Truth in advertising:     The importance of independent certification for product evaluation There are many thousands products on the market that claim to provide you with the purest water available, everything from filtration systems and distillation units to bottled water. There are, for example, over 2,500 different water filters on the market. How do you evaluate competing, often contradictory, statements and determine which claims are accurate and which advertisements are nothing more than creative writing. When purchasing health related products, creative advertising can be expensive for the consumer, not to mention downright dangerous.  An improperly maintained water filter can actually incubate trapped bacteria and release them into the "filtered" water.   I personally believe that a product's performance as well as the accuracy of its advertising literature should be tested and certified by an independent and disinterested third party.  If a product is certified by a reputable company you can be assured that a product's ads are not misleading and the product will perform as specified.   Two organizations provide independent certification for water purification devices, NSF International and the Water Quality Association (WQA).  The WQA has developed a Gold Seal program to help consumers choose quality water treatment products.  The WQA tests prototype water treatment equipment, and awards the Gold Seal only to those systems that have met or exceeded industry standards for contaminant reduction performance, structural integrity, and materials safety. NSF International is a group that certifies water treatment systems, distillation units, bottled water, water softeners, and a number of other food preparation systems.  NSF certification means that not only do the products perform as tested, the product advertisements are also evaluated for accuracy and truthfulness.  Products are tested on an ongoing basis to make certain that companies continue to produce products that perform as advertised. You need to be aware that there are a number of different NSF standards and different levels of compliance within the standards. NSF certification does not mean much unless you know exactly what  a specific certification standard stands for. A water filter certified to meet NSF Standard 42 Class II for taste, odor and chlorine and Class II for particulate matter is not equivalent to a filter certified to meet NSF Standard 42 Class I for taste, odor and chlorine and Class I for particulate matter and Standard No. 53 for Health Effects.  The latter filter will remove a far wider range of contaminants -- and will also probably cost 10 times as much as the former. You will also find, if you research water purification devices or bottled water, that many companies state on their literature "Tested to NSF standards".  Tested by who?  How often?  Who backs up that claim?  I just visited a web site that advertised their water filter as tested and certified in accordance with NSF/ANSI standards 42 and 53 (the NSF logo was even displayed).  I then checked the NSF on-line site and neither the company nor the filter was listed as certified. Unfortunately, there are even a few pitfalls to interpreting the certification reports - one of the things to be aware of is what I call "padding the list".  Some companies “play the certification game” by  paying separately to have individual VOCs tested and listed, even though, if the VOC Reduction group is listed, all of the individual VOCs on the NSF table below are already covered and do not normally need to be re-listed. Check out the NSF site below, and use them as one of your guides to selecting a reliable product. The site has on-line comparisons of many of the products they certify. NSF International Mission statement - Behind the NSF Mark is an independent, not-for-profit organization called NSF International. For over 50 years NSF has been committed to public health safety and protection of the environment by developing standards, by providing education and by providing third-party conformity assessment services while representing the interest of all stakeholders.  The NSF site provides an on-line comparison of water filtration units and bottled water products that are certified by NSF: Selecting a Household Water Treatment System & Drinking Water Fact Kit You can review certified Drinking Water Treatment Units. The NSF Standards that apply to water filters are # 42 and # 53. To use the guide, for water treatment units, either enter a company name you are interested in investigating or scroll to the bottom of the page and select either the product type (counter top filter, under counter filter, etc.) or the product standard (42, 53, etc.). You can look up certified bottled water products by brand     name, product type, etc. at Bottled Water and Packaged Ice. NSF Drinking Water Standards There are currently six ANSI/NSF standards relating to water filtration and treatment devices, each one designed for a specific type of product.    STANDARD 42: Drinking Water Treatment Devices - Aesthetic Effects    STANDARD 44: Cation Exchange Water Softeners    STANDARD 53: Drinking Water Treatment Devices - Health Effects    STANDARD 55: Ultraviolet Microbiological Water Treatment Systems    STANDARD 58: Reverse Osmosis Drinking Water Treatment Systems    STANDARD 62: Drinking Water Distillation Systems

Boiling: In an emergency, boiling is the best way to disinfect water that is unsafe because of the presence of protozoan parasites, bacteria or viruses. If the water is cloudy, it should be filtered before boiling.  Filters designed for use when camping, coffee filters, towels (paper or cotton), cheesecloth, or a cotton plug in a funnel are effective ways to filter cloudy water. Place the water in a clean container and bring it to a full boil and continue boiling for at least 3 minutes (covering the container will help reduce evaporation).  If you are more than 5,000 feet above sea level, you must increase the boiling time to at least 5 minutes (plus about a minute for every additional 1,000 feet).  Boiled water should be kept covered while cooling.  The advantages of Boiling Water include: Pathogens that might be lurking in your water will be killed if the water is boiled long enough. Boiling will also drive out some of the Volatile Organic Compounds (VOCs) that  might also be in the water. This method works well to make water that is contaminated with living organisms safe to drink, but because of the inconvenience, boiling is not routinely used to treat drinking water except in emergencies. The disadvantages of Boiling Water include: Boiling should not be used when toxic metals, chemicals (lead, mercury, asbestos, pesticides, solvents, etc.), or nitrates have contaminated the water.  Boiling may concentrate any harmful contaminants that do not vaporize as the relatively pure water vapor boils off.   Energy is needed to boil the water, so it may be difficult to boil water in an emergency.

Distillation: To remove impurities from water by distillation, the water is usually boiled in a chamber causing water to vaporize, and the pure (or mostly pure) steam leaves the non volatile contaminants behind. The steam moves to a different part of the unit and is cooled until it condenses back into liquid water.  The resulting distillate drips into a storage container.  Salts, sediment, metals - anything that won't boil or evaporate - remain in the distiller and must be removed.  Volatile organic compounds (VOCs) are a good example of a contaminant that will evaporate and condense with the water vapor. A vapor trap, carbon filter, or other device must be used along with a distiller to ensure a more complete removal of contaminants. The advantages of Distillation include: A good distillation unit produces very pure  water.  This is one of the few practical ways to remove heavy metals,  nitrates, chloride, and other salts that carbon filtration can not remove.  Distillation also removes pathogens in the water, mostly by killing and leaving them behind when the water vapor evaporates.  If the water is boiled, or heated just short of boiling, pathogens would also be killed. As long as the distiller is kept clean and is working properly the high quality of treated water will be very consistent regardless of the incoming water - no drop in quality over time. No filter cartridges to replace, unless a carbon filter is used to remove volatile organic compounds. The disadvantages of Distillation include: Distillation takes time to purify the water, It can take two to five hours to make a gallon of distilled water.; Distillers requires periodic cleaning of the boiler, condensation compartment, and storage tank.  Countertop Distillation is one of the more expensive home water treatment methods, using $0.25 to $0.35 of electrical energy per gallon of distilled water produced - depending on local electricity costs.  The cost of ownership is high because you not only have the initial cost of the distillation unit to consider, but you also must pay for the electrical energy for each gallon of water produced. If it cost you $0.25 to distill each gallon, and you purified 10 gallons per week, you would pay $130 for your 520 gallons of distilled water each year. Most home distillation units require electricity, and will not function in an emergency situation when electrical power is not available.   You might want to check  NSF International to see if the distillation system you are interested in purchasing is certified. I have had a number of questions asking if distilled water (or water with most of the ions removed by reverse osmosis or deionization) are either bad for a person's health or beneficial for health relative to purified water that still contains ions (usually calcium and magnesium).  Click here to view my response to that question.

