About: I am 47 years old and I live in Brazil. I am a Telecommunication / Electronics Engineer. twenty years acting in the industry of "Telecommunication and Networking". I like everything that engages Te...

I is a simple system, using Arduino to automate the irrigation and watering of small potted plants or crops.
This system does the control of soil moisture, doing indications via LEDs and in case of dry soil emitting a alarm beep. In case of dry soil it will activate the irrigation system pumping water for watering plants.
The system uses a LCD display to notify all actions that are taking place and a real time clock.
The Theory (from Wikipedia):
Water content or moisture content is the quantity of water contained in a material, such as soil (called soil moisture), rock, ceramics, fruit, or wood. Water content is used in a wide range of scientific and technical areas, and is expressed as a ratio, which can range from 0 (completely dry) to the value of the materials' porosity at saturation. It can be given on a volumetric or mass (gravimetric) basis.
Volumetric water content, θ, is defined mathematically as:

where  is the volume of water and  is the total volume (that is soil volume + water volume + air space).
Gravimetric water content[1] is expressed by mass (weight) as follows:

where  is the mass of water and  is the bulk mass. The bulk mass is taken as the total mass, except for geotechnical and soil science applications where oven-dried soil (, see the diagram) is conventionally used as .
To convert gravimetric water content to volumetric water, multiply the gravimetric water content by the bulk specific gravity of the material.
In soil mechanics and petroleum engineering, the term water saturation or degree of saturation,  is used, defined as

where  is the porosity and  is the volume of void or pore space. Values of Sw can range from 0 (dry) to 1 (saturated). In reality, Sw never reaches 0 or 1 - these are idealizations for engineering use.
The normalized water content, , (also called effective saturation or ) is a dimensionless value defined by van Genuchten[2] as:

where  is the volumetric water content;  is the residual water content, defined as the water content for which the gradient  becomes zero; and,  is the saturated water content, which is equivalent to porosity, .


To accomplish this project, you will need:

1 x Arduino UNO MEGA Duemilanove or Teensy 2.0 +
1 x LCD display with I2C communication
1 x RTC module with I2C communication
1 x Relay Module opto-coupled to 250V/10A
2 x Modules "Driver" LM-393 general purpose
1 x Soil Moisture Sensor (Hygrometer) KDQ11
1 x Water Level Sensor (Homemade)
1 x Buzzer piezoelectric
2 x LEDs - 10mm, Green
1 x LED - 10mm, Red
1 x LED - 10mm, Yellow
4 x Resistors 150 Ohm 1/4 W
1 x Water pump for aquarium, with filter system (127 or 220V)
1 x Electric Power Cable, 127/220VAC - 10Amps
1 x Socket 127/220VAC - 10 Amps
Wires and cables for connections and communication

You can purchase the soil moisture sensor and  "Driver" on ebay.

You can purchase the soil moisture sensor and  "Driver" on ebay.


In the Pictures you have an overview of the components used.

Data from the soil moisture sensor set:
When the soil is dry, the impedance will be high and the LM-393 will show a high value on the output.
When the soil is wet, it will show a low value in the output.
The 3 LEDs range can be defined as:
- Soggy soil -  moisture between 0 and 500;
- Wet soil - moisture between 500 and 800;
- Dry soil - moisture between 800-1023;
The module has one digital output and an analog output. (in the project, should be used to analog output)

The water level sensor:
This sensor must be made (homemade) on phenolite board, with spacings of 1 mm between trails and trails with 1 mm of thickness.


Below you have:
1 - a block diagram;
2 - an interconnection diagram (in manuscript);
3 - a wiring diagram;
4 – usability principles

These diagrams are describing the main system interconnections.

You can get the original of this file by accessing the "GOOGLE driver" below:





Please, fix an error in your "interconnection diagram (in manuscript)" diagram:
The level sensor must be connected to pin A0 of Arduino and the soil moisture sensor must be connected to pin A1 of arduino.

Description of the main connections:
RTC <-> Arduino:
+5 V <-> +5 V
SDA <-> A4
SCL <-> A5

Relay <-> Arduino:
+5 V <-> +5 V
IN <-> D7

LCD <-> Arduino:
+5 V <-> +5 V
SDA <-> A4
SCL <-> A5

BUZZER <-> Arduino:
+ <-> D2
- <-> GND

LM-393 DRIVER (moisture sensor) <-> Arduino
+5 V <-> +5 V
OUT <-> A1

LM-393 DRIVER (water sensor level) <-> Arduino
+5 V <-> +5 V
OUT <-> A0

Other Components <-> Function <-> Arduino
Red LED <-> Dry soil <-> D5
Yellow LED <-> Soggy soil <-> D3
Green LED <-> Moist soil <-> D4
Green LED <-> Water Pump <-> D6


You can download freely the code for this project in the "GOOGLE driver":

Or on the GitHub:

Arduino Watering System Files

Any problems, questions and suggestions, please send an email to:



Below is a picture with an example of how the system works and how the tests should be performed.
Logically, as the system has an hour  pre set to operate, you can change the time via software for the time you will do the tests, and after you can adjust the operational "time".


