In simple terms, filter media are materials that facilitate the passing of raw untreated water through them, while retaining any impure particle matter, allowing now cleaner water to pass through. Each filter medium has specific characteristics such as size, weight, whether they are activated or non activated, gravity and more. All of these characteristics give rise to differing operational performance at certain filtration tasks – oftentimes a compromise between them is sought to provide the most robust system, or a system at a lower price point. Anthracite's broad tolerance of contaminants and ease of forming it into a filtration grade product make it a popular choice.

For drinking water, wastewater filtration and water for industrial use, anthracite has ideal properties for purifying and clarifying this type of water – especially when utilised in combination with other sand filters, or as a component of a dual- or multi-media filtration system.

Because of its ideal properties, relative ubiquity and ease of use, anthracite as a water filter medium is one of the most widely used around the world.