Tubing Max. Flow GPM (GPH) PSI Loss/100ft Sch 40 PVC Max. Flow GPM (GPH) PSI Loss/100ft
1/2" 4.6 (276) 8.8 1/2" 4.6 (276) 7.7
3/4" 8.2 (492) 6.3 3/4" 8.2 (492) 5.6
1" 13.4 (804) 4.8 1" 13.4 (804) 4.2
1 1/4" 23 (1380) 3.1 1 1/4" 23 (1380) 3.1
1 1/2" 33.8 (2028) 2.9 1 1/2" 33.8 (2028) 2.9
2" 52.3 (3138) 1.9 2" 52.3 (3138) 1.9

As most Drip Emitters and Drip Emitter Tubing operate between 10 to 60 psi there is usually a wide range to work with but pressure loss must be considered, especially if travelling a long distance between the water source and the start of your Sub Surface Drip Irrigation System. The general rule of thumb is to start bigger to avoid pressure loss issues.

You are now ready to apply this information to your Sub Surface Watering System.

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