How an irrigation solenoid valve works

The irrigation system has been a real innovation in agriculture, allowing more tasks to automate and optimize the time spent by the farmer. In addition, savings are generated in irrigation water by providing water only when the crop and the weather require it. In this area, an indispensable part of the irrigation head are the solenoid valves .

This article is focused on giving the importance that this fairly inexpensive device deserves that allows us to sectorize different areas that have different water needs. Its operation is very simple and it is not so common that they cause problems, although it will depend on the quality of the water and the impurities that it carries. However, as the electric valves are installed after the filter, except for slight clogs or wear of the membrane, they are inexpensive elements and guarantee many years of operation.

First of all, it is important to review all the articles dedicated to fertigation and automated irrigation. In this category you can find an extensive guide about it.


The irrigation solenoid valves are a fundamental part in an automated irrigation system , since they are the ones that close and give way to the water in the different pipes and sectors that can be installed.

Normally, they are formed by an electrical or hydraulic device that gives a signal to open and close the valve, driven by an automated control known as an irrigation programmer .

This system allows us to control the water outlet on a set schedule and time , so that our manual handling or being present is not necessary. At the same time, it also allows us to sectorize the cultivation area or the garden if we have several areas with differentiated water consumption.


The operating mechanism of the irrigation solenoid valves is really simple. In a normal state, the valve is closed and prevents the passage of water . When a small voltage is generated (generally, few volts are necessary for its operation), the solenoid that moves a magnetized core is activated and lifts the membrane, allowing the water to pass freely.

Logically, all this mechanism generates a slight loss of water pressure , but that is more than compensated by the functionality and independence that this device generates.

Therefore, it must practically be said that a programmer and an electrovalve are essential elements in any irrigation head, as are filters that prevent the passage of impurities through the valves and drippers.


The location of the solenoid valves always goes after the installation of the filter , to avoid possible plugging and damage to the membrane. They are usually placed either in the section after the pump drive or at the entrance of each irrigation sector, allowing the individualization of each one of them.


As we have mentioned, solenoid valves are simple devices to install and quite inexpensive compared to other parts of the irrigation head. In general, they are made up of the following elements:

  • Main casing:  usually made of plastic materials and with 2 inlets, connecting the inlet and outlet pipe by screwing.
  • The solenoid: one of the most important parts of the device, formed by a long cylinder or copper coil that carries current and activates the magnet that moves the membrane and lets water pass freely.
  • The cover: it is usually made of plastic and is screwed on by means of screws. The most modern solenoid valves include a manual system to control the water flow and also to activate it manually in the event of a power failure.
  • The valve: a plastic body that allows the passage of water when it is activated by the solenoid.
  • Membrane: formed by a flexible material that serves as a union between the cover and the valve body, being the element that generates the most problems according to the quality of the irrigation water.

Depending on the type of coil used in the solenoid, you will need an electrical pulse which can be either alternating current or direct current. There are those that can be activated with the energy of a cell or battery, in case of not having direct connection to the electrical supply.


There are several ways to classify an irrigation solenoid valve. Initially by its state before being activated, as is the following case:

  • Normally closed : when there is no power supply they are closed. These are commonly used in irrigation.
  • Normally open : they remain open when there is no power.

On the other hand, we can also differentiate them according to the electrical energy they need for their operation:

  • 9-12V DC latch:  its activation can be done by battery or batteries, especially in areas where there is no access to electrical energy.
  • 12-24V AC: they  are the most used today and are controlled by programmers that are connected to electrical power. They work with voltage of 220-230 V and alternating current, using between 12 and 24 V to activate the solenoid valves.


In general, for the world of agriculture and fertigation, there are very cheap and quite reliable solenoid valves . No special materials are required that increase their cost because water is a noble element, without viscosity and generally without impurities. And if not, we will have to review why the filter that we have installed does not work correctly.

If we are irrigating with well water that contains many impurities, we will look for a higher quality solenoid valve, since the element that usually has problems is the membrane. Likewise, the most important part would be to place a good filter before fitting the solenoid valves.

If we have access to electricity , the best thing to do is to use a 12-24 V type. They are the most common and reliable, and that reduces costs. If, on the other hand, we do not have access to electricity, we will look for alternatives with 9-12 V batteries.


Electronic equipment that is exposed to the elements outside often causes long-term failures. However, in the case of solenoid valves, we are talking about a fairly inexpensive device (there are complete elements for € 15), but some periodic maintenance may come.


One of the most common failures in solenoid valves is that, being closed by the programmer, it continues to let water through. In this case, the problem may be due to the solenoid (electronic device) or to the membrane or valve that allows the water to pass through.

  • If when activating the programmer, we hear an initial hum, in principle the solenoid works correctly.
  • If we do not listen to it, it is likely that the solenoid has broken and we will have to replace this part, not being necessary to change the entire solenoid valve.

If everything works correctly, it is most likely that the membrane has accumulated dirt and does not close well, so we will have to disassemble the case with the screws on the top and clean it.

In the event that after this operation the water continues to flow through, despite not being activated, the most advisable thing is to completely replace the irrigation solenoid valve.


A solenoid valve exposed to the sun loses its plastic elasticity and causes it to crack easily. This causes that, over the years, it loses a small amount of water constantly. In this case, it is advisable to replace the piece with a new one and protect it from the Sun by means of a watering house or, at least, with protective plastic.

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