Smart Faucet Reminder — My DIY Solution
We sometimes forget and leave the kitchen faucet running. I looked into automatic faucets, but they’re expensive and would need a plumber to install. So, like with other things around the house, I started thinking about how I could tie something into our home automation system to warn us when the faucet is on.
On Amazon I found sensors you can install inline with your plumbing. They detect water flow and connect over Wi-Fi or Zigbee so they can integrate with home automation — but they cost over $200 and still require a plumber. Not much better than buying an expensive faucet!
Then I had an idea. Some clamp-on water alarms detect flow just by the sound of running water. Why couldn’t I do the same thing with a microphone and a small computer?
Well, it turns out I can.
First, I experimented on my laptop, which already has a mic. With some help from AI, I “directed” the creation of a Python program that listens through the mic and breaks the sound into all its frequency bands (using an FFT — Fast Fourier Transform). I added a simple graph to show the sound spectrum, and visually discovered where running water has the most energy. With that, we were able to build software logic that detects when the faucet is on or off — and it worked!
Next, I needed something that could stay by the sink. I used a spare Raspberry Pi 4 and a $4 USB mic from an old project, and got the same program running there. After a little tuning, it became a reliable running-water detector. From Python it’s easy to trigger events on my home automation system, so I created a rule: whenever the faucet alarm switch turns on, my living-room speaker announces “Faucet On!”
It works perfectly — and it cost me nothing but a bit of time and curiosity. I saved hundreds of dollars and learned something new in the process.
Stefanos's Blog 