What will a sand filter not effectively remove from water?

A sand filter operates primarily by using physical filtration to remove particles from water. This method effectively captures suspended solids, including bacteria and pathogens, as these contaminants tend to be larger and can be trapped within the porous medium of the sand.

Dissolved oxygen, in contrast, is not a solid particle but rather a gas that is evenly mixed in water. Since sand filters function through a physical barrier that captures solid particles, they do not have the capability to eliminate dissolved substances, including gases like oxygen. Therefore, while a sand filter is effective for certain types of contaminants, it is ineffective at removing dissolved oxygen from water. This distinction is fundamental to understanding how various water treatment methods operate and their specific applications.