Carbon filters are extremely effective at removing a wide variety of contaminants from water because of its adsorption properties. Through adsorption, contaminants are attracted to the activated carbon surface and held to it. This is similar to the way a magnet attracts and holds iron filings.
In fact, carbon's excellent adsorption capabilities have made it one of most common filtration mediums used in reverse osmosis drinking water systems, fridge filters, backpacking water filters, and more.