What does gravel do to filter water?

Short answer: gravel filters don't decontaminate water, they just remove suspended solid particles. Extensive answer: The action of removing suspended solid particles is defined as screening. read more

In part, the same way a kitchen strainer does, by physically obstructing the dirt particles in the water. You can think of each 2–3 millimeters layer of sand as ANOTHER strainer screen, so that an entire filter is composed of many layers of ‘screening’. read more

If the water source is limited or intermittent the filtered water can be pumped back to the top of the supernatant (the water on top of the sand) when necessary, but this does require pumping and control gear. Further treatment Sand filters provide good quality drinking water and many people use them successfully. read more

Hey , Sand and gravel filter acts as a check for the suspended particles in the water. The cohesive and adhesive forces between the the suspended particles and sand,gravel ensures sticking of the particle in the surface of sand and gravel . Hence purify the water. read more