Self Watering Soda Cans With Electronic Water Meter




Introduction: Self Watering Soda Cans With Electronic Water Meter

I'm very bad at caring for plants, and I've always wanted to have some edible plants in my house, so I made these self watering pots from recycled materials that anyone can get. I've seen similar pots using just a plastic bottle, but to be honest I tried it and something green (I think algae) grew inside because the transparency of the bottle allows light to enter, that problem is solved with the can.

Step 1: Self Watering Pot


-Soda can
-Plant pot (it can be the top part of a plastic bottle, a used coffee capsule, an actual plant pot, etc.)
-Absorbent thread (I cut a strip of fabric from an old sock)


-Can opener
-Knife (I'm using the one in my swiss tool)

Step 2: Remove the Top of the Can

Use the can opener as usual, but with the soda can

Step 3: Make a Hole (if Necessary) and Insert the Thread

Use the knife to drill a hole in the bottom of the pot. Measure the approximate height from the bottom of the can to the pot hole and tie a knot large enough that it does not go through the hole.

Step 4: Assemble

Fill the pot with soil, the can with water, and put the pot in the can.

Step 5: Mechanical Water Meter


-Small tube (An old pen or a plastic popsicle stick will do!)
-2 bottle caps
-Wire (I used clips)
-Cable for protoboard

PD: Sorry for the color inconsistancy, it was a lot of trial and error

Step 6: Make the Meter

Cut one of the caps to have only the flat top. Drill holes in the center of both caps. Assemble the structure with the caps and the wire. Cover the flat cap with aluminum.

Step 7: Make the Sensor

Make the tube go through bot cap holes. Attach the cable to the tube to make the sensor, use 2 cables that will be conductively joined by the aluminum when going up or down.

Step 8: Some Considerations

Make sure the sensor rises with the water level, you might have to build a structure inside to prevent water from seeping in.

Make sure the conductivity is taking place, I struggled a lot with the lower cables and had to remove the variables with a wire triangle and fixing the position of the meter with the cables.

I am sure there are more ways to solve these problems, if you have one please share it :)

Step 9: Put the Sensor in the Can

Drill holes in the can. Place the sensor inside the can and pull the cables through the holes. Use more wire to fix the sensor.

Step 10: Electronic Circuit


-Mini protoboard
-Cable for protoboard
-TTL's as needed
-Green LED
-Red LED
-5V battery (I used an old powerbank)

Step 11: Design the Circuit

I want the red LED to light up when the water level is low, the green LED to light up when the water level is high and to retain its state when the water level is in the middle.

I made a truth table and used boolean algebra to use only NOR gates, so the only TTL I need is a 7402.

Step 12: Build a Basic Circuit to Test Conductivity

Optional but highly recommended. I am leaving the diagram in the images. Use the breadboard, resistors, and LEDs to make a circuit that illuminates only when the meter contacts the sensors. You can even leave it like that and use a third LED to make sure the circuit didn't run out of battery.

Step 13: Build the Sequential Circuit

Once again I am leaving the diagram in the images. It is the most practical way I found, but it is not the only one, if you feel more comfortable using another gate configuration, go ahead!

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    2 years ago

    This is not hydroponic.
    Hydroponic use zero soil and nutrient solution in water.
    This is self watering.


    Reply 2 years ago

    I didn't know, my bad. Correction made.


    2 years ago on Step 13

    Nice instructable. I'm a noob when it comes to electronics.
    I was wondering if you could tell me were i should connect the powersource to the breadboard?


    Reply 2 years ago

    Hello Rich, thank you for your comment.

    On a breadboard, the hole strips are connected to each other. We want the 5Vs to travel from the powersource to one of the sensor cables and to the other cable when the water level is up or down.

    So the power supply must be connected to 1 cable from each level of the sensor and the other sensor cable to the rest of the circuit as input. You can see this visually explained in the image that I attach.

    If your question is about the TTL, that depends on which one you are using and should look for the datasheet, but is usually as the one in the second picture.

    Let me know if you have any other questions or if I did not explain myself well.

    Penolopy Bulnick
    Penolopy Bulnick

    2 years ago

    Nice job on your first Instructable :)


    Reply 2 years ago

    Thank you so much!! :D