Standard Article


Municipal Water Supply

  1. National Drinking Water Clearinghouse

Published Online: 15 JUL 2005

DOI: 10.1002/047147844X.mw1803

Water Encyclopedia

Water Encyclopedia

How to Cite

National Drinking Water Clearinghouse 2005. Filtration. Water Encyclopedia. 1:227–230.

Publication History

  1. Published Online: 15 JUL 2005


Filtration is the process of removing suspended solids from water by passing the water through a permeable fabric or porous bed of materials. Groundwater is naturally filtered as it flows through porous layers of soil. However, surface water and groundwater under the influence of surface water is subject to contamination from many sources. Some contaminants pose a threat to human health, and filtration is one of the oldest and simplest methods of removing them. Federal and state laws require many water systems to filter their water. Filtration methods include slow and rapid sand filtration, diatomaceous earth filtration, direct filtration, packaged filtration, membrane filtration, and cartridge filtration.


  • filtration;
  • permeable fabric;
  • porous bed;
  • rapid sand filtration;
  • diatomaceous earth filtration;
  • direct filtration;
  • packaged filtration;
  • membrane filtration;
  • cartridge filtration