I’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

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!