Rain sensors are designed to shut off the irrigation system when it rains, and to keep it off for a certain amount of time. There are several types that are available, and it's important to place it in an appropriate location for the irrigation system.

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Rain Sensors Save Water

Rain sensors are designed to save water. They shut off after or during a rain event, and then they don’t allow the irrigation system to turn back on for a certain amount of time. There are two primary devices on the market.

The first is more popular, and probably more reliable. Within the housing unit are a series of discs. During a rainfall event, those discs absorb the water and cause an interruption of the irrigation system. The system shuts off and will not allow the system to come back on until the discs within the unit dry out. You can see the wire on this unit. It’s connected to the irrigation controller, and interrupts the controller, which stops the irrigation from coming on.

The other device that you may see is called a weighted device. It’s an open area in a small dish. After a certain amount of rain, the water weights it down and interrupts the irrigation system. It won’t allow it to turn on until all the water in the unit has evaporated. One of the main problems with this device is that you can get debris such as plant material and seeds. The debris will weigh the device down, and interrupt the irrigation system.

Another example is a wireless rain sensor, which is connected to the controller. The rain device is mounted to a gutter in a suitable location on your property. This is a disc type of device, and the unit is in communication with the clock. On these devices, it can be adjusted for the amount of rain that needs to enter before the system won’t turn on the irrigation system.

The location of the devices is very important, because either type will be influenced by certain conditions. It needs to be mounted in a location on a roof so that there’s no interference with the sprinkler system. If it’s in full sun, then both types will dry out faster, and the system will come on in a shorter period of time. However, if the irrigation system is in the shade, you don’t want to mount the device in full sun. So, it’s best to find a location that’s open and relatively homogeneous with the entire irrigation system.

This feature story prepared with Cathie Lavis, Kansas State University Research and Extension Professor of Landscape Management. For more information, visit your local county extension office or visit our website at KansasGreenYards.org.

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