I’ve spent quite a bit of time researching how to filter drinking water effectively. Originally, I was interested in filtering the rainwater that falls on my roof. But I had to put that project on the back burner for now. During my research I noticed that there is little unbiased information available on water filters and filtration techniques.

Update: I discovered a good book on the subject of drinking water filtration: The Drinking Water Book. The author, Colin Ingram, includes a comprehensive collection of water filter reviews. He rates filter from “Acceptable” to “Excellent”. See our review The Best Water Filters Of 2009 for more information.

I like clean tasting water, and pure water is quite important to one’s health. Filtering your own water at home is really the most effective way of ensuring good water quality. As you may know, bottled water is extremely inefficient, and tends to be of lower quality than municipal tap water. However, tap water often picks up contaminants on its way through the pipes to your house. But with proper filtering, it can be made quite pure.

There are six types of contaminants you want to remove from municipal tap water:

Chlorine and chloramines Volatile Organic Compounds (pesticides, herbicides, etc.) Heavy metals (Lead, Mercury, Aluminum, Cadmium, Chromium, Copper) Bacterial and viruses (Giardia and Cryptosporidium) General Sediment Fluoride

In terms of personal health, chlorine and VOCs are the most toxic contaminants commonly present in municipally treated drinking water.

You can remove most of these contaminants using water filters (except for fluoride and MTBE, but more on that later). There’s really no need for elaborate filtration systems like reverse-osmosis or distillation. These systems are expensive, and they are not needed when filtering tap water, plus they also remove useful minerals from the water and give it a “flat” taste due to the lack of minerals and oxygen. Moreover, the distillation process does not remove VOCs in the water.

There are a lot of water filters out there, and most will do their job reasonable well, but only if they are replaced every six months, and this can be quite costly (I’ll let you know about less expensive filters below). The editors at ConsumerSearch.Com compiled water filter reviews from various magazines, and the consensus seems to be that Pur brand are the best faucet-mount filters and pitcher filters, and Whirlpool has the best whole-house filters.

NSF International certifies water filters — this certification ensures that the filters do their job, and do not re-contaminate the water with bacteria. Most filter manufactures will advertise that their filters are NSF certified. However, many commonly available filters will let quite a few contaminants through. For example, granular filters do not utilize the chemical adsorption process, allowing several contaminants to pass through. Likewise, rapid water filters do not give the water adequate contact time with the filter media, limiting the number of contaminants that may be removed. For example, in-fridge or faucet-mount filters may not filter VOCs and chlorination by-products like Trihalomethanes (THMs). Generally, slow filtration tends to be best. Drip filters will remove a wider range chemicals, pesticides and MTBE (a gasoline additive).

In my home, I use a British Berkefeld drip filter, which is made by Doulton (pictured above). I like drip filters because they provide great quality filtration, and they are inexpensive to use, because they only need to be replace every six months. You can clean them with a stiff brush if they become dirty with sediment. To use a drip filter, you pour tap water in the top, and the water slowly drips through the filter to the bottom compartment. The process takes a couple of hours.

My Berkefeld drip filter contains two SuperSterasyl self-sterilizing ceramic elements. The elements are made with diatomaceous earth (a silica-like sediment originating from kiesel algae), silver and activated carbon. It’s important to have self-sterilizing elements because they can easily become contaminated with bacterial, especially while cleaning them. The sterilization is achieved by impregnating the filter with silver.

Another good ceramic drip filter is made by Stefani (pictured above). I like their French Provence inspired design. The filters are manufactured in Brazil, and the units are hand made by local clay potters. The clay cools the water, due to an evaporative cooling effect. These filter remove 95% of chlorine, pesticides, iron, aluminium and lead; and 99% of cryptosporidium, guardia and sediment. The filters lasts six months or 300 gallons. Stefani filters are available at Amazon.

Let’s address some the contaminants that can only be removed using specialties filters: fluoride, arsenic, and MTBE. These special filters are typically added in series to a standard water filter.

Fluoride is commonly added to municipal water in the U.S. The reason given is that it supposedly improves the health of children’s teeth. However, many people (including me) would rather not have fluoride in their drinking water, for a variety of health reasons. The Fluoride Action Network has a lot of relevant information on this topic. Fluoride is actually quite difficult to remove from water, almost all water filters will not remove it. It can be removed with an “activated alumina” filter. Doulton and other companies offer activated alumina filters.

MTBE (a gasoline additive) has contaminated much of the groundwater in the U.S. In drinking water, even trace amounts of MTBE can cause taste and odor problems. The potential long-term health effects of MTBE are not understood at this time, however, initial studies indicate MTBE may cause kidney and liver problems. You can remove MTBE using a specialty filter, for example this one.

Arsenic is another common contaminant that can only be removed at significant levels using a specialty filter. For more information about arsenic in drinking water see this page. Filtration through activated carbon (which many water filters use) will reduce the amount of arsenic in drinking water from 40 – 70%. Anion exchange filters can reduce it by 90 – 100%

More information can be found in The Drinking Water Book.