Reverse Osmosis (RO): Water pressure is used to force water molecules through a membrane that has extremely tiny pores, leaving the larger contaminants behind. Purified water is collected from the "clean" side of the membrane, and water containing the concentrated contaminants is flushed down the drain from the "contaminated" side.  The average RO system is a unit consisting of a sediment/chlorine pre filter, the reverse-osmosis membrane, a water storage tank, and an activated-carbon post filter.  They cost from about $150 to over $1,500 for point of use systems. The advantages of Reverse Osmosis include: Reverse osmosis significantly reduces salt, most  other inorganic material present in the water, and some organic compounds.  With a quality  carbon filter to remove any organic materials that get through the filter, the purity of the treated water approaches that produced by distillation. Microscopic parasites (including viruses) are usually removed by properly functioning RO units, but any defect in the membrane would allow these organisms to flow undetected into the "filtered" water - they are not recommended for use on biologically unsafe water.  Though slower than a carbon or sediment water filter, RO systems can typically purify more water per day than distillers and are less expensive to operate and maintain. Reverse Osmosis systems also do not use electricity, although because they require relatively high water pressure to operate, they may not work well in some emergency situations. The disadvantages of Reverse Osmosis include: Most point of Use RO units make only 12 - 24 gallons of treated water a day for drinking or cooking - which is ok for most homes since the treated water is stored in a tank for use.   RO systems waste water. Two to four gallons of "waste" water are flushed down the drain for each gallon of filtered water produced.   Some pesticides, solvents and other volatile organic chemicals (VOCs) are not completely removed by RO.  A good activated carbon post filter is recommended to reduce these contaminants. Many conditions affect the RO membrane's efficiency in reducing the amount of contaminant in the water.  These include the contaminant concentration, chemical properties of the contaminants, the membrane type and condition, and operating conditions (like pH, water temperature, and water pressure).  Although RO filters do not use electricity, they depend on a relatively high water pressure to force the water molecules through the membrane.  An electric booster pump can be used to increase water pressure if needed.  In an emergency situation where water pressure has been lost, these systems will not function. * However, if a high quality activated carbon filter is used for the post filter, it could be disconnected and used to siphon water through in an emergency to reduce many contaminants. RO systems require maintenance.  The pre and post filters and the reverse osmosis membranes must be changed according to the manufacturer's recommendation, and the storage tank must be cleaned periodically. Damaged membranes are not easily detected, so it is hard to tell if the system is functioning normally and safely. You might want to check  NSF International to see if the Reverse Osmosis system you are interested in purchasing is certified.  A reverse-osmosis system is a good treatment option for people who have unacceptably high levels of dissolved inorganic contaminants in their drinking water which can not be removed effectively or economically by other methods. Water from shallow wells in agricultural areas that contains high nitrate levels is a good example of a situation where RO would make sense. Most people, however, who are using municipal water water that is subject to EPA regulations usually have acceptably low levels of nitrates. Maximum nitrate levels should be able to be determined by requesting a water quality report from your local water provider. I have received a number of questions asking if distilled water is either bad for a person's health or beneficial for health relative to purified water that still contains ions (usually calcium and magnesium).  This question pertains equally well to water from a RO system, because most ions have been removed by the treatment. Click here to view my response to that question.

