Before designing an irrigation system the following parameters have to be taken into consideration:


1.- Flow rate:

It is the volume of water that passes through a pipe in a certain period of time.


2.- Pressure:

Weight of a water column over a surface. 1 bar = 1 kg/cm2 = 10 m.w.h.


3.- Pressure loss:

Pressure losses are caused by turbulences due to friction of the water against the walls of pipe and fittings.


4.- ETP:

It is the quantity of water lost by evaporation from a regular vegetal cover. Irrigation should compensate ETP. Factors that interfere with ETP:




Wind speed

Solar Radiation.


5.- Type of soil:

Type of soil give us the input about the level of water retention.

Sandy soil: Very reduced water retention (more start-up’s with less irrigation time).

Medium or low clay soils (average/medium): Normal start up’s (normal irrigation time).

Clay soil, compact: Fluids easily (less start up’s with less irrigation time).


6.- Vegetation Type:

Important to know plant needs in water: Grass, trees, shrubs, plants…

Important to know the size of growing plants.


7.- Inclined terrains:

In inclined terrains we will get pressure loss and soil erosion.

All inclined sectors should have sprinklers or sprays (head’s equipped with check valves).


Once we have all this information, we need to draw the irrigation area with maximum details as possible, including points of water and electricity source.


You can ask to your architect or consultant for the drawings of the specific area to irrigate. With the drawings properly detailed, Watertech Ltd. will be able to design the best irrigation equipment accordingly.




If we have areas with ranges less than 5 meters, we should use Sprays-Heads

If we have areas with ranges over 5 meters, we should use Sprinklers.

If we have trees, shrubs or plants, we can use drip or low volume irrigation.


All devices have a certain range capacity, for this reason, in order to guarantee that all devices apply the same quantity of water; we just need to adjust the irrigation time to their performance and never mix them together in the same sector of our irrigation system.


Each device has its flow rate, which depends on the angle (90°, 180°, 270°, 360°).

Sometimes it is necessary to change the nozzle, in order to guarantee that device irrigates angles of 180°, applying the same quantity of water as the ones at 90°.

As the area of 180° is the double than the area of 90°, the nozzle has to have a double flow rate as well, to ensure the same quantity of water.




After dividing the irrigation area in sectors and determining the devices and flow rates, we need to work out the pipe sizing:

We need to know the flow rate passing in the pipe, based on all the devices required in this line.

We need to know the pressure required for the devices in the line.

We need to know the pressure loss generated by the electric valves and length of the pipe.

There are some tables and programs that calculate the diameter of the pipe according to the flow rate and the pressure required for the installation.


Let Watertech Ltd. calculate the best irrigation system for you. We use the latest technologies to design, calculate and select the best products for you to be proud of your garden.

Watertech Ltd 2015 ®. Developed by Wicre8 Ltd