How to Use an Open/Closed Sensor as a Leak Detector

Sorry if there is already a thread dedicated to this concept and I just missed it.
When I saw this in the Deals thread, and wanted to discuss it more, I decided to yank it out of there and start a thread of its own…So,

Continuing the discussion from Current device deals & best prices:


First off, thanks for the tip!

I went to craft store and got some of this…

Is that about right?

Then, to use it, do I connect one each to the terminals, and then twist the pieces together so that if either one gets wet, it will soak through to the other one to make the connection, or just tape them closely together?

Once that part is figured out, do I just lay it out around where water would go if there is a leak (sort of like the leak detector that comes with the Rheem EcoNet WiFi Module)?

If so, do you have any idea what the length limit should be?
The reason I ask is that, if I could string a few of them together like this, I could have one sensor for two sinks in the bathroom…they’re a couple feet apart, and I would need to have the total length be probably three wires long.

Glad to help! I used a different wire but that should work. Twisting the wire seems to work well. I taped mine to an old yardstick so it would lie flat. Slipped it under the washer and mounted the sensor to the washer. The lengths of wire are about 40 in. +/-

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I may just go ahead and get a spool of that stuff, just to make sure at least that I’m working with the same thing from the get-go.

Do you think it would work OK to craft a ‘T’ intersection in order to send one section of the wires to the left under one sink, and the other the other direction (assuming there is a consistent connection the whole way), or would T-ing it like that cause any problem?

Also, sorry if I missed it in your other posts about this, but specifically which device handler are you using for this (link?)?

Not sure where I got the device type, I’ll see if I can find the link.


  • Generic Z-Wave ~Water Sensor
  • Author: SmartThings
  • Date: 2013-03-05 (updated 12/26/14 by JDE)
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I found it in the list of available Device Handlers in the IDE. However, when I’m in My Device Handlers, and choose to create a new one, and choose from template, and choose the one in the list, and then click Create, it comes back with this error message…
Org.codehaus.groovy.runtime.typehandling.GroovyCastException: Cannot cast object ‘water’ with class ‘java.lang.String’ to class 'int’”

I tried other templates and they still work fine. I don’t know enough yet to figure out what part of the code is the problem (or how to fix it if I did figure out where the problem lies). Do you? …or could you just post the code you’re using (are you on github?)?

Try this Generic Z-Wave ~Water Sensor.

You guys know this is a serious fire hazard, right? You get a leak under the washer, you’re going to set the dustbunnies on fire. There’s a reason that UL listed leak detectors use the designs that they do.

Just sayin’… :wink:

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No. I had no idea. I’m really glad you brought it up.

In what way are these a fire hazzard?
It doesn’t seem very likely to me that this described design would spark enough to light soggy dust bunnies on fire.

Am I way off?

Obviously, I’m slightly kidding. I can imagine that, if a large enough spark were possible from one of these tiny batteries, the long wire could be wet on one end, but completely dry on the other end, and if it just happened to spark right there on the dry end, if there were any bunnies close enough, it could ignite them and away we go…

I understand the proposed scenario. I’m just not so sure about the likelihood of it happening.
I don’t necessarily disagree either. I’m just not sure, and I think I’d like to find more info about it – either from you or Google; either way is fine :slight_smile: .


@TEWphotography just curious as to which terminals to use. I have three extra GoControl door sensors that I would like to use as leak detectors. Thanks!

Ok, I think I figured it out. You need to cut the case to make room for the wires. The wires can then attach to the green terminal.

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That’s it!! They even made the case wall thinner in that spot for easy drilling.

Good point. The sensor should be mounted to the side of the washer/H2O heater or wall above the water line. Only the wires should go to the area to be monitored.

Thanks for pointing this out.


Now using one to trigger an announcement that the mail has arrived.

Using a micro switch to trigger instead of the magnet so the sensor can be placed in the back of the box out of the way.

Next step - Solar battery charger

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Now adding one to a basic mouse trap to announce the execution umm I mean triggered event.
Seems one of the tiny buggers has come in to escape the cold. From the frying pan to the fire.


Ooo! This is really neat!
How did you do the hook-up? Just connect the wires to different parts of metal on the trap that don’t touch while sprung, and only touch when set off?

I’ll get it together this evening. I’m thinking one wire to the eye screw and one to the spring trap. Use a normal open/close contact sensor device type to trigger alert when open.

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I’m not saying this is the definition of home automation overkill but I am saying it’s getting close. Thanks for the chuckle. :slightly_smiling:



It’s only overkill if he doesn’t need or want to know whenever a mouse gets killed. :slight_smile:

The only problem for me is that I don’t use mechanically triggered traps. Perhaps I should mount a motion sensor right next to my glue traps? lol

New use for these little boxes.
Leak sensors work great. How about a tilt sensor for the mail box or other. I just attached a little ball in can tilt sensor (10/$1 on eBay) to the terminals. Instant tilt sensor.