Water Filtration: The topic of water filters is complicated because there are so many models available (over 2,500 different models manufactured by more than 500 companies), and because there are so many types of filtration strategies and combinations of strategies used. The basic concept behind nearly all filters, however, is fairly simple. The contaminants are physically prevented from moving through the filter either by screening them out with very small pores and/or, in the case of carbon filters, by trapping them within the filter matrix by attracting them to the surface of carbon particles (the process of adsorption).     There are three main types of filters: Sediment and Activated Carbon filters are discussed below, and sometimes they are combined into a single unit.  The third type, Reverse Osmosis will be considered as a separate topic.   You will read about micron or sub micron filtration. This is a measure of how good the filter is at removing particles from the water - smaller is better. A micron is a unit of measure - one micron is about 1/100 the diameter of a human hair. A filter that removes particles down to 5 microns will produce fairly clean-looking water, but most of the water parasites, bacteria, cryptosporidia, giardia, etc. will pass through the pores. A filter must trap particles one micron or smaller to be effective at removing cryptosporidia or giardia cysts. Viruses can not be effectively removed by any filtration method.  In theory, reverse osmosis will remove viruses, but a small flaw in the membranes would allow viruses to pass undetected into the 'filtered' water. Click here too view a figure that compares the relative size of several biological contaminants with the pore size of some common filters.  A benefit of all home filtration systems is that they are passive. That is, they do not require electricity to filter the water, and normal home water pressure is used to force the water though the filter. The only routine maintenance required is periodic replacement of the filtration element. As long as the cost of the replacement filter elements is reasonable, owning a even a high-end water filter can be very inexpensive if you look at the long term costs and compare it with other solutions.. Sediment Filters - Solid Particles are Strained Out of the Water: Fiber Filters: These filters contain cellulose, rayon or some other material spun into a mesh with small pores. If you take    a piece of cloth and pour water containing sand through it you will get the picture. Suspended sediment (or turbidity) is removed as water pressure forces water through tightly wrapped fibers.  Some small organic particles that cause disagreeable odors and taste may also be removed.  These filters come in a variety of sizes and meshes from fine to coarse, with the lower micron rating being the finer. The finer the filter, the more particles are trapped and the more often the filter must be changed.  Fiber filters are often used as pre-filters to reduce the suspended contaminants that could clog carbon or RO filters. Fiber filters will not remove contaminants that are dissolved in the water, like chlorine, lead, mercury, trihalomethanes or other organic compounds. Ceramic Filters: Ceramic filters are much like fiber filters and use a process where water is forced through the pores of a ceramic filtration media. This provides  mechanical filtration only. This type of filter can reduce asbestos fibers, cysts (if the pores are one micron or smaller), some bacteria (with pore sizes in the 0.2 - 0.8 micron range**) and other particulate matter.  Ceramic filters will not remove contaminants that are dissolved in the water, like  chlorine, lead, mercury, trihalomethanes or other organic compounds, nor will they remove viruses. These filters may be used as a back-end to an activated carbon filter to provide a more thorough removal of contaminants. ** NOTE - NSF does not certify filters for bacterial removal, and I am unaware of any independent certification process for their removal. Activated Carbon Filters: Activated carbon (AC) is particles of carbon that have been treated to increase their surface area and increase their ability to adsorb a wide range of contaminants - activated carbon is particularly good at adsorbing organic compounds.  You will find two basic kinds of carbon filters Granular Activated Carbon (GAC) and Solid Block Activated Carbon (SBAC).  Contaminant reduction in AC filters takes place by two processes, physical removal of contaminant particles, blocking any that are too large to pass through the pores (obviously, filters with smaller pores are more effective), and a process called adsorption by which a variety of dissolved contaminants are attracted to and held (adsorbed) on the surface of the carbon particles. The characteristics of the carbon material (particle and pore size, surface area, surface chemistry, density, and hardness) influence the efficiency of adsorption.   AC is a highly porous material; therefore, it has an extremely high surface area for contaminant adsorption. One reference mentions " The equivalent surface area of 1 pound of AC ranges from 60 to 150 acres (over 3 football fields)".  Another article states, "Under a scanning electron microscope the activated carbon looks like a porous bath sponge.  This high concentration of pores within a relatively small volume produces a material with a phenomenal surface area: one tea spoon of activated carbon would exhibit a surface area equivalent to that of a football field." ( estimates of surface area vary from different sources - RJ) AC is made of tiny clusters of carbon atoms stacked upon one another. The carbon source is a variety of materials, such as peanut shells, coconut husks, or coal. The raw carbon source is slowly heated in the absence of air to produce a high carbon material. The carbon is activated by passing oxidizing gases through the material at extremely high temperatures. The activation process produces the pores that result in such high adsorptive properties.  An article about Activated Carbon states that "Activated carbon is one of the best tools which can be used to reduce risks to human health and provide an aesthetically pleasing product at reasonable cost."  The article also describes how AC works and has some of the best scanning electron microscope pictures of actual AC granules I have seen. The adsorption process depends on the following factors: 1) physical properties of the AC, such as pore size distribution and surface area; 2) the chemical nature of the carbon source, or the amount of oxygen and hydrogen associated with it; 3) chemical composition and concentration of the contaminant; 4) the temperature and pH of the water; and 5) the flow rate or time exposure of water to AC.  Interesting articles:  What is Activated Carbon, Adsorption, History of AC. The effectiveness of carbon filters to reduce contaminants is affected by the factors affecting adsorption listed above and three additional characteristics of the filter, contact time between the water and the carbon  material, the amount of carbon in the filter, and pore size. The length of contact time between the water and the carbon material, governed by the rate of water flow and the amount/volume of activated carbon, has a significant effect on adsorption of contaminants. More contact time results in greater adsorption.  The amount of carbon present in a cartridge or filter affects the amount and type of contaminant removed. Less carbon is required to remove taste- and odor-producing chemicals than to remove trihalomethanes.  Pore size characteristics will be discussed in greater detail on the GAC and SBAC pages, but GAC filters contain loose granules of activated carbon while in SBAC filters, the activated carbon is in the form of very small particles bound into a solid, matrix with very small pores. Because of the filter characteristics discussed above, the most effective Point of Use activated carbon filters are large SBAC filtration systems, and the least effective are the small, pour-through pitcher filters. Activated carbon filter cartridges will, over time, become less effective at reducing contaminants as the pores clog with particles (slowing water flow) and the adsorptive surfaces in the pores become filled with contaminants (typically not affecting flow rate).  There is often no noticeable indication that a carbon filter is no longer removing contaminants, so it is important to replace the cartridge according to the manufacturer's instructions.  The overall water quality (turbidity or presence of other contaminants) also affects the capacity of activated carbon to adsorb a specific contaminant. It is important to note, particularly when using counter-top and faucet-mount carbon filtration systems, that hot water should NEVER be run through a carbon filter. I have seen warnings about possible damage to the filter from hot water.  Perhaps more importantly, hot water will tend to release trapped contaminants into the water flow potentially making the water coming out of the filter more contaminated than the water going in. Granular Activated Carbon (GAC): In this type of filter, water flows through a bed of loose activated carbon granules which trap some particulate matter and remove some chlorine, organic contaminants, and undesirable tastes and odors.  The three main problems associated with GAC filters are: channeling, dumping, and an inherently large pore size.  Most of the disadvantages discussed below are not the fault of the activated carbon filtration media, rather, the problem is the design of the filters and the use of loose granules ofactivated carbon.   The advantages of GAC filters include: Simple GAC filters are primarily used for aesthetic water treatment, since they can reduce chlorine and particulate matter as well as improve  the taste and odor of the water. Loose granules of carbon do not restrict the water flow to the extent of Solid Block Activated Carbon (SBAC) filters.  This enables them to be used in situations, like whole house filters, where maintaining a good water flow rate and pressure is important. Simple, economical maintenance.  Typically an inexpensive filter cartridge needs to be changed every few months to a year, depending on water use and the manufacturer's recommendation.  GAC filters do not require electricity, nor do they waste water. Many dissolved minerals are not removed by activated carbon.  In the case of calcium, magnesium, potassium, and other beneficial minerals, the taste of the water can be improved and some (usually small) nutrient value can be gained from the water. The bottom line is that GAC filters are effective and valuable water treatment devices, but their limitations always need to be considered.  A uniform flow rate, not to exceed the manufacture's specifications, must be maintained for optimal performance, and the filter cartridge must be changed after treating the number of gallons the filter is rated for.   The disadvantages of GAC filters include: Water flowing through the filter is able to "channel" around the carbon granules and avoid filtration.  Water seeks the path of least resistance.  When it flows through a bed of loose carbon granules, it can carve a channel where it can flow freely with little resistance.  Water flowing through the channel does not come in contact with the filtration medium.  The water continues to flow, however, so you do not realize that your filter has failed - you get water, but it is not completely filtered. Pockets of contaminated water can form in a loose bed of carbon granules.  With changes in water pressure and flow rates, these pockets can collapse, "dumping" the contaminated water through the filter into the "filtered" flow. Since the carbon granules are fairly large (0.1mm to 1mm in  one popular pitcher filter), the effective pore size of the filter is relatively large (20 - 30 microns or larger).  GAC filters, by themselves, cannot significantly reduce bacterial contamination.   As described above, hot water should NEVER be run through a carbon filter Also, if you think of a bed of charcoal that traps an occasional bacterium, picks up a bit of organic material, and removes the chlorine from the water, you can see how these filters might become breeding grounds for the bacteria they trap. You will see warnings about GAC filters suggesting you run water through them for a few minutes each morning to flush out any bacteria. If you are considering purchasing a  GAC filter be sure to ask the representative about what they recommend you do about this potential problem (I was told by one sales person, that if the filter was not going to be used for a few days, I should remove the filtration element, place it in a plastic bag, and store it in the refrigerator until I returned). Unless the filter plugs up or you notice an odor in the "filtered water", it may be difficult to know when the filter has become saturated with contaminants and ineffective.  That is why it is necessary to change filter cartridges according to the manufacturer's recommendation. Solid Block Activated Carbon (SBAC): Activated carbon is the primary raw material in solid carbon block filters; but instead of carbon granules comprising the filtration medium, the carbon has been specially treated, compressed, and bonded to form a uniform matrix.  The effective pore size can be very small (0.5 - 1 micron).  SBAC, like all filter cartridges, eventually become plugged or  saturated by contaminants and must be changed according to manufacturer's specifications.  Depending on the manufacturer, the filters can be designed to better reduce specific contaminants like arsenic,  MTBE, etc. (an example)   The advantages of SBAC filters include: Provide a larger surface area for adsorption to take place than Granular Activated Carbon (GAC) filters for better contaminant reduction.  Provide a longer contact time with the activated carbon for more complete contaminant reduction. Provide a small pore size to physically trap particulates. If the pore size is small enough, around 0.5 micron or smaller, bacteria that become trapped in the pores do not have enough room to multiply, eliminating a  problem common to GAC filters. Completely eliminate the channeling and dumping problems associated with GAC filters. SBAC filters are useful in emergency situations where water pressure and electricity might be lost.  They do not require electricity to be completely effective, and water can even be siphoned through them. SBAC filters do not waste water like reverse osmosis. Many dissolved minerals are not removed by activated carbon.  In the case of calcium, magnesium, potassium, and other beneficial minerals, the taste of the water can be improved, and some (usually small) nutrient  value can be gained from the water. Simple, economical maintenance.  Typically an inexpensive  filter cartridge needs to be changed every few months to a  year, depending on water use and the manufacturer's recommendation. This combination of features provides the potential for greater adsorption of many different chemicals (pesticides, herbicides, chlorine, chlorine byproducts, etc.) and greater particulate filtration of parasitic cysts, asbestos, etc. than many other purification process available. By using other specialized materials along with specially prepared activated carbon, customized SBAC filters can be produced for specific applications or to achieve greater capacity  ratings for certain contaminants like lead, mercury, arsenic, etc.   The disadvantages of SBAC filters include:  SBAC filters, like all activated carbon filters, do not naturally reduce the levels of soluble salts (including nitrates), fluoride, and some other potentially harmful minerals like arsenic (unless specially designed) and cadmium.  If these contaminants are present in your water, reverse osmosis would usually be the most economical alternative followed by distillation. As described above, hot water should NEVER be run through a carbon filter As SBAC filters remove contaminants from the water they gradually  lose effectiveness until they are no longer able to adsorb the contaminants.  There is no easy way to determine when a filter is nearing the end of its effective life except that the 'filtered' water eventually begins to taste and smell like the unfiltered water.  The manufacturer's guidelines for changing filter cartridges should always be followed.   To ensure that marketing claims are accurate, check  NSF International to see if the SBAC filtration system you are interested in purchasing is certified to significantly reduce the contaminants you are concerned about. An example of a certified list of contaminants significantly reduced by a high-end SBAC filtration system (** at 200 percent of capacity - that's after filtering twice the rated volume of the filter**):  For Standard 042 - aesthetic    Chlorine Reduction, Class I     (actual chlorine reduction 99.9%)    Particulate Reduction, Class I     (actual particulate reduction down to 0.5 micron)    Chloramine Reduction     (actual chloramine reduction greater than 96%)    Taste and Odor Reduction  For Standard 053 - contaminants of health concern and measured percent reduction    Asbestos Reduction >99%    Chlordane Reduction >99.8%    Cyst Reduction 99.9%    Lead Reduction >98%    Mercury Reduction >99.3% (pH 8.5) >91.4 (pH 6.5)    MTBE Reduction 96.6%    PCB Reduction >98%    Toxaphene Reduction >93%    TTHM Reduction (Trihalomethanes) >99.8%    Turbidity Reduction >99%    VOC Reduction (volatile organic chemical) Reduction - you will see a    long list of specific VOCs (individual percent reduction for the various    VOCs can be found on the product certification sheet below, but    most are 98-99% or more). A few SBAC filtration systems have been certified for arsenic reduction:  What about the inexpensive GAC pitcher filters and faucet mount filters?  How effective are they for your water purification needs?. The answer to that question depends on what your water treatment goals are and the amount of filtered water you plan to use. The most popular brands are GAC filters that will sometimes also contain granules of an ion exchange medium (you can see and hear the granules rattling around).    They do reduce the level of some contaminants of health concern and thus are better than nothing. They are very limited in the type and number of contaminants they remove, typically chlorine and perhaps lead, copper, and/or cysts are reduced.  At about $5 - $10 for a filter cartridge capable of treating about 35 - 40 gallons, your filtered water will cost about $0.14 - $0.25 per gallon ( $58 - $90 per year if you use 35 gallons per month).  If you are using (or would like to use) much more than a gallon per day, and/or would like to remove more than a minimum number of contaminants, you should probably examine other options.  Since they contain a very small amount of very loose GAC granules, they CAN NOT be considered effective treatments for most biological contaminants or chemical contaminants of health concern.  The pitcher filters which contain a microfilter are typically certified to reduce cysts.  All of these filters are mostly designed to improve the aesthetics of drinking water (taste & odor improvement) and reduce levels of a limited number of harmful contaminants.  They are subject to possible bacterial growth channeling, and all the other problems of larger GAC filters.   How about effectiveness of the Solid Carbon Block faucet mount filters? The solid carbon block faucet mount filters are more effective than GAC filters in reducing contaminants. These filters, by nature, are quite small, though, and because filter effectiveness is dependent on contact time of the water with the filter media, a larger, high-quality solid carbon block filter will be more effective at reducing contaminants at the ame flow rate.  The difference is size can be striking - 4 ounces of activated carbon for a faucet mount filter vs. 32 ounces for a high-end filter, over 7 times more filter media.  Like the pitcher filters, the replacement cartridges for faucet mount filters tend to be relatively more expensive (typically $0.14 - $0.25 per gallon) compared to a high-quality solid block activated carbon replacement filter which will filter water for about $0.08 per gallon.  Using 2 gallons of filtered water per day would cost between $100 and $180 a year to replace 4 - 5 ounce faucet mount cartridges and about $60 to replace a 32 ounce high-end filter solid block activated carbon filter.