Questions and suggestions send to: arduinobymyself@gmail.com

Part 1:


Part 3:


3 People Made This Project!


  • Water Contest

    Water Contest
  • Clocks Contest

    Clocks Contest
  • Creative Misuse Contest

    Creative Misuse Contest

264 Discussions

Hi! The project it´s amazing! Do you now if I could do it with a Real Clock Time Module with 5 pins (vcd, gnd, clock, data, rset)? that was the only module that I could find easily.

I would like to know the connection to a0, it is for potentiometer or moisture sensor?

Thank you very much!


6 months ago

Good day sir ,can i please have the code for your awesome project. i love your project and the system looks very good . my email is ahmad.kargar@yahoo.com


6 months ago

Good day sir ,can i please have the code for your awesome project. i love your project and the system looks very good . my email is ahmad.kargar@yahoo.com


6 months ago

Good day sir ,can i please have the code for your awesome project. i love your project and the system looks very good . my email is Ahmad.kargar@yahoo.com

Dear Sir you did awesome innovative work. I here would like to use this for maize research program. Could I please contact you through my email ID: shivakumarjha@yahoo.com if can please let me know your email so that I can take helpful suggestion from you. Thanking you

HI can you send me the code to my email : ivananievas@yahoo.com

Hi, I wanted to know which relay you used in this product ? thanks

Good day sir. Your project was awesome. Were planning to build our own watering system for our project in instrumentation . Please sir. Send the code in my email "kennethmillan06@gmail.com" i hope you can help us sir. Its our pleassure sir. Thank you

Helo sir . Your project was awesome . And were planning to build our own for our project in instrumentation . I hope u can send me the code to my email " kennethmillan06@gmail.com ". Thank you sir.

Nice project. I'm studying about same project. Could you send me the Schematic and code ardruino via email : nguyenthimaianh1202@gmail.com. Thanks you very much!!! Hope you send me soon


2 years ago

hello....in my watering system project...i have a problem regarding to the lcd display come out weird character when i connect ac source water pump into the cct arduino...

what is the problem actually???

hope u can help me....plesaseeeee...

1 reply

my screen showed crazy characters and sometimes even Arduino hanged immediately after relay works, according to this post(https://electronics.stackexchange.com/questions/237688/arduino-16x2-lcd-weird-symbols-after-relay-switch/330632#330632) and some other websites I found it is something about the AC device because when the device was disconnected the relay and other parts would work properly but when the AC device which is a simple Aquarium water pump was connected to test the system in real situation, after relay changes (on and off both), the system goes crazy, I put 6 * 1nF capacitor in parallel (5.6nF totally) to entire system close to the relay between VCC and Gnd of Relay and just one n4148 diode to VCC wire, this diode shows around 110 K resistance with Multimeter. therefore, in any case if there is any back current or emf or Idk anything to interrupt the system, it prevents them all.

thanks to you all for sharing information. hope this helps somebody.


10 months ago

hi i made your project but the rtc doesn't work

where do i fixing the date and time for the first time ,please

because when the arduino is on date and time is 165:165:2165


thx fas83

Hi!! The project is really nice. I have a problem with Arduino board coding. I made it with the same components and coding which you were given above(Git Hub). But finally, when I going to upload the programme there was an error in compiling.I have not enough knowledge with coding.The error is attached below.I really appreciate if you could support me to resolve the problem.

Thank you.

Capture 1.PNGCapture 2.PNGCapture.PNG


It's written 1 x RTC module with I2C communication in the components list while your picture shows RTC DS1302 which is not I2C. How did you make it works ?Thanks!


1 year ago

Your project really interesting. i'll try to make for mine too. i hope can u send me the code adruino,library and simulation for proteus for me too..

i begging you, sir

my email:
as soon as possible, sir
thank you very much, sir

Can i get your code , pls help me sir..

antonio.bartolic@gmail.com pls send to here

Any one tried to make watering system with public supply water flow type? I mean where you need valves to stop or start water flow? If anyone building similiar Project, can free to contact me at milukasm@gmail.com