Mechanical Filtration
This is nothing more than having a barrier perforations smaller than the contaminant you want to remove. This process of filtration removes tiny particles that are suspended in the water such as dirt, silt, sand, sediment, rust and additional un-dissolved particles.  As water passes through the media the elements are held or blocked and effectively taken from the water. Nothing too high-tech about that.

Depending on the quality and/or style of the filtration medium, matter as small as 0.5  microns can be taken from your drinking water. For reference purposes, a micron is equal to 1/25,000 of an inch, the diameter of one strand of your hair is about 100 microns.

A variety of substances are used to produce mechanical filtration media. Ceramics and various resins make up the majority of mechanical water filtration.

Oxidation-Reduction Process or Redox
Redox is a process whereby electrons of one molecule are passed on to another. That is to say that where you blend two unlike metals you induce an electrochemical process that oxidizes a host of chemicals frequently found in ground water along with our civic water supplies, consequently taking them out of your water. The heavy metals like lead, chromium, aluminum and cadmium are removed by the electrochemical process. These metals are attracted to the filter’s media, much like to a magnet.

KDF Fluid Treatment, Inc., produces the most widely used media of this kind, a copper and zinc alloy, and has retained the patent ever since 1987.

Adsorption: Activated Carbon
Activated carbon soaks up organic contaminants and substances that can make your water smell and taste bad. Not to mention it has the ability to remove chlorine and its byproducts and pesticides which, of course, are bad for you. This material is very porous having a vast surface area, so much so that the carbon in a common countertop filter could have a surface area of around 200 football fields.

The term “activated” refers to a procedure by which the carbon is made more porous than it is naturally. Activation is achieved with steam, chemicals or by controlled manufacturing processes while creating the carbon.

Activated carbon works like this: When water flows through the filter dissolved chemicals adhere to the carbon letting the water to continue. Essentially this is the same way a sponge works which is why it’s referred to as absorption.

Now that you are clear on how carbon works in a water filter let’s talk about the three categories activated carbon fall into: granulated activated carbon (GAC), carbon block (CB) and powdered activated carbon (PAC). The Carbon Block requires more water pressure but also can remove more contaminants and lasts longer. On the other hand granulated activated carbon is less expensive and is a suitable choice when used with municipally supplied water. The PAC variety is not used in residential applications as often.

Some of the types of material used for manufacturing activated carbon are wood, coal, lignite, coconut shell. Coconut shell is considered the premium choice when making filtration systems for drinking water because of its penchant to enhance the flavor of the water, leaving a “sweetness” to it.

Please understand that water filters do not wholly eliminate contaminates, they can only lessen them. Nevertheless a high-quality filtration system is going to strip the majority of the undesirable contaminants it is designed to remove. Make it a point to buy just water filters certified by the National Sanitation Foundation (NSF). These filters are going to have been tested to verify the manufacturer’s claims. In other words you can be sure of what you are purchasing.

There are really only a few methods of water filtration: Mechanical filtration works like a sieve removing that is bigger than the holes. Absorption works when the chosen media attracts a contaminant causing it to stick to the media’s surface. Redox or Oxidation-Reduction removes contaminants through an electrochemical process that oxidizes, or changes, the unwanted chemical to an inert state. So when researching water filtration brands keep these in mind and be sure you understand which method the media uses and what it is capable of removing.

It is also important to know what contaminants, if any, are in your water. A water testing kit, or even better a water testing lab, can give you insight into what type of purification system you should be looking for.

Now that you know what is in your water it is important to understand what should be removed from your water. Here there is much controversy. The EPA will tell you that lead is okay up to 15 ppb. That does not seem like much but do you want any lead in your water? For fluoride the EPA says that the acceptable limit is 4 mg/L for adults and 2 mg/L for children under 9. How can they have two different action levels? Which does your municipal water supply follow? As you can see our government agency that is suppose to protect us is not clear on whether fluoride should be in our water. Just a minimal amount of research will have you rushing out to get the best fluoride water filter you can find! I digress.

It is my opinion that with water filtration it is best to err on the side of caution and clean up your drinking as much as you can. Some filtration methods do remove minerals the body uses and needs, however the amount removed is minimal compared to the concentrations of the contaminants left in.

Next you need to decide at what point you want to filter your water. Essentially your choices are at the source, which would be where the water comes into your home, or point of use such as kitchen or shower faucets. The advantage to the whole house approach is you have less to mess with and replace. However it is more expensive and your house plumbing can leach chemicals into your water which would still require a drinking water filter. Point of use filtration is generally much more easy to install and you can choose where you spend your filtering dollars. At a minimum I would recommend an under sink or countertop water filter for drinking and a shower water filter for bathing

Now that you have figured out where you are going to install your filtration system you are ready to start looking at brands. There are literally dozens of brands to choose from but it does not have to be terribly confusing. Just watch out for the following few indicators to help you decide which water filter brand suits your needs the best.

The primary thing to look for is the NSF (National Sanitation Foundation) certification. You probably recognize the their symbol. The NSF have been creating and instituting independent programs for testing products for a long time. They not only test the water treatment systems made but they also evaluate manufacturing methods and do yearly surprise spot checks on the water filter brands they certify.

Another thing to look for is a water filtration system that meets the California guide lines for water filtration. California has laws against unverifiable claims of water purification. If a manufacture has gone to the trouble and expense to sell in California then you are probably getting a pretty good system.

Lastly look for a minimum of a 3 year warranty for your water filter system. Generally the longer the warranty the better the filter. However be sure you read the warranty so that there are not any surprises.