Bottled Water: Did the water in the bottle you just purchased really come from the beautiful spring shown on the label? How can you be sure the water in the bottle is any cleaner or safer than your tap water? How does the cost, both short term and long term, compare with other water purification options?  Bottled water is simply water from some source that a company (or in the case of water vending machines, the consumer) has placed in a bottle for resale.  Bottled water can have minimal (or no) processing - as in natural spring or mineral water, or it can be completely filtered and demineralized to nearly pure water and then have minerals added back to improve the taste. But, how can you be sure the water in the bottle you purchased is any cleaner or safer than your tap water?  Just like any of the other water treatment solutions, you will find reputable companies that provide a safe, quality product, and you will find companies that fill their bottles using the local, municipal water with marginal treatment.  There are 2 regulatory organizations, 1 trade association, and 1 independent certification organization, which contribute to ensuring the safety and quality of bottled water.  (A NRDC Discussion of Bottled Water) Bottled Water: Issues and Alternatives   According to the University of Illinois at Urbana-Champaign, College of Agriculture, Cooperative Extension Service, bottled water is regulated at the federal level, and in some cases, at the state level. Bottled water suppliers who are members of the International Bottled Water Association (IBWA) regulate themselves and are given unannounced inspections by NSF International.  Bottled water companies can also have their product certified by NSF International. Federal standards - Bottled water is regulated by the Food and Drug Administration (FDA), which requires manufacturers to submit samples regularly for testing. In the United States, the concentration of contaminants found in bottled water must be less than the "allowable levels" set by the FDA which are essentially the same as the maximum contaminant levels that the EPA requires municipal water supplies to meet. State standards - Individual states must enforce the federal bottled water regulations, but they can also pass stricter standards. International Bottled Water Association. The bottled water industry regulates itself through the International Bottled Water Association (IBWA). Bottled water FAQs. The IBWA sets manufacturing requirements, which help to ensure that bottlers meet FDA health standards. Bottled water producers who are members of IBWA are inspected annually by an independent laboratory, the National Sanitation Foundation. Through unannounced inspections, members are evaluated on compliance with the IBWA's performance requirements and FDA Quality Standards. Not all bottled water manufacturers are members of the IBWA. Of the 475 bottling plants in the United States (in 1994), 250 are members. The label may indicate whether a bottled water comes from a member company. You might want to check  NSF International to see if the bottled water you are interested in purchasing is certified.  The NSF Bottled Water Certification Program is an annual, voluntary certification process that includes both extensive product evaluations as well as on-site audits of bottling facilities.  The NSF testing program provides for annual unannounced plant inspections covering every aspect of a bottler's operation, from the source of the water, through the disinfection and treatment process, and including the container closure process. The company also performs extensive product testing for over 160 chemical, inorganic, radiological, and microbiological contaminants.  An interesting article from Scientific American magazine on bottled water. Advantages of Bottled Water include: An emergency source of water in the event your primary water source fails or becomes contaminated. A convenient source of usually safe water for drinking outside of the home. Bottled water, since it does not contain chlorine, and may contain a mix of minerals to enhance flavor, may taste better than untreated tap water. Most bottled water will contain fewer contaminants than untreated tap water. The bottled water industry would like the public to believe that bottled water is more pure and safer than tap water and water produced by other treatment methods.  The actual quality of bottled water depends on the bottling company, and most is usually good.  High quality home water treatment methods (filtration, reverse osmosis, and distillation) can usually produce water of equal or better quality more economically, however. The disadvantages of Bottled Water include: Cost Bulk Bottled: Bottled water costs anywhere from $0.25 a gallon for water from a vending machine machine to $0.50 for generic water jugs you purchase in a store to $1.00 - $1.50or more for water delivered to your home.  If you purchase 10 gallons of bottled water a week, you will spend $260 (at$.50/gal), $520 (at $1.00/gal), $780 (at $1.50/gal), or more every year.  Individual Bottles: Many people are willing to pay extraordinary prices for the availability and convenience of of certain products. That 16 ounce bottle of "designer water" you just purchased at the gas station for $0.69 costs $5.52 per gallon, probably more than twice as much per gallon as your gas! Purchasing just one 16 oz bottle per day (at $0.69 per bottle) will cost you over $250 per year - that's for a total of 45 gallons. If you were to take a minute to fill your own well-cleaned bottle with filtered or distilled water, however,  a 16 oz bottle of water would cost perhaps1 - 2 cents a day, or less than $7.30 per year! Inconvenience - Using bottled water requires moving and storing jugs or bottles of  water. Water weighs about eight pounds per gallon, or about 40 pounds per five gallon bottle.  Failure of a small valve can lead to a big mess, as I discovered after  arriving home one evening after a long day at work to find 3 gallons of water soaking into the rug. Negative Environmental Impact - Producing bottles uses resources, and unless they are  reused or recycled, they cause a waste disposal problem.  Recycle or reuse the empty bottles, if at all possible.  Transporting bottles of water from the bottler to stores or homes also uses resources. Keep Your Bottle Clean - According to the University of Illinois at Urbana-Champaign, College of Agriculture, Cooperative Extension Service, "If you choose bottled water after careful investigation, keep in mind that all of your hard work will go to waste if you aren't careful about keeping your bottled water clean. You have to be faithful in maintaining the hygiene of your bottled water, or you may increase your exposure to bacteria. Bacteria grow best in warm, moist areas. The wet, warm, threaded cap of an unrefrigerated bottle of water is a perfect place for bacteria to grow; they will begin to grow as soon as you break the seal. If ingested, these bacteria can cause gastrointestinal problems and other health risks. The key is to maintain the cleanliness of your bottles and store them properly. Follow these hints:  1) Store opened bottles in a refrigerator at a temperature above freezing but less than 50 degrees Fahrenheit. 2) Wipe the seal with a clean cloth after each use. 3) Avoid any type of buildup in the bottle cap.  4) If your bottle is refillable, make sure it is well-cleaned and rinsed before refilling. If possible, recycle the old bottle and obtain a fresh, sterile, sealed bottle." 5 gallon water dispensers must also be kept meticulously clean to prevent bacteria from growing in the reservoir area and bubbling into the bottle.  Safety & Health Services cleaning recommendations. (pdf file)

