How Water Filters and Purifiers Work

Every water filter and many purifiers include an internal element or cartridge, a component that has microscopic pores that catch debris, protozoa and bacteria. Over time, strained matter gums up an element’s pores, requiring it to be cleaned and eventually replaced.

Most purifiers use chemicals (such as iodine) to kill viruses, which are too small for most filter elements. Another purification method relies instead on ultraviolet light to treat the pathogens.

Many filters and purifiers also include activated carbon in their elements because it’s effective at removing unpleasant tastes from things like leaf tannins. Activated carbon also reduces contaminants like pesticides and other industrial chemicals.