Home Water Filter Shortcoming #1 – Activated Carbon

In the near future Glanris, Inc., will be releasing a new brand of home water filters offering technology and engineering never before offered in any home water product. Pretty big claim, yeah? Well stay tuned and be wow’d. In the meantime, let’s take a closer look at why your home filter never seems to deliver as it is advertised.

The first shortcoming of home water filters is Granular Activated Carbon or GAC. Made from the high temperature (1500 º C) charring of coconut shells, GAC has long been a staple of water treatment. It is an excellent media for removing chlorine compounds, however that very feature presents some problems. Once chlorine has been removed from water, bacteria, viruses and other organisms will grow rapidly in the filtered water. While you may enjoy the taste of water sans chlorine, if your water stands for any period of time there is a good chance you will be drinking bacteria.

Also, GAC itself is a very good substrate for bacteria to grow on. So much so that in the food, beverage and pharmaceutical industries GAC filter machines are routinely sanitized with steam/hot water several times a day. In home filters, some products impregnate the GAC with silver particles which do a good job of keeping bacteria from growing on the filter. Still, bacteria will indeed grow in all water that has no chlorine. So be vigilant about understanding what you are filtering your water with.

Another shortcoming of GAC that few filter manufacturers will tell you is that these media are only efficient in a really narrow temperature range, generally if your water is not 60 – 80 °F GAC doesn’t work optimally. At colder temperatures the exchange kinetics slow down. At higher temperatures many of the contaminants previously adsorbed onto the GAC will actually slough off and wind up in your drinking water.

Finally, the global supply of charred coconut shells is widely known to fluctuate greatly in performance and quality dependent on the area grown, how it is processed, and the quality of the raw coconut shell material.

Now, don’t panic. Your home GAC water filter is largely safe, but it is also largely old technology that is not the panacea it once was thought to be. Next up, we will look at the shortcomings of another commonly used drinking water purification technology called ion exchange. Stay tuned!