Comparisons
 

Technologies Available

There are only five government accepted forms of water purification technologies available: UV Light, Carbon Filtration, Distillation, Reverse Osmosis, Chemicals

 

  Ultraviolet Light     

Carbon Block

Atmospheric Generation

A newcomer to the water field, these systems combine advanced technologies from several old fields to absorb moisture from the air and then purify it using carbon blocks and UV lights. These systems can provide the purest, safest and best tasting water anywhere on the planet.

 

Ultraviolet Light

Ultraviolet light systems make use of the ability of the UV portion of the light spectrum to kill bacteria. Such systems are the most effective available on bacteria, viruses and most algae with a <99.999 kill rate. The lights are normally combined with carbon technology to give more complete purification because particles in the water like dirt, leaves, etc. can prevent the disinfection process from hitting every bacterium, etc.; some can slip through in cases of heavy silt and sediment levels. 
  • These units should be used in conjunction with carbon or RO filters.

Solid Carbon Block Filters

This technology has combined the incredible adsorption capability of carbon with the ability of a solid brick of material to selectively strain out particles from water forced through it. The density of the brick determines how finely the water is cleaned. The better brands of this type of filter have a three part filter and are designed to prevent any possibility of "bypass" due to high pressure failure.

The following list of features are what combine to create the type of filter that will remove the widest range of possible contaminants in the drinking water:

  • Mechanical straining: the block of carbon mechanically strains out dirt, sediment, rust, algae, cryptosporidia, asbestos and particulate matter. This is all accomplished by water pressure so no electricity is required -- such a filter even works on a simple hand pump in emergencies!
  • Chemical bonding: As explained earlier, activated carbon bonds to thousands of chemicals. In fact, carbon will bond to most chemicals known to man! When water is forced through the solid carbon block, it is forced to slow down and increase the contact time with the carbon, allowing the carbon bonding to take place to reduce certain chemical pollutants like toxics, pesticides, THM's, chlorine, bad tastes, odors, etc.
  • Health-providing trace minerals like dissolved calcium and magnesium do not bond to carbon and are allowed to pass through, thereby retaining the health quality and good taste of the water.
  • Heavy metals like lead are adsorbed (or collected) by the carbon.
  • Prevention of bacterial growth: Most bacteria are strained out and remain on the outside of the carbon block. Therefore, because of the density and lack of oxygen and space inside the block, bacteria cannot breed in the medium and come out in the finished water.
  • Convenient: This type of system provides healthier filtered water on demand so there is no storage, nor running out at inconvenient times, no ordering bottles or picking bottles up from the store.
  • Inexpensive: This type of filter is a replaceable, self-clogging cartridge that lasts eight to 12 months (dependent on amount of sediment and dirt). The cartridge is designed to be replaced in minutes at home by the homeowner, just like screwing in a new light bulb. The cost of the units are relatively inexpensive -- over a ten-year period, the cost of the unit plus maintenance works out to a mere sixty bucks a year!! The cost of the water itself is from four to 8 cents per gallon. The units themselves are generally very easy to install and are designed to be a 45 minute installation for the handy homeowner or plumber. They can also be connected with refrigerators that have automatic icemakers and water dispensers so that all the water that a household consumes is filtered!

     

    The only drawbacks to solid carbon block systems is they do not kill all viruses and bacteria and should be used in conjunction with UV technology. They will also not remove nitrates or sulfides (byproducts of agricultural fertilization), and in these cases RO technology can take care of the problem. Nitrates and sulfides are found in relatively few areas however, so most consumers do not need to worry about them.

 

Granulated activated carbon

Carbon is a substance that has a long history of being used to absorb impurities and is the most powerful absorbent known to man. One pound of carbon contains a surface area of 125 acres and can absorb thousands of different chemicals. For centuries, sailing vessels used it to store drinking water for long voyages. Carbon is also commonly used as an effective antidote for swallowed poisons.

Activated carbon is carbon which has a slight electro-positive charge added to it, making it even more attractive to chemicals and impurities. Loose granular activated carbon (GAC) is used extensively in most of the commonly encountered water filters today. Most of these filters have ratings as simple taste and odor filters or as pre-filters designed to remove initial dirt, rocks, sediment, etc. Very few of these GAC filters are effective at true filtration (i.e. removal of substances of health concern). Below are some problems:

  • Channeling: When water is forced through a substrate of GAC (which has the consistency of sand or coffee grounds) it takes the path of least resistance and makes its own channels through the GAC in the filter. What this means is that the water being filtered is notcontacting the GAC for enough time to allow complete absorption of impurities to take place. Many impurities seep through along with the "filtered" water.
  • Bacterial growth: When the water passes through the GAC, some bacteria (primarily heterotrophic) are trapped in the substrate, too. The problem is that these trapped bacteria multiply prolifically in the warm, moist oxygen-containing environment among the grains of GAC. Because the GAC is loose, there is no barrier to keep any bacteria growing inside the filter from coming out with the water pushed through each time the filter is used. There have been extensive tests showing certain filters have thousands more bacteria coming out of them than initially went into them! Some companies add silver nitrate, a known poison, to the GAC to aid in keeping the bacterial growth down, but this method has limited effectiveness. There are also serious questions about adverse health effects from the silver nitrate itself!
  • Effectiveness decreases rapidly: Because the amount of GAC is usually minimal in most GAC filters, they quickly become saturated and overwhelmed with normal household usage. The filters must be changed quite often, which also adds to the expense of filter maintenance.

