My last teardown got really messy, but that was because I didn't figure out how to do it right (nondestructively) until the day afterwards. Since I have all of my mess cleanup tools already set up, I decided to tackle projects I had been postponing because I knew they would be messy.

A Brita water filter cartridge is a consumable item to be replaced at regular intervals. From the Wikipedia page for Brita I learned the cartridge contents mostly consisted of "activated carbon" and "ion-exchange resin".

Some years back, Brita evolved their cartridges to have this inverted-cone shape at the top. This serves as a convenient handle for handling the filter during replacement, but I also understood it had the purpose of diverting the force of water. This filter needs time to do its job, and it is counterproductive to have a stream of tap water force their way directly into the filter. This diverter sends that force sideways.

Given this externally visible mechanism, I started wondering about whether there were any internal mechanisms out of sight. Is this filter just a simple container or are there clever internal baffles to optimize filtering capability? I was also curious if I could see any visible signs of a used filter. I live in an area with hard water where everything that touches water inevitably builds up hard scales. Would I see similar buildup inside a used filter?

When this filter was replaced, I set it aside to dry. I hope it would make things easier to handle and drying would increase the odds of seeing any hard water buildup that might be visible. Once dried, I took a saw and cut it in half. I got the big mess I expected.

This is a closeup of the fine mesh keeping the filter particles out of my drinking water. This is the top mesh, molded from a slightly different textured plastic. There's also a counterpart bottom mesh. Other than these meshes, there are no internal structures of note inside the filter.

Matching Wikipedia description, I see two different types of material within. I would guess the angular black pieces are activated carbon, and the round translucent yellow-green balls are the ion-exchange resin. And unfortunately, because the action of sawing the cartridge in half created a lot of sawdust from the enclosure's white plastic, it was not possible to distinguish anything that might be hard water deposit on the filter material.