Winland Electronics WaterBug Sensor

DIY: Connecting a WaterBug Water Sensor to an Ecobee Smart Thermostat 22

WaterBug Water SensorI’ve already written plenty of posts about my experiences with the Ecobee Smart Thermostat. To say I’m a fan would be putting it mildly. But today, I became an even bigger fan after extending the functionality of my Ecobee Smart Thermostat by connecting a water sensor to it.

My basement utility room floor has already been wet more than once. First, it was a sewer line backup (ew… I know…). Luckily, that was while the house was still under construction, and so nothing got ruined. Next, it was a leaky furnace… well, technically it was a clog in the pump that removes condensation buildup from inside the furnace, and that did ruin some carpet. I’m not going to wait around for it to get wet a third time — especially given the number of potential water hazards in that utility room: the main water inlet to the house, a hot water tank, a water softening system, a water pressure tank, and two furnaces — both with condensation pumps that could clog or fail.

For $20 or so, you can buy a battery operated water sensor that sits on the floor and beeps if it senses water. Boooooooorrrrrriiiiiiiiiiinnnnnnggggg. Readers of my blog will know that’s not how I roll. That approach is a low-tech gamble that a potential water leak will occur only when you’re home, and awake, and within hearing range of the alarm.

For just slightly more money (they’re $55 on Amazon) the WaterBug water sensor is still cheap insurance, and opens up a world of automation and alert possibilities. Here’s what it looks like:

Winland Electronics WaterBug Sensor

Winland Electronics WaterBug Sensor

It has six terminals across the front. From left to right they’re marked V+ / GND / S / S / C / NO / NC, which stand for voltage, ground, sensor, sensor, common, normally open, and normally closed. The sensor sits on the floor near where you want to check for water, with its four metal contacts touching the floor, and connects with two wires into the two “S” terminals on the unit. If water touches either set of metal connectors, it “closes” the circuit.

However, the WaterBug has no on-board alarm, so in order to alert you that it’s sensed water, you need to wire its common (C) normally open (NO) terminals into something that can accepts a dry contact input. When the unit senses water via the S terminals, it uses a relay to close those C and NO terminals, thereby “closing” the “normally open” connection. Incidentally, because the sensor is completely submersible, you could alternatively use the normally closed (NC) and common (C) terminals on the WaterBug in instances where you want water to be present, and trigger an alert if something runs dry or the water drops below a certain level. For around $50, it’s surprisingly flexible.

Most people wire water sensors to the dry contact inputs in their home alarm systems. I do intend to do that that eventually, but I first wanted to test out the dry contact inputs on my Ecobee Smart Thermostat, so I wired then into the IN1+ and IN1- terminals on my thermostat’s equipment interface (the Ecobee actually supports up to two dry contacts).

The only problem remaining was figuring out how to get power to the WaterBug, since you have to buy a power adapter separately. But like I said before, it’s extremely versatile, and can accept anywhere from 8-28 volts — either direct current (DC) or alternating current (AC). Because the Ecobee thermostat receives 24V AC power from the furnace, I simply killed the power to my furnace (thereby killing the power to the Ecobee) and piggy-backed a set of wires from the Ecobee equipment interface power and ground terminal, then connected them to the V+ and GND terminals on the WaterBug. When I turned the furnace back on, both the Ecobee and WaterBug powered up!

Configuring the Ecobee to work with the WaterBug was a snap. I simply named the input in the Ecobee’s installation menu, and left it on the default of “normally open” when prompted for the contact type.

I tested my new setup by placing the WaterBug’s sensor in a bowl of water. Because the three thermostats in this house are grouped together, all three of them (one on each floor) immediately started beeping and displaying a message that the water sensor was “closed.” I also immediately received three emails, one from each thermostat, with that same alert (I’ve already reported a feature request to Ecobee to ask if it’s possible to configure it so only one email alert gets triggered when grouped thermostats receive a contact closure).

After acknowledging the alert on one of my Ecobee’s screens, the beeping stopped, but the message “Basmnt Water sensor closed” still appeared on the screen of the thermostat connected to the WaterBug. I removed the sensor from the bowl of water and the message disappeared. Success!

So if you’re an Ecobee owner who wants to squeeze a bit more utility out of your already amazing thermostat, consider dropping another 50-or-so bucks on a device that allows you to detect water leaks. If a leak ever does occur, that $50 will be money well spent if you catch the source early.

My next project with the WaterBug will be to connect and configure it as a wireless alarm contact (it’s too far away from my DSC alarm panel to hard wire easily). That way, it will still alert my Ecobees, but my alarm monitoring company will call and text me, just in case I’m not at home or checking email when a leak happens. After that, I may look at connecting the WaterBug to an automated shut off valve that cuts water to the house automatically when it senses a leak.

If you’ve got questions, comments, or interesting ideas of how to use (or how you’ve used) a water sensor in a home automation application, I’d love to hear from you in the comments!

  • Anonymous

    Great post, just did the same to my setup and it is working perfectly. Had a water issue with my HVAC this summer… with this, response time will be instantly. Thank you.

