I am thinking of creating a device that will detect water leaking/ water detection. I am currently using this: enter image description here

And this one I want but it is costly and not available on Amazon India or flipkart : enter image description here

I don't know if there is a small alternative for water detection as good as them. I tried searching but what I am getting was these sensors. So if you guys know any small size sensor to detect water presence please let me know. And if it comes with buzzer it will be a lot of help.

  • Hello. Is it simply humidity/water you are looking to detect or specifically rainfall? Will the sensor be submerged in water for example?
    – Natsu Kage
    Commented Jan 24, 2020 at 19:31
  • @NatsuKage I am looking for detecting water specifically. It should generate a signal on even a single drop of water like a raindrop sensor. For example, Sensor used in a bedwetting alarm. It should not be costly and should be small in size.
    – Lucifer
    Commented Jan 27, 2020 at 5:46

2 Answers 2


The sensors shown are simply conductors separated by an insulating space. When water, which conducts electricity slightly when pure (or much better with dissolved ionic substances), bridges the gap, it completes the circuit. All you need are two conductors, separated from each other by an insulator such as air, PCB plastic or cloth.

If expense is a priority, make your own. Just weave two bare copper wires in parallel through a piece of nonconductive material such as nylon fabric. You can customize the size, flexibility and other qualities to your needs. For a bed-wetting or diaper sensor, use thin wires and material for comfort, going to two heavier ones for the connection to the rest of the circuit, for strength. For a diaper alarm, just put the sensor in an are likely to get wet; there's not need to wrap the whole diaper. BTW, disposable diapers contain absorbents that prevent the outside from getting wet, and I do not suggest putting a sensor inside, against a baby's sensitive skin. Ummm... and sterilize the sensor after use with bleach or hot water.

The solid PC boards you show might be more useful in detecting water on a floor or window, though.

  • How will this work? How will this detect? and are you saying to wind the wire around the diaper? because I want to make a portable one so I can't wind it around every Diaper. Also, will this generate a signal so I can pass it from a transistor(as a switch) and start buzzer? Can you please elaborate on your answer?
    – Lucifer
    Commented Jan 28, 2020 at 6:29
  • @Lucifer, your sensor would just be a swatch of nylon, perhaps a few cm square, placed outside the diaper in a spot likely to become damp. Commented Jan 28, 2020 at 17:15
  • Okay. I understood. Two copper wire connected to the transistor (which will work as a switch).Like this circuit:iamtechnical.com/sites/default/files/…. Just instead of LEDs, there will a buzzer and one copper wire will be from Base and one from collector with little space between them or between the area which will get wet. As soon as the water starts it will be a conducting material between these two copper wire and will ring Buzzer, right?
    – Lucifer
    Commented Jan 29, 2020 at 5:47
  • @Lucifer, It might work... depending on "buzzer" current requirement, spacing of wires and conductivity of "water" (urine is a better conductor than rain water, so it's more likely to work for a diaper alarm. Be careful not to leave anything where an infant could get tangled in the cord or swallow parts!!! Commented Jan 29, 2020 at 19:06
  • Yeah, I will try it and create it. And also take care not to leave any open-wire or power issue to hurt the baby.
    – Lucifer
    Commented Jan 30, 2020 at 7:47

I made a diy flexible sensor for diaper-free time - not exactly what OP asked but still might be helpful. You can make it smaller with thinner tape and sheet but still probably not comfortable/usable within diaper. (Side note: Good diapers actually have wet color-changing strip on them, which is much more practical. You can just replace them every 3-4 hours or look at the strip.)

I used adhesive copper tape (2cm wide) to make the rain sensor-like pattern on top of OHP transparent printing sheet. I also printed out the pattern on OHP sheet to help lay out the tape (visible from back). This makes for a nice large A4-size sensor which is flexible, waterproof and not easy to tear. Then I use 2 alligator clip to attach to 2 rails and connect to mcu. It would be nice to upgrade to a single clip with 2 connectors to make it quicker to detach.

One issue I noticed is that human body resistance can also trigger false positive if you sleep directly on it (think of resistance of skin between two closest fingers of the sensor, not whole body resistance). Rather, I use a super-thin 20GSM hospital/salon-purpose bedsheet which is laid out on the sensor and lay the baby on this bedsheet. Because it's very thin and absorbent, as little as 3 drops of water easily soak to the bottom side and activate the sensor while increasing the non-wet resistance to infinity (beyond multimeter measurement). It's also more comfortable to sleep on.

Front side - Front side

Back side - Back side

20GSM hospital bedsheet example - https://zjhuachen.en.made-in-china.com/product/XxNRpFUvEScu/China-Disposable-Nonwoven-Bed-Sheets-of-Waterproof-Oilproof-20GSM-Spunbond-Non-Oven-Fabric-PP-Polypropylene-Non-Woven-Cloth-for-Beauty-Salon-SPA.html

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