Ultra Violet Light: Water passes through a clear chamber where it is exposed to Ultra Violet (UV) Light.  UV light effectively destroys bacteria and viruses.  However, how well the UV system works depends on the energy dose that the organism absorbs.  If the energy dose is not high enough, the organism’s genetic material may only be damaged rather than disrupted.   The advantages of using UV include: No known toxic or significant nontoxic byproducts introduced. Removes some organic contaminants, although specifics are difficult to locate. Leaves no smell or taste in the treated water. Requires very little contact time (seconds versus minutes for chemical disinfection). Improves the taste of water because some organic contaminants and nuisance microorganisms are destroyed. Many pathogenic microorganisms are killed or rendered inactive. Does not affect minerals in water. The disadvantages of using UV include: UV radiation is not suitable for water with high levels of suspended solids, turbidity, color, or soluble organic matter.  These materials can react with UV radiation, and reduce disinfection performance. Turbidity makes it difficult for radiation to  penetrate water and pathogens can be 'shadowed', protecting them from the light.  UV light is not effective against any non-living contaminant, lead, asbestos, many organic chemicals, chlorine, etc.   Tough cryptosporidia cysts are fairly resistant to UV light.  Like Ozone, UV light can degrade some organic compounds into equally harmful byproducts. Requires electricity to operate.  In an emergency situation, when the power is out, the purification will not work. UV is typically used as a final purification stage on some filtration systems.  If you are concerned about removing contaminants in addition to bacteria and viruses, you would still need to use a quality carbon filter or reverse osmosis system in addition to the UV system.

