The Berkey can also be harder to maintain than other systems, with long-lasting filters that require periodic cleaning. And it’s much, much slower, taking hours to filter a full 2.25-gallon tank.

Here's What Happened Companies that make gravity filters include Doulton, Boroux, Lifestraw, Waterdrop, and Glacier Fresh, among others. But the most classic gravity filter has to be the Berkey.