To effectively remove pollutants, water filters primarily use two different methods.
- Physical Filtration:
Water passes through the screen ultimately producing clean water by sifting it through a membrane. This is a simple process which removes larger impurities by physically screening them out.
2. Chemical Filtration: To remove smaller impurities that physical filters leave behind, chemical filtration utilizes a chemical reaction by placing the water in contact with an activated material like carbon.
Because there are various types of filters, it is vital to know if the one you need will meet your individual needs. To help discern that filters approved function, there are standard Certification Rating assigned, including; NSF/ANSI Standards 42, 53, 58, and 177, details which can be found here: https://watertera.com.
Commonly, consumer-grade filters like “whole-house” or under-sink water filters use activated charcoal to achieve this. These granules of carbon are produced when oxygen starved wood is burned, and it is remarkably porous yet fine, with a large internal surface area, making it great at catching particulates and holding on to them as water passes through. Furthermore, “activated” carbon possesses a positive charge causing it to attract those impurities and hold them.
Frequently these household water filters will employ both methods to clean tap water, in two or more stages. The larger impurities are caught by the physical filter’s membrane, which helps protect the carbon filter when it catches the smaller contaminants. These smaller impurities include chemicals like chlorine, benzene, and radon, however they are not very helpful when it comes to inorganic impurities like copper, barium, or fluoride. Unfortunately, viruses are also not filtered by carbon, as they simply too small to be caught. However, these filters can remove some rather hazardous microorganisms, like Cryptosporidium and Giardia.
Viruses are often removed via ultraviolet disinfection, a process that involves passing the water through channels that are exposed to high levels of ultraviolet light radiation. Effectively, this process sterilizes bacteria and viruses, however it does require energy to produce the radiation, and units are more expensive than traditional activated charcoal water filters.
An alternative to ultraviolet sterilization is to simply boil your water. This process is called Pasteurization and it kills organisms like viruses, bacteria, and protozoa by damaging their “structural components”, according to the State of NY’s Health Resource found here: https://www.health.ny.gov. Please note that is recommended to boil your water for at least 1 minute for this effect to take place and it does not remove any particulate contaminates like silt.
Consider your options and weigh your risks when choosing a water filter for home use. There are many available to consumers at various price points and no one filter will be “best” for all applications, so choose the one that is best for you and your health.
You can always have your water tested, as well. Many companies provide this service to their clients free of charge and you can also find tester kits in the big box stores and online.