We scanned a new reverse osmosis filter, ran it for two months in a hard-water environment, and scanned it again. Scaling deposits of minerals are clearly visible in the used-filter CT scan. As they accumulate, they restrict flow through the filter and reduce efficiency.

The water’s flow pattern is clearly visible in the medium: water flows in along the outer edges of the cartridge, then through the medium to the center channel before heading to the refrigerator’s ice maker.

Here we’ve used @lumafield’s automated inclusion analysis tool to identify areas that are particularly dense. The densest impurities, highlighted as purple and red specks, have been getting strained out toward the top of the filter medium.

As the filter medium inside this Brita cartridge is used, it swells and cracks. Clearly-defined flow channels are visible, suggesting water is following the same path through the filter media each time.

Industrial CT scans capture both geometry and density. We take X-ray images from different angles and reconstruct them into a 3D model. A dark area in a 2D X-ray could be either thicker or denser material; with CT we can separate geometry from density, shown in red/blue in this @lumafield scan.

Do water filters actually do anything? We CT scanned several popular water filters before and after use to see what they’re able to keep out of your body. Here’s what we found… 🧵