 

Distillation:

Distillation is an expensive process that heats the water to the vapor point and aids in removing some impurities from the water. The theory is that chemical pollution and other contaminants will be vaporized and separated off from the vaporized water. The treated water then passes into a holding tank and the drinking water is drawn from this tank as needed. The process itself requires electricity and adequate water, since it wastes gallons of water for every gallon produced.

Distillation is used in rare situations where large amounts of trace minerals (i.e. calcium, magnesium, etc.) must be removed from the water to improve the taste. Some people periodically drink mineral-free water for specific health regimens such as the dissolving of kidney or gall stones.

Other problems with distillation are:

  • Maintenance: the units require periodic and extensive maintenance to the piping that usually can only be done by the factory.
  • Holding tank: all distillers require a holding tank to store the processed water, inviting possible recontamination and bacterial growth in the tank.
  • Incomplete purification: distillation is not effective at removing the VOC's because many of them re-condense back into liquid just like the water does. For this reason, the distiller is usually combined with a granular carbon filter to remove additional chemicals that slip through.
  • Environmental contamination: in some cases, distillers have been shown to blow vaporized contaminants out into the surrounding air of the household.
  • Inconvenience: with most distillers, the homeowner has to wait eight hours to get a couple of gallons of drinking water.

 

Reverse Osmosis

Reverse osmosis, or RO, is another separation process that makes use of a semi- permeable membrane. This membrane lets particles of a certain size or smaller through and keeps back larger particles.

Like distillation, some contaminants can make it through the membrane just like water molecules, so a GAC filter is added at the end of the process to capture these materials. RO systems also waste three to 10 gallons of water for every gallon produced.

Unlike distillation, RO units leave the water well-oxygenated so that the water taste is much closer to that of "spring water." The distilled water always tastes flat and "lifeless." In cases of extreme mineralization or high nitrate levels in the water (agricultural areas), RO units are for the most part the systems of choice.

KDF Resin

KDF resin is a limited technology that is mainly used for chlorine removal. A large amount of the KDF and a long contact time with the water is needed to do the job. Therefore, this resin is best used in large commercial applications such as boiler systems although it is also used effectively in some showerhead filters.

Typically, KDF filters use zinc and copper to create electrolysis that helps keep bacterial growth down inside the filter. However, the systems using KDF may have problems with that zinc and copper leaching into the water they dispense.

KDF filters also tend to clog quickly (around six months in some cases) and this clogging action is dependent on specific water chemistry like pH and temperature. Companies using KDF recommend to backwash the filters (use hot water to dislodge trapped contaminants) but this method wastes many gallons of hot water, and has no way to prevent dislodged pollution from continuing out with the supposedly purified water.

Ozonation

Ozone units super-oxygenate water which kills bacteria with adequate contact time. Again, this is a process that only addresses bacterial contamination and so is necessarily combined with carbon filtration to be most effective.

Other drawbacks are:

  • Expensive to purchase and maintain
  • Ozonated water can contain high amounts of toxic contaminants, such as formaldehyde, formalin and different aldehydes. Some of the created by-products also allow for increased bacterial growth in the pipes down the line which contributes to re-infection of the water.
  • Create by-products in the treated water:

 

Bottled Water

Bottled water enjoys a booming business lately due to all of the water problems covered before. People drink it because of the improved taste, and that allows them to drink more water. The bottled water industry is required to test for the same group of contaminants as the public water utilities. The public water utilities are allowed to have a minimum contaminant level - bottled water companies are also allowed to sell water with a minimum level of contamination (bacteria, algae, dirt, lead, etc.). When the water tastes better, the public perceives it as purer. What people don't realize is that many times the bottled beverage is no purer than the water coming from the kitchen tap, often worse - it just tastes better!

Here is the scoop on bottled water:

  • Expensive: The California Assembly Office of Research did a study on bottled water in 1985 that showed consumers paying up to one thousand times the cost of tap water for bottled water.
  • Inconvenient: People who use bottled water regularly tend to have lots of bottles around underfoot -- empty containers or new jugs waiting to be used. These people usually hoard the "clean" water for special purposes, i.e. coffee, beverages, rather than use it freely whenever needed. There is always the problem of having too many bottles on hand because they are not used fast enough, or not enough bottles because the water is being consumed more quickly.
  • No laws requiring it to be purer than tap water: In 1991, the U.S. House Energy and Commerce Commission did a study on bottled water with the following findings:
    • 25% of "gourmet" waters (i.e. Evian, Perrier, et al) draw from the same sources as cities!!
    • 31% exceed tap water limits for microbiological contaminants!
    • 25% could not document their water sources!
    • Any bottled water sold strictly within state borders is not subject to regulation by the Food and Drug Administration!
The University of Delaware found that of the 37 popular mineral waters, at least 24 were out of line with at least one of the 31 standards set for drinking water! The California Assembly Office of Research study (1985) also did random samplings of bottled waters sold in California (name brands such as Alhambra, Black Mountain, Sparkletts, etc.) and found numerous reported contamination problems, such as finding various chemicals, insects, algae, bacteria, fingernails and even chewing gum!

Because of the nature of the bottling and handling process, it is difficult to avoid casual contamination from different points in the process. Air that bubbles up into home drinking water dispensers is laden with bacteria and dust that contaminates the water each time. Bottled water companies recommend keeping the water out of direct sunlight and even supply covers for the bottles because the algae, etc. that was not filtered out completely will start to grow in the bottle with warmth and light (remember the greenish scum?)!

Chemical Additives

For years major metropolis areas have routinely used chemical additives to purify their water systems. Today governments and health professionals are starting to understand the negative health effects that these chemicals put on the human body. So the race is on to provide clean safe water without them or to remove them at the point of use before we drink the water.