 

Water Softeners and deionizers: Water softeners operate on the ion exchange process (specifically a cation exchange process where + ions are exchanged).  In this process, water passes through a media bed, usually sulfonated polystyrene beads. The beads are supersaturated with sodium (a positive ion). The ion exchange process takes place as hard water passes through the softening material. The hardness minerals (positively charged Calcium and Magnesium ions) attach themselves to the resin beads while sodium on the resin beads is released simultaneously into the water.  When the resin becomes saturated with calcium and magnesium, it must be recharged. The recharging is done by passing a concentrated salt (brine) solution through the resin. The concentrated sodium replaces the trapped calcium and magnesium ions which are discharged in the waste water. Softened water is not recommended for watering plants, lawns, and gardens due to its elevated sodium content. Several factors govern the efficiency of a cationic softener:   Type & quality of resin used;   Amount of salt per cubic foot of resin for regeneration;   Brine concentration in the resin bed during regeneration;   Brine flow rate through the resin bed (contact time) during regeneration;   Raw water hardness;    Raw water temperature - softeners perform better at higher temperatures; and   Optimal flow rate of hard water through the resin bed. Although not as commonly used, potassium chloride can be used to create the salt brine for softeners designed to use KCl. In that case potassium rather than sodium is exchanged with calcium and magnesium. Before selecting an ion exchange water softener, test water for hardness and iron content. When selecting a water softener, the regeneration control system, the hardness removal capacity, and the iron limitations are three important elements to consider.  More information on Hard Water and Softening. The advantages of water softeners include: The nuisance factor of hard water is reduced. Some other other cations like barium, radium and iron may be reduced depending on the manufacturer's specifications. The disadvantages of water softeners include: The process of regenerating the ion exchange bed dumps salt water into the     environment. The elevated sodium concentration of most softened water can affect the taste     and may not be good for people on low sodium diets, although sodium     concentrations are typically quite low relative to sodium levels in most food. Cation exchange does not reduce the level of anions (like nitrates), or biological     contaminants (bacteria, viruses, cysts) ; nor does the process reduce the levels of     most organic compounds. Typically, approximately 50 gallons of rinse water per cubic foot of resin is     required to totally remove hardness and excess salt from the resin after each     regeneration. This page describes Traditional Water Softeners and Non-salt Water Conditioners Water Deionizers use both Cation and Anion Exchange to exchange both positive and negative ions with H+ or OH- ions respectively, leading to completely demineralized water.  Deionizers do not remove uncharged compounds from water, and are often used in the final purification stages of producing completely pure water for medical, research, and industrial needs. A potential problem with deionizers is that colonies of microorganisms can become established and proliferate on the nutrient-rich surfaces of the resin. When not regularly sanitized or regenerated, ion-exchange resins can contaminate drinking water with bacteria.

 

KDF "Filters": KDF filters employ a matrix (generally small granules) of a zinc/copper alloy, which are claimed to eliminate contaminants from water by utilizing electrochemical oxidation reduction. Claims include the ability KDF to: Remove chlorine (actually changes free chlorine to a less active form). Kill algae and fungi. Control bacterial growth in the filter. Remove hydrogen sulfide, iron, lead, cadmium, aluminum, mercury, arsenic and other inorganic compounds. Partially reduce hardness. Remove hydrogen sulfide, iron, lead, cadmium, aluminum, mercury, arsenic and other inorganic compounds. Zinc and copper are the preferred metals used in the KDF alloy since both are relatively good reducing agents with respect to common inorganic contaminants (such as chlorine), and both can be tolerated in solution in moderate concentrations without adverse side effects. The advantages of KDF filters include: KDF is the only filter medium I am aware of that claims to remove contaminants from running hot water (unlike carbon filters where hot water can release trapped contaminants into the water stream).  This makes them ideal for use in the shower.  The filters change the free chlorine some people are allergic to into a form (zinc chloride) that is much more easily tolerated. The disadvantages of KDF filters include: KDF filters do not, by themselves, remove organic chemicals (pesticides, disinfection byproducts, MTBE, etc.), or parasitic cysts (giardia and cryptosporidium).  If you are concerned about removing any of these contaminants, other strategies will be needed in addition to the KDF media. KDF filters need to be backwashed periodically with hot water to remove the insoluble contaminants.  This method wastes many gallons of hot water and there is no way to prevent dislodged pollutants from coming out later with the supposedly filtered water. There is a web site from a chemist that casts doubt on some the contaminant reduction claims made for KDF (or at least on the chemical processes put forward to explain the reduction).  I have searched for independent confirmation of claims, and there is remarkably little available on the Internet for a product that is so widely used.

