A water detector powered by a LiPO battery that transmits its status and notifications via MQTT to Home Assistant.
A while back my indoor air conditioner air handler's condensation pipe clogged and caused a small flood. Thankfully we were home and so it didn't cause much damage. So instead of being sensible and getting a $15 water alarm from Home Depot, I decided to spend an inordinate amount of time, money, and effort into creating a water alarm device I could put anywhere and notify me if a water leak happens again. My version will not only screech an annoying pitch at me but will also send me a notification to my Home Assistant which will let me know via phone and email. Oh.. and it should run on a 2500 mAh LiPO battery for about 2439 hours or around 101 days and 15 hours (according to http://www.of-things.de/battery-life-calculator.php)
- Battery powered - No need to run power cables to the device. Battery can last several months before recharging.
- WifI enabled - Sends MQTT notifications to my Home Assistant server.
- Battery level warnings - Notifies me via Home Assistant when battery level is low.
- Small and easy to install - Once reprogrammed with your wifi and MQTT server settings, set it where water needs to be detected (like at the bottom of your air handler unit).
https://www.youtube.com/watch?v=lflMII9bm8M
Top view of Enclosure.
Bottom view of enclosure. The probes are stainless steel legs on the bottom.
Top view with cover open. Buzzer and battery attached.
Top view with battery removed. Circuitry exposed.
Whole unit exposed but still connected.
- ESP8266 (https://www.amazon.com/gp/product/B01M4IOFIT)
- ESP8266 Serial Port WiFi Module Adapter Plate (https://www.amazon.com/gp/product/B01NCQFSEG)
- 2500mAh LiPO battery (https://www.adafruit.com/product/328)
- FTDI Mini USB to TTL Serial Converter Adapter Module to program ESP (https://www.amazon.com/gp/product/B00IJXZQ7C/)
- Low Power Labs' TPL 5110 (https://lowpowerlab.com/shop/product/147?search=tpl5110) or Adafruit TPL5110 (https://www.adafruit.com/product/3435)
- Pololu Mini Pushbutton Power Switch with Reverse Voltage Protection (https://www.pololu.com/product/2808)
- JST Connectors (https://www.amazon.com/gp/product/B07449V33P)
- 5v DC Buzzer (https://www.amazon.com/gp/product/B0716FD838)
- 1 - 220k ohm resistor and 1 - 1m ohm resistor (To divide voltage from battery and calculate its capacity with the ESP's ADC pin.)
- 2 - 1 k ohm resistors
- 1- 150k to 170 k ohm resistor to control the TPL5110 delay. This one is needed if using Low Power Lab's TPL5110. Adafruit's TPL has an adjustable potentiometer to control the delay.
- 2 - BC337 NPN transistors
- Rust-proof water probes (https://www.amazon.com/gp/product/B07L94MMP7)
The battery powers the TPL5110 and the Pololu switch directly. The TPL is the timer that will wake up the ESP (by sending an ON signal to the Pololu switch which then turns on the ESP) at specific intervals to read the battery voltage and send an MQTT message with its status (voltage % and raw ADC value as well as the previous and current sensor status). The TPL triggers every 90 minutes or so. The Pololu switch reads the status of the probes and starts the ESP if the sensor probes signal closes (water or something else makes contact with the probes and closes the circuit).
The ESP's ADC pin is rated for 1 volt. A 1m ohm and 220k ohm resistors are used to divide the voltage to less than 1v before it is read by the ADC. (More at https://learn.adafruit.com/using-ifttt-with-adafruit-io/wiring#battery-tracking)
When the ESP's sketch is done it sends a signal to the DONE pin of both the TPL and the Pololu circuits, causing them to cut power to the ESP.
When dormant, the whole project draws about 8 micro amps. When the EPS is turned on the sketch takes about 10 seconds to run and consumes an average of about 82 milliamps.
As previously stated, the sensor as is should run for about 2439 hours or around 101 days and 15 hours with a 2500 mAh Lipo battery. However it may last a lot longer than 100 days if I update my code to send the MQTT notifications every x number of times it wakes up. The variable counter_limit_wakeup, which is set to 1 by default, controls this. When it wakes up, the ESP will increase an internal counter and then go right back to sleep if the counter_limit_wakeup hasn't been reached, thus not spending energy turning wifi or sending any data. When the counter reaches counter_limit_wakeup then it will send go through the whole sketch. The TPL has a maximum delay of 2 hours, but it's not really needed to check the battery voltage that often. I can set counter_limit_wakeup = 6; an the sensor will send the message every 12 times it runs, thus sending the notification twice per day. Setting it to counter_limit_wakeup = 12; will send the notification about once every 24 hours. However, since I am still testing the system, I am not using this feature yet and so it's set to 1. Of course the counter_limit_wakeup is ignored if the ESP detects water present.
The following video shows how to solder the ESP to the plate and how to program it using the Arduino IDE: https://www.youtube.com/watch?v=O2SSyfP6OM0
The code can be found in the included ino file.
I designed the enclosure using Fusion360. You can view and download it here https://a360.co/2OCKjhl . I printed it with a Prusa MK3 using PLA.(https://www.youtube.com/embed/VsiMdKhxB_E)
Use the configuration.yaml, groups.yaml, and automations.yaml scripts to integrate the device into your Home Assistant.
Home Assistan card with sensor information - Pushbullet notification
The main sources of inspiration and ideas to make this project come to life are:
- http://benlo.com/esp8266/esp8266WaterAlarm.html - Mr. Jennings provided the idea of using the Pololu switch to trigger the alarm when water was present.
- https://learn.adafruit.com/using-ifttt-with-adafruit-io/wiring#battery-tracking - For battery voltage tracking.
- http://www.of-things.de/battery-life-calculator.php - Andreas Spiess' IOT battery calculator.