Water filters are our silent guardians, protecting us from a whole host of invisible contaminants. But what’s happening inside them as they work tirelessly to deliver clean water? With industrial CT scanning, we can take a detailed look at the internal structure of water filters—before and after use—to uncover how they perform, age, and ultimately safeguard our health.

In this deep dive, we’ll explore four types of water filters: pitcher filters, refrigerator water filters, reverse osmosis filters, and the LifeStraw. By getting to know their inner workings, we can see how each design contributes to its effectiveness and how they handle the wear and tear of daily use.

Pitcher Water Filters

Pitcher filters are household staples, using a blend of activated carbon and ion-exchange resin to trap impurities such as chlorine, sediment, and heavy metals like lead. When water passes through, the carbon absorbs contaminants, while the resin removes specific ions to improve taste and safety. 

A CT scan of a new pitcher filter reveals a porous, uniform core of activated carbon and resin. The material’s consistency ensures even water filtration throughout the cartridge. After use, however, the scan tells a different story. Clearly-defined flow channels are visible, suggesting that water is following the same path through the filter media each time, limiting the thoroughness of filtration. The once-pristine pores are partially blocked by accumulated sediment and impurities, and denser particles have migrated to the outer edges of the core—indicators that consistent, uniform filtration is a thing of the past for this particular filter.

Refrigerator Water Filters

Refrigerator water filters deliver clean water for drinking and ice, and we barely notice them because they are directly connected to a water line. These filters rely on dense activated carbon cores enclosed within sturdy plastic shells.

In a new refrigerator filter, CT highlights the robust, porous structure of the carbon core. This setup is ideal for trapping particles, chlorine, and even some volatile organic compounds. Over time, as the filter absorbs these impurities, the core grows noticeably denser as the filter absorbs contaminants day in and day out. Notice the reversal in the relative density of the components: initially, the plastic casing was the densest element, but over time, the filtration media becomes markedly denser than the outer shell. 

Reverse Osmosis Water Filters

Reverse osmosis filters take water purification to the next level, using a semi-permeable membrane composed of tightly wound layers of synthetic material. These layers create microscopic pores that allow water molecules to pass through while blocking contaminants like salts, minerals, and chemicals. The membrane is often supported by a mesh or fabric backing and enclosed in a cylindrical housing for durability and ease of installation. Reverse osmosis systems are the go-to for ultra-clean water.

We worked with the GEAR Lab at MIT to compare new vs. used reverse osmosis elements. Our scan of a new reverse osmosis filter looks almost like a lithium-ion battery, with delicate but uniform layers surrounding a columnar core. Water has a pathway, impeded as it should be only by the membrane’s mesh pores. The filter worked 12 hours on, 12 hours off, for two months, then we scanned it again. Having purified a hard water supply high in mineral content, the filter now displays scars of its valiant efforts. Scaling deposits of minerals and organic matter visibly clog the layers, restricting water flow and reducing filtration efficiency.

LifeStraw

The LifeStraw is a portable, personal water filter designed for outdoor adventures, travel in areas with unreliable water quality, and emergency preparedness. Unlike reverse osmosis, which relies on a semi-permeable membrane to remove dissolved solids, the LifeStraw uses hollow fiber membranes with microscopic pores to physically block contaminants like bacteria, parasites, and microplastics. This ensures clean drinking water on the go, without requiring electricity or extensive setup, making it ideal for hikers, campers, and those in disaster relief situations.

A CT scan of a new LifeStraw reveals its uniform, open hollow fibers, which allow water to flow freely while trapping harmful particles along the way. Over time, and with frequent use, these fibers near the inlet begin to clog as debris accumulates, reducing both flow efficiency and the safety of the water that passes through. That makes regular cleaning a must for maintaining the performance of LifeStraw in challenging environments.

Filtration for the Future

Industrial CT offers a new level of transparency into the performance and lifespan of water filters. For consumers, it provides valuable insights into the unseen changes filters undergo, helping them make informed decisions about when to replace a filter to maintain the highest water quality. It removes the guesswork, letting us see the tangible effects of contaminants and wear over time.

For manufacturers, CT scanning unlocks critical opportunities to refine designs and materials. By understanding exactly how and where blockages form, they can create filters that are not only more efficient but also longer-lasting and better suited to the diverse needs of their customers. Whether it’s tweaking carbon density or optimizing membrane layers, these improvements translate into more reliable products.

Filters are more than just tools—they’re protectors of our health and safety. CT scanning goes beyond the surface, offering a glimpse into their often overlooked work and paving the way for smarter designs. With this technology, we’re not just looking at filters; we’re transforming how they serve us, ensuring better water quality today and clearing the way for tomorrow’s innovations.