  

Ozonation:   The formation of oxygen into ozone occurs with the use of energy. This process is carried out by an electric discharge field as in the CD-type ozone generators (corona discharge simulation of the lightning), or by ultraviolet radiation as in UV-type ozone generators (simulation of the ultra-violet rays from the sun). In addition to these commercial methods, ozone may also be made through electrolytic and chemical reactions. Ozone is a naturally occurring component of fresh air. It can be produced by the ultraviolet rays of the sun reacting with the Earth's upper atmosphere (which creates a protective ozone layer), by lightning, or it can be created artificially with an ozone generator.  The ozone molecule contains three oxygen atoms whereas the normal oxygen molecule contains only two.  Ozone is a very reactive and unstable gas with a short half-life before it reverts back to oxygen. Ozone is the most powerful and rapid acting oxidizer man can produce, and will oxidize all bacteria, mold and yeast spores, organic material and viruses given sufficient exposure.   The advantages of using Ozone include: Ozone is primarily a disinfectant that effectively kills biological contaminants.  Ozone also oxidizes and precipitates iron, sulfur, and manganese so they can be filtered out of solution.   Ozone will oxidize and break down many organic chemicals including many that cause odor and taste problems. Ozonation produces no taste or odor in the water. Since ozone is made of oxygen and reverts to pure oxygen, it vanishes without trace once it has been used.  In the home, this does not matter much, but when water companies use ozone to disinfect the water there is no residual disinfectant, so chlorine or another disinfectant must be added to minimize microbial growth during storage and distribution. The disadvantages of using Ozone include: Ozone treatment can create undesirable byproducts that can be harmful to health if they are not controlled (e.g., formaldehyde and bromate).   The process of creating ozone in the home requires electricity.  In an emergency with  loss of power, this treatment will not work. Ozone is not effective at removing dissolved minerals and salts. Caution - The effectiveness of the process is dependent, on good mixing of ozone with the water, and ozone does not dissolve particularly well, so a well designed system that exposes all the water to the ozone is important. In the home, ozone is often combined with activated carbon filtration to achieve a more complete water treatment.