  • Dominique

    Thanks for presenting this hardware! Have you considered connecting the sensor directly to the Ecobee dry contact input instead of going through the WB200? Since water across the sensor will essentially close the circuit, I wonder what more work is the WB200 doing in this setup? I understand a relay needs to be powered in order to get the normally-closed behavior, but this is not needed here (and the Ecobee can provide this if needed). Winland does sell the sensor alone (called W-S-U) for around 20$.

    • Hey, Dominique. It might work, but I haven’t tested it. I don’t know if water across the sensors does indeed close the circuit, or if it simply provides a big enough change in resistance to trigger the internal electronics of the WB200, which in turn closes its circuit. If I get a spare moment tomorrow, I may test it out!

      • ohliuw

        Have you tried hooking up the sensor directly to the dry input? I am considering getting this setup in a new home, so I was curious if it actually worked?

        If it did, I would like to know if it’s posible to wire several sensors in parallel and place them in different locations around the house, and then connect them all to the same dry input?


        • I confirmed that the sensor doesn’t work when connected directly to the Ecobee. It has to go through the Waterbug, but the good news is yes – you can wire multiple sensors to one Waterbug, which is connected to the same dry input.

          • ohliuw


            I found a sensor that claims to provide dry contact closure – W-600:


            It looks like it should work.

          • Dominique

            Same here. Got the sensor, hooked it up to the Ecobee, dipped it in water: nothing. So I’ll have to purchase the full system: WB200 in my case. This means I will have an additional sensor so I’ll be able to monitor to different locations in my house. The WB200 can monitor up to 6, according to the doc.

  • ohliuw

    I am by no means an epxert in electricity, so I have a question.

    Suppose that the Protected Home WS-600 Water Sensor does the job as advertised. In this case, would I be able to place 4-5 sensors in different locations and wire them in parallel to the same dry contact and get an alarm triggered? If yes, what sort of cable should I use? the longest run would be about 50ft. Could I use a twisted pair from a Cat6 cable?


    • I can’t speak for the WS-600, but with the WB-200 that I used, you can connect up to 6 sensors in parallel. Since it’s low voltage, a twisted pair from a Cat5/Cat6 should be fine.

  • ohliuw

    Thanks Steve, I plan to test it out and report, but will only move into my new home in August, so I won’t be able to test it until then.

    I was also thinking of using the second dry connect to hook up my doors/windows sensors. Any magnet switch should work, no? (for example this one:

    Just wonder if the Ecobee interface allows you to specify to send an alert when the circiut become OPEN and to stay idle when the circuit is CLOSED because most door sensors open the circuit when the door is open?

    As for the wiring, I plan on running 4/22 cable to each location – keeping one spare pair just in case.

    • Yep – you can have the Ecobee monitor either NC (normally closed) or NO (normally open) contacts. That magnet contact should work great.

      If you’re wiring contacts to windows and doors, it’s a good idea to home-run them all to a single room anyway, and give yourself plenty of extra wire on each lead. That way, if you decide to upgrade to a full alarm system, you can just install the panel somewhere in the utility room and wire it up. It may not be a bad idea to wire to some keypad locations (near entry doors + master bedroom), even if you just hide the wire inside the drywall, so you can later punch out a hole and put in a keypad. With integrated wiring, always best to think WAY ahead. 🙂

  • ohliuw

    Thanks, that’s my plan – I will BIX them on 10A mount and five BIX 1A connectors 🙂

    Btw. I also plan to test the sensor from the following $10 water alarm – the sensor looks like a simple switch. Worst case will use it a buzzer alarm:) Will keep posted.

    Finally, do you think that Aleph motion detectors with dry contactas alarm output would work with Ecobee as well? For example, this one states:

    Alarm Output NC dry contact, 30VDC, 0.5A, 5W max.

    Let me know what you think.

    • Yep – ANY dry contact closure should work just fine. The Ecobee merely has two leads to which you connect, and it senses whether or not the leads are touching on the other end. Simple! 🙂

  • Henry

    I found your post while trying to figure out how to wire a WaterBug200 to a 12v piezo buzzer on a boat. I am thinking I can use a standard automobile relay to switch 12v to the buzzer when the contacts close but I have not figured it out yet.

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  • kjake

    Great write-up on this. Easy install and makes me feel better that my 10 year old water heater and nearby water softener are monitored should they decide to misbehave.

    • Thx, Kevin. It does give me a bit more piece of mind. I’ve had leaks in the utility room before…

  • Tony

    Hi Steve,

    Interesting setup. I am trying to do a similar setup with wireless water sensors that could trigger a electric water shut-off valve. That would be a step further ahead in that a positive water event would automatically shut-off the water main until someone could investigate and address any leaks. Most of these electric valves have a manual override in case of false alarms. Here are the sensors and valve I have found so far however I as of now still do not have an answer on how to trigger the electric valve. Hoping you can help or direct me in the right direction.

    All the Best, Tony

  • Amir

    Awesome write up, thanks Steve! I am a complete newb to this kind of stuff but your write-up was very easy to follow and gave me some DIY confidence. The result? My set up works like a charm!!! Thanks again!

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  • No. 🙁 One of the things you give up with the ecobee3 vs the original ecobee Smart is dry contact closures for devices like the waterbug.

  • Jason Berna

    Just curious if you have a wiring diagram
    If I just supply + and – what wire on the sensor goes to the thermostat for the trigger