How Do Water Filters Work?

How Do Water Filters Work?

Posted by Dan B. on Aug 8th 2016

Water is a basic necessity of life but drinking dirty water can be deadly. Every year 6 million deaths are attributed to waterborne diseases. There are various methods of water treatment but using a water filter is the safest and easiest way to keep your water clean.

There are two classes or types of water filters based on how they filter; Size Exclusion and Absorption.

Size Exclusion uses a "round hole, square peg" method. As a square peg will not fit into a round hole size exclusion prohibits contaminants from passing through the filter by using smaller holes than the size of the contaminates. Imagine trying to push a basketball through a garden hose. The diameter of the hose is too small for the basketball to fit. The pore size or hole size of a filter using size exclusion is large enough to allow water through but small enough to keep contaminants such as E.coli giardia or viruses from entering the filter.

Pore size is measured in microns. Any filter with a pore size or 0.2 microns will filter bacteria and protozoa. To be considered a purifier and be able to filter viruses the pore size needs to be 0.01 microns or smaller. The smaller pore size will provide more protection but will also decrease the flow rate of the water. Most filters with a pore size of 0.01 microns are "drip" filters or require a pump to pressurize the water to increase the flow rate.

The two most common filtration mediums using size exclusion in water filtration are hollow fiber membrane and ceramic filters.

Absorption works by attracting the chemicals and contaminates at a molecular level and trapping them in the filter medium. Like a strong magnet, filters using absorption attract and hold on to contaminants while allowing clean water to pass through the medium. Using absorptive filter are the only way to remove chemicals bad taste and bad odor from water. The one downside to absorptive filters is that they can fill up. There is only so much a magnet can pick up before it cannot pick up any more. These types of filters need to be replaced more often than filters using size exclusion.

A common medium that uses absorption is Activated Carbon. You can find activated carbon in most pitcher filters, refrigerator filters and in the Oasis.

The Oasis is comprised of modules filled with various filter mediums using both size exclusion and absorption. The modularity of the Oasis allows you the ability to customize what filter mediums you are using and when.