A way to detect water on floor

Projects General Guidance
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I'm trying to think of ways top detect liquid on a floor. I have these soil moisture sensors.

I guess they could work. I was thinking of a way to maybe put a wick across the electrodes that when water is present the wick picks it up and it causes conductivity.

Another though was submerging the soil moister electrodes into some dry salt. have the wick bring water to the salt. this of course would be one time use, that's fine with me.

I'm open to ideas. not sure what sensors are available to help with this task.

Another thought i had, if i took 2 pieces of copper tape and put a insulator between them, i could lay them on the floor and wait for conductivity?

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The last idea will work. Or, just lay down two bare copper wires, separated by a couple of mm, and tape them to the floor. Water from a leak will eventually get under the tape and increase the conductivity between the wires.

These alarms are pretty cool, at about $10 each. They run for years from 2xAA batteries, operate independently, but can also notify you of a leak via the web, through your WiFi system.

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One concern i have with any of the ideas, will the wires touching the floor cause some kind of ground loops, or grounding issues. unpainted concrete floor.

Nice water detectors, i should probably use them when my device fails. I tend to want to overcomplicate things.

im thinking of ways i could insulate the sensors from earth,

maybe i could insulate both sides of the copper tape from conductivity, but in between the tape is a papertowell that will absorb the water into the layers of tape?

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Unpainted concrete floors are rather conductive, if clean. I think you will have to look for "changes" in resistivity, not conductance. They are great for dissipating static electricity.

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5

Thankyou for correcting me. this is my intention to measure resistivity. Im worried i would get lots of bogus readings. but i suppose i could set a threshold and a timer duration to trigger an alarm.

I guess i'm gonna build some tape sensors and find out. I could read them with my DMM.

6

look at sense cables or rope sensors and how they work

you could also look at small paper Pads for Leak Stop Valve systems. it's a small cylinder of "paper" that significantly expand when wet. if you put this small pad into a tube and have some sort of push button on top, you could detect that the paper got wet

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I took 2 pieces of copper tape 4x4 inch. I put a cheap paper towel in between the 2 pieces and soldered a wire to each side. i put 1 drop of water on the corner of the towell and when it got to the copper my meter read 2Mohm. then i completely saturated the towell it read 200k ohm.

It actually seemed to work pretty good.

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They are proud of them rope sensors. That seems to fit the project perfectly. They are pricey though.

I wonder how one would make them. some bare wires and a absorbant jacketing?

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yep that works

(something similar mentioned there Using two wires to detect water - making your own water sensor - #5 by Peter_I)

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I think they pulse current into a specific type of wire (with non-conductive polymer) and check what they get on the other side. The water will modify the propagation.

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I think im going to sprinkle some table salt on one side of the towell to decrease the resistance . the towell does a great job funneling in the water.

ill probably then roll them up in an insulated fashion and let them lay on the floor.

EDIT: i found that if i roll them up they conduct much better. i guess it dont have to go through the glues on the tape between layers

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Once again, don't even need any microcontroller, an old smoke alarm will do.
Plenty of details on the internet on how to do it.
Self contained right down to alarm, battery holder, mute switch etc. etc.

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