'Altered' Water: No discussion about water treatment would be complete these days without mention of what I call "altered" water - water that has been treated in some way to allegedly  modify the physical, chemical, or 'energy' properties of water to provide some benefit to the body.  These treatments fall under a wide range of categories, including: pi mag; oxygenation; hydrogenation; various 'catalytic', vortex, magnetic, & photonic treatments; microclustering; super-ionization; homeopathic succussions; etc. Note - Oxygenated water, discussed below, is just one example of the hundreds of 'altered' or 'enhanced' water products promoted on the internet and in some health food stores.  These products all have several characteristics in common that are discussed in more detail on the Altered Water and Drinking Water Scams pages.  It is easier to demonstrate the flaws in Oxygenated water claims than in other products that claim to use some exotic physical or chemical process, but just like oxygenated water, none of the other products are able to withstand critical scientific review. Regardless of any alleged  health benefits, these products are extremely effective at separating customers from their money - I have seen some of this bottled water sell for more than $20 a gallon plus shipping (that's over 3,000 times greater than the cost of tap water)!  Many of the 'altered' water products sell for $10 to $15 per gallon.  Water 'ionizers' that generate alkaline water produce sodium hydroxide (an effective drain cleaner) and bleach and sell for up to $5,000. Let's look briefly at one 'altered' water example: hiOsilver oxygenated water - soon to be O2Cool Oxygen Water: Why drink hiOsilver oxygen water? According to the marketing hype, it provides "extra energy and vitality, fresh breath, healthier gums and teeth. We do not know all of the benefits of drinking hiOsilver Oxygen Water.  Many people report that they feel energized after a bottle. Studies have been done showing enhanced sports performance for athletes drinking oxygenated water. With hiOsilver, many people report that their headaches disappear, even migraine headaches. One bottle of hiOsilver Oxygen Water and you will see why we are proud of the many benefits it offers over ordinary bottled waters . . . " hiOsilver oxygenated water water sells for $44 (for twenty four, 16 oz bottles - 3 gallons) but you do get free shipping! If my math is correct, that's over $14.50 per gallon.  By comparison, tap water costs around $0.007 per gallon (2,000 times less than the oxygenated water).  The highest quality filtered water is about $0.07 per gallon (that is still over 200 times less expensive than the oxygenated water).  I suppose some people might be able to justify the exorbitant cost IF the product performed as advertised --- but does it?  The super oxygenating water cooler system marketing materials make these 'exciting' claim - and a skeptical review - Extra supply of oxygen to the body for overall health improvement - Enhancement of the brain function for clearer thinking and alertness - More oxygen to the muscle to increase energy and performance - More oxygen to skin cells for healthier, younger looking skin - Enhanced metabolism and waste removal - Enhancement of the body's ability to fight bacteria and viruses - Better absorption of vitamins, minerals and other nutrients (A 2011 update - the Oxygenating Cooler is apparently no longer on the market) Some facts to consider when evaluating the oxygenated water hype: There is less dissolved oxygen in 1 liter of 'oxygenated water' than in 1 breath of air.  Taking an extra breath of air when exercising  would be substantially less expensive than paying $1 to $2 for a liter of these products! The primary way to transport oxygen in the body is bound to hemoglobin in the red blood cells.  In normal healthy exercisers, hemoglobin leaving the lungs is already 97% to 98% saturated with oxygen. The structure of the circulatory system ensures that any oxygen picked up in the digestive system would o through the lungs before reaching the muscles and other tissues.  In the lungs any extra oxygen in the blood will reduce the amount of oxygen transferred to the blood - the final oxygen saturation of the hemoglobin would still be 97% to 98%. Oxygenating water has no effect on the body's ability to absorb the oxygen into the bloodstream or  transfer it throughout the body.. The concept of obtaining significant amounts of oxygen through the digestive system makes as much scientific and physiological sense as quenching your thirst by inhaling a glass of water into your lungs.  Water that you drink can take up to an hour or more to travel to the intestines where it is absorbed - the water you inhale into your lungs will absorb into your bloodstream almost immediately - so doesn't it make sense to quench your thirst by inhaling a glass of water?   (Do not try this experiment!!) This is not an endorsement for inhaling water.  The point is, the respiratory system is designed to absorb oxygen, no water!  Oxygenated water makes sense for fish  that have specialized structures (gills) for exchanging oxygen and carbon dioxide in an aquatic environment, but not for mammals.  Similarly, the digestive system is designed to absorb water and nutrients, not oxygen! American Council on Exercise (ACE) Study Investigates Super Oxygenated Water Claims - Results of a study done to test health claims.  Conclusion: “At this time, there is no scientific evidence or logical rationale to suggest that drinking super oxygenated water can in any way increase the amount of oxygen in the blood stream,” said Porcari. “Therefore, any potential benefits of super oxygenated water would undoubtedly be attributed to the placebo effect.” A single breath of air contains more oxygen than a bottle of oxygenated water. Despite advertising claims that oxygenated water can boost sports performance, a study in the Nov. 12, 2003, Journal of the American Medical Association found that compared with tap water, it had no effect on 9 exercise-performance measures in 11 healthy men and women.  Ben Goldacre of The Guardian reviews Oxygizer Oxygenated water bottled in Austria.  Oxygen water: Are you being ripped off?  There's very little reliable evidence to show that oxygenated (or oxygenized) water has any significant effect on exercise performance, energy levels, or recovery. This water isn't going to hurt you, but there's no reason to believe it's going to help you substantially. Oxygenated Water from Kevin Sayers' UltRunR site Another reason Oxygenated water was selected as an example is because there are actually some well-conducted experiments available that demonstrate that the product does not perform as advertised.  With most of the 'altered' water products, scientists do not bother spending the time or resources to refute claims which they perceive as completely and obviously bogus and not worth examining. Be aware of the following when evaluating these products: None of these products is effectively regulated by the government (over and above standard rules to ensure safety of bottled water - discussed under the Bottled Water section above).  Companies seem completely free to make any unsubstantiated claims they wish (except specific health claims - which would place them under the jurisdiction of the FDA where they would be required to scientifically prove their claims). With that in mind, read the promotions very, very carefully.  You will find that the companies describe various health conditions in great detail.  Then they attribute the condition (sometimes accurately) to a lack of water, or polluted water, or insufficient oxygen, etc.  However,  they seldom link their specific process of treating the water directly to solving the specific health problem they discussed - except in the most general, unverifiable way, like 'drinking enough water is critical to your health', or 'drinking our water will reduce stress and give you more energy'.  Any claims on the site that directly link the specific water treatment to specific health benefits are typically made by 'others' in testimonial statements.  There are no regulations in place to ensure that testimonials are either truthful or accurate or even come from real individuals. There will be much mention in the promotional materials about scientific tests proving that a particular water treatment has some benefit to the body, to endurance, to mental function, or whatever.  There will be, however, a complete lack of substantiated scientific evidence to back up those claims.  Acceptable evidence would be experimental results published in  journal articles that have been reviewed by other scientists to make certain the experiments were carried out (and interpreted) correctly and with minimal bias. Aqua Scams - The purpose of this site is to examine the scientific validity of the explanations given by the proponents of "alternative" water treatment devices or, in the case of "clustered water", of a fictional alternative form of water that is purported to be a restorer of youth and vigor. My motivation for doing this is entirely non-vested and very simple: after thirty-four years of teaching general, physical, and environmental Chemistry, it disturbs me to see my favorite science presented incorrectly (and often mangled into pseudoscience) in the promotion of processes or devices offered to the public (Stephen K. Lower, Ph. D., site author).  Two other relevant topics Dr. Lower discusses: Cluster Quackery, Structure-altered water nostrums and nonsense and Oxygenated water, pseudoscientific snake-oil.  A site from the James Randi Educational Foundation has several interesting comments on Penta Water and the Foundation's attempts to persuade the company to participate in their million dollar challenge. http://www.randi.org/jr/08-24-01.html, http://www.randi.org/jr/08-31-01.html, http://www.randi.org/jr/110201.html (about 3/4 of the way down), http://www.randi.org/jr/083002.html (about 1/2 of the way down) and http://www.randi.org/jr/121903lins.html ( just over 1/2 of the way down) Index of Water-Related Frauds and Quackery My response to questions asked by one of my visitors about claims made by companies selling "altered water" and how to evaluate them.   In the final analysis,  I would have to say that I have seen absolutely nothing that would lead me to believe that any of these specialized water treatment methods can do anything at all to increase the health benefits of water that is free of harmful contaminants. I would be extremely interested to see some results of good scientific experiments that demonstrated any beneficial health effects of drinking "altered" water.  My belief is that good scientific studies on this topic simply do not exist, because the claims can not be verified.  You might ask why don't  scientists carry out experiments and publish results refuting these claims if they are not true.  My best guess is that for the scientific community these are non-issues.  There are far more interesting and important topics to spend valuable research resources and effort on than debunking strange theories and marketing tactics that result in people eagerly spending their money on outrageously priced water products.  I often receive questions about Masaru Emoto's books and theories that water is able to receive human thoughts, words, and emotions and change the way it crystallizes - forming beautiful crystals in response to positive thoughts, words, and emotions and ugly crystals (or no crystals) in response to negative thoughts, words, and emotions (or pollution).  There is absolutely no scientific evidence to support his claims.  I discuss my thoughts on his popularity (among non-scientists) here.

Comparison of Drinking Water Treatment Methods I developed a Comparison Table listing different drinking water treatment technologies and the contaminants they remove to make it easier for you to determine which process, or combination of processes will be best for your particular drinking water situation.   If this table is too large for your screen, I have     broken it into two separate tables, one     covering the biological and organic     contaminants, and the other covering the     inorganic contaminants.  They should be     easier to read on monitors set at 800 X 600. I also developed another table that shows similar water treatment information in a somewhat different format that you might want to take a look at.  This table is geared mostly to point of use water treatment methods. The Water Quality Association (WQA) also has a Table of Water Contaminants, their health effects, and removal methods

Relative Size Click here to view a full sized figure that compares the relative size of several biological contaminants with the pore size of some common filters.

Comparison of Long-Term Costs for Water Treatment Have you considered how much it will cost to obtain pure, safe water for the next 5, 10, 20, or even 40 years? When you decide to protect yourself and your family from drinking water contaminants, 40 years may seem like a very long time to think about treatment costs..... However - If you plan to use just 10 gallons of purified water a week (less than 1.5 gallons per day), the water treatment method you select can mean the difference between spending about $1,500 over 40 years or spending more than $31,000 for pure, safe water! Click below on the amount of purified water you use (or would like to use) per week.  This will display a table and graph comparing the average costs of some common treatment methods (bottled water, distillation, reverse osmosis, SBAC filtration, and pitcher filters). 5 gallons per week 10 gallons per week 15 gallons per week 20 gallons per week 25 gallons per week These cost tables (as well as the filter performance tables) convinced me to consider seriously a top-of-the line, Solid Block, Activated Carbon (SBAC) filtration system.  Although the initial cost was higher than many cheaper alternatives, the cost over several years was much lower than other options - at most usage levels.  The fact that SBAC filtration was simpler to use than other methods and significantly reduced all contaminants I was liable to experