Text "Simple Circuit Challenge - Overflow Alarm" and two boys in cartoon tub with battery and flashing light.

STEM Challenge: Make an overflow alarm

Can you make an overflow alarm with just a few basic supplies? To do this STEM challenge, kids try to build a buzzer that goes off before water overflows from a tub.

STEM stands for Science Technology, Engineering, and Math.

This is a great activity  to do with school-aged kids in the classroom, as a homeschool activity, or in a makerspace. 

This project and all Geek Pack Hack activities must be undertaken with a suitable adult completing their own risk assessment and supervising their children at all times.

Since electricity can only flow through a complete circuit, this STEM challenge is to figure out some way for rising water to complete an electrical circuit to sound the alarm before the water overflows from a tub.

We’ll list the parts we used and then show you how we were able to wire up this overflow alarm

There’s a lot of flexibility with the specific supplies you use and how you can create the circuit. This activity inspires creativity, problem-solving, and hands-on learning fun! 

Here are the supplies you’ll need and instructions for one way to do this STEM challenge.

We encourage you to think about how else you might make this overflow alarm with different materials or a different design.

You can check out our video tutorial here and subscribe to our YouTube channel to keep up with new projects.

Everything is explained below as well.

STEM Challenge Supplies


9V Battery 

9V Battery connector 

Insulated wire 

Aluminum foil

Bubble wrap 


Wire connectors

Masking tape


Wire strippers

Container to hold water

STEM Challenge Steps

Step 1: Cut and strip the ends off a small piece of wire

Step 2: Make a partial circuit with the battery, buzzer, wire, and wire connector

Step 3: Make the float

Step 4: Tape everything to the tub

Step 5: Try it out!

Step 1: Cut and strip the ends off a small piece of wire

To prepare all the starting materials, cut a piece of wire that is a few inches long using wire strippers. Then, strip the insulation off each end of the wire.

Insulated wire with a few millimeters of insulation stripped off at each end

Step 2: Make a partial circuit with the battery, buzzer, wire, and wire connector.

Start creating a circuit with the battery, buzzer, wire, and wire connector. 

Separately insert each buzzer wire into each opening on one side of the wire connector. 

After attaching the battery connector to the 9V battery contacts, insert one of the battery connector leads into one of the unoccupied wire connector openings. 

In the last remaining unoccupied wire connector opening, insert the stripped wire.

The image below shows this partial circuit, along with the float that we’ll build in the next step.

Partial circuit to complete the STEM challenge consisting of 9V battery, battery connector, wire connector, buzzer, and insulated wire.

Step 3: Make the float

We made a conductive float by wrapping aluminum foil around a small, long pieces of bubble wrap. 

Make sure to run a piece of string through the float so that you have a way to attach the float to your container.

STEM challenge float made by wrapping bubble wrap with aluminum foil and threading a string through it.

Step 4: Tape everything to the tub

This step requires some patience and persistence to get everything lined up properly. 

The goal is to arrange the float so that it rises up with the water level in order to make contact and complete the buzzer circuit before the water overflow.

Step 5: Try it out!

See how it goes! If it doesn’t work the first time, can you figure out what went wrong and tweak your design?

Pouring water into tub with overflow circuit affixed.

Stay in touch!

Share your projects, your successes, and your failures with us! Tag @geekpackhack on Instagram, or leave a comment on this post.

Please also leave us a comment if you enjoyed this project or have questions.

Check out all of our cool engineering projects.

Or, narrow in on our simplest basic electrical circuit projects or our slightly more advanced electrical engineering projects. 

We also have a helpful basic electronics page that teaches skills such as how to use a breadboard and multimeter.

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