What's inside a water filter?

Teardown

Ever wondered what's inside those cartridge-type water filters that go inside your refrigerator? I decided to find out. They are not cheap--they cost about $40 at Lowe's or Home Depot and you're supposed to replace them every 6 months.

1. Hacksaw time! The cartridge is made of thick, sturdy plastic that is easily cut with a hacksaw.


2. Once the end is off, the inner cartridge slides right out. It's a dense cylinder wrapped in a white membrane, with a white foam cap on top.


3. The top end of the cylinder is sealed. The other end plugs into the water inlet at the bottom of the cartridge.
   
   


4. Pulling the top off of the cylinder is kinda messy. The cylinder is full of compressed black powder, which I assume is activated carbon. It isn't clear in the photo, but there' s a channel through the center of the carbon.

Summary

Water enters the nipple at the center of the bottom end of the filter cartridge. The pressure forces the water up the center channel and out through the porous carbon, which removes contaminants. The water finally passes through the white filter paper wrapped around the carbon, which keeps bits of carbon out of your glass of water. The filtered water exits the filter cartridge through the other nipple at the bottom.