These are designed to remove larger particles like dirt, sand, and rust from water. Typically made of polypropylene or cellulose, they often come in different micron ratings. These filters use activated carbon to absorb impurities, including chlorine, volatile organic compounds (VOCs), and bad odors. They can be granular or block-style. This type of filter removes a wide range of contaminants, including salts, heavy metals, and microorganisms, by forcing water through a semi-permeable membrane.