Simple way to detect water in a pipe...

[chconnor]

Hi - bit of an odd one, here... I'm a beginner, as you'll see:

I want to thread a wire down into an underground pipe from time to time to check for the presence of standing water.

My thought is to use a two-conductor wire, maybe 18-gauge, with a small (fixed) gap between the ends, and send high-voltage low-current electricity down the line.

I don't need to power anything with the "result" of the test, I just need any clumsy way to know if there is water down there... I can imagine using some old wall transformer, take the 9V or whatever it is and go through another transformer, maybe bust out some Ohm's law to figure out some resistors to limit current?, and put some kind of LED or other bulb in the circuit that would indicate a closed connection.

But I'm sure there's a better/smarter way? Any ideas?

Thanks for any suggestions,
-c

 

[CHELLIE]

hope this helps, Chellie

YouTube - Water Detector



https://www.youtube.com/watch?v=9OiC94RBjXY&feature=related

 

[chconnor]

Thanks

Thanks - for some reason I got it in my head that I needed rather high voltage to get through water. Guess not. I will cobble together something functional with a simple ~9V adapter.

Much obliged,
-c

 

[CHELLIE]

Glad I was able to help Take care and have fun, Chellie

 

[MikeMl]

Electrolysis of water due to passing current between metallic electrodes happens at relatively low voltages; <2V. Even a 9V battery in series with a DC meter (try 50uA to 10mA full scale) would show when water is present.

 

[crutschow]

An ohmmeter may also be able to detect a resistance across the wires, indicating the presence of water.

 

[ericgibbs]

hi ch,
We are assuming a plastic or other non-conducting pipe material and not copper.

 

[MikeMl]

If the pipe is metallic, you could send a single, insulated wire down the bore, where the end has a stainless-steel electrode with plastic spacers which would prevent the electrode from touching the pipe. A current-source of a few tens or hundreds of uA with an open circuit voltage of ~10V applied between the pipe and the electrode will show a voltage of either 10V (no water) or ~2V (electrode in water).

If you are worried about electrolysis, use an AC constant-current source, and an AC voltage detector.