The process of separating water from its impurities is called Water filtration. We are able to do this process by using water filters. There are many tools that can be used when doing this, physical barriers, chemicals, and biological processes. Filters are used for several things we do every day, drinking water, pools, and irrigation.

There are many different types of common filters. There are media filters, which use sand to filter water as it moves from below the rock and sand to the surface. Screen filters, which utilize a screen that separate fine particles out of the water for irrigation among other things. Disk filters are the main water filters for irrigation. It is much like the screen filter, but instead of a screen it uses small disks stacked on top of each other in order to separate the impurities.

When raw water is in need of treatment slow sand filters can be used. They are usually a length of one to two meters deep. A layer of earth, called the Schmutzdecke layer, which uses bacteria and fungi to purify the water. Using this process exceptionally clean water is left on the surface of the earth.

Rapid sand filters or rapid gravity filters are forms of filtration used municipal water treatment facilities. Coarse sand is used to remove the particles that were previously trapped in flocks by salts of aluminum or iron. The simplest filter still in use today is the cloth filter. This filter can be dangerous because it is not very effective. It is done by using a folded cloth placed in a container. The container is dipped in water and then raised. The cloth is lifted from the container and the filtered water will move through the cloth and into the container.

There are forms of filtration that do not involve physical screens to filter the water. Ultra violet rays can be used as a way to filter water. Exposing water to ultra violet rays can remove all viruses and bacteria. It is usually used in raw water applications but has an increasing use in filtering drinking water. New York has already improved the construction of a drinking water disinfection facility that will be capable of producing two billion gallons of water a day.

Reverse osmosis is a filtration process that uses applied pressure to force a solution through a membrane that traps the solute and allows the solvent, in this case water, to pass move through to the other side. Most of the separation occurs in the outer layer in the polymer matrix. This filtration process requires a great amount of pressure to be forced on one side of the membrane. The membrane is known as semi permeable, which means is only allows the passage of the solute and not the solvent.

Catalytic converters are devices using filtration for the benefit of the environment instead of strictly humans. The converter is put on automobiles in order to reduce toxic emissions into the environment that are made by the vehicle.

Water filters are one of the most important devices man has ever invented. Primitive forms of these filters allowed man to survive in the harshest of climates. There will never be a time that people are not in need of water filters as a means of survival. Further research into this filtration can only prove itself worthwhile and beneficial.