We had a humidifier leak in the furnace room and it ruined a portion of the laminate flooring that had to be replaced. I didn't want it to happen again.

Lining a pail with a matrix of thin wire hooked up to a 555 timer buzzer circuit would alert me to a leak before too much water accumulated.

A future version of this project will have an ESP32 that will be energized when the leak is detected. It will sound the alarm AND it will send me an email via the IFTTT IOT service telling me I have a humidifier leak.

This is a quick Instructable for the basic alarm circuit.

Supplies

Enough thin wire to make a parallel matrix in the bucket of your choice. I used 24AWG nichrome wire I had in the shop.

Suitable bucket to place under the humidifier.

Parts for basic 555 timer buzzer circuit of your choice such as: https://www.eleccircuit.com/voice-warming-by-ic-555/#1_Simple_555_alarm_sound_generator

Electrical tape and/or foaming glue (like Gorilla glue).

Table salt (Yep!)

Step 1: Build the Buzzer Circuit

Build the 555 timer buzzer circuit of your choosing and have a way to connect the circuit to your wire matrix. I used some female terminal strip on the buzzer circuit that is connect to male terminal strip that connects to the wire matrix via two alligator patch cords.

Step 2: Build the Wire Matrix

Cut two lengths of wire long enough to make a parallel snake-like path around the bottom of your bucket. I secured it with short lengths of electrical tape and then followed with dabs of Gorilla glue afterwards that would be more secure for the long term.

Step 3: Hook It Up!

Connect your buzzer circuit to the wire matrix as you wish. I used short alligator clip patch cords.

In testing with tap water, there isn't enough electrolyte in the water to complete the circuit when adjacent wires are shorted together by water.

To solve this, I sprinkled some table salt in the bottom of the bucket. When water enters the bucket it will dissolve enough of the salt to increase the electro-conductivity of the water across the wires, completing the circuit to activate the alarm buzzer.

Install it under your humidifier (or air conditioner condensate spout, washing machine, dishwasher) and hope you never hear it. But if you do hear it, you'll be thankful you built the project!

Step 4: Future Work

Eventually, I'll make a small ESP32 circuit/sketch to alert me via email that a leak has happened. It will likely be powered by a 9V battery and be in the OFF state until water shorts the wire matrix. Then it will use the IFTTT IOT event service to send me the notification email. I'll put an updated link here once that project is finished.