Operator terms · Water
What is filtration in water treatment?
Filtration is passing water through a bed of sand, gravel, or other media to strain out the fine particles and floc that sedimentation left behind. It is a key barrier for removing turbidity and the organisms that hide in it, and it comes before disinfection in a surface-water plant.
Last reviewed 2026-08-03
Where it fits
Filtration follows coagulation, flocculation, and sedimentation. Those steps remove most of the load; the filter polishes what is left so the water is clear before disinfection.
Why clarity matters
Particles can shield organisms from disinfectant. Removing turbidity by filtration makes the disinfection step far more reliable.
Common questions
- What does a filter remove?
- Fine particles and floc that settling did not catch, lowering turbidity.
- What comes after filtration?
- Disinfection.
- Why does turbidity matter for disinfection?
- Particles can shield organisms, so clearer water disinfects better.