rain water  sensor or rain switch is a switching device activated by rainfall. There are two main applications for rain sensors. The first is a water conservation device connected to an automatic irrigation system that causes the system to shut down in the event of rainfall. The second is a device used to protect the interior of an automobile from rain and to support the automatic mode of windscreen wipers. An additional application in professional satellite communications antennas is to trigger a rain blower on the aperture of the antenna feed, to remove water droplets from the mylar cover that keeps the pressurized and dry air inside the waveguides.


Rain  water sensors for irrigation systems are available in both wireless and hard-wired versions, most employing hygroscopic disks that swell in the presence of rain and shrink back down again as they dry out — an electrical switch is, in turn, depressed or released by the hygroscopic disk stack, and the rate of drying is typically adjusted by controlling the ventilation reaching the stack. However, some electrical type sensors are also marketed that use tipping bucket or conductance type probes to measure rainfall. Wireless and wired versions both use similar mechanisms to temporarily suspend watering by the irrigation controller — specifically, they are connected to the irrigation controller’s sensor terminals or are installed in series with the solenoid valve common circuit such that they prevent the opening of any valves when rain has been sensed.


  • A rain water  sensor is used to build an automatic on/off wiper.

Rain Sensor Use

  • It is used in a smart irrigation system.
  • It is also used as an irrigation monitoring quadcopter.


Rain Sensor


If the D0-LED does not light up check the following:

  • Is the module hooked up properly?
  • Sometimes salinity is an issue with these units, this one worked fine with filtered, bottled water, but in some instances, you may have to add a bit of salt to increase the waters conduction.
  • This might be a bit more tricky, but for some reason, two different models by two different manufacturers have had defects in their soldering skills. Make sure all of the little SMD’s and connectors have been soldered on properly. IE – are solder joints actually soldered?
  • If none of the previous makes the D0-LED light up, your sensor may be defective.


  • Working Voltage: 5V
  • Output: Digital and Analog
  • A0… Analog outputD0……… Digital outputGND….. GroundVCC…… Positive voltage (input: 5v for analog 3.3v for Digital).
  • Indicator LEDs: Power and Output Indicator
  • Loop Pins:+ ………. Sensor board hookup A– ………. Sensor board hookup B

    Materials To Be Required:

  • Rain Water Sensor
  • Arduino
  • Jumper Wire
  • Bread Board


Rain Sensor …………….. Arduino
VCC…………………………. 5v
GND………………………… GND
A0……………………………. Analog in 0


Inspired From:

A Rajasthan village now no longer depends on a trickling government water supply—it meets its demand through water harvesting and has become a role model for other villages.

All the 145 houses in Jhunjhunu’s Ismailpur village have built a 13-foot-deep underground tank which can store 20,000 litres of rainwater. The tank is charged with rooftop water during the monsoon through pipes. Every member of a family of six (average size) uses his share of eight litres per day with a self-discipline which helps the family keep the stock going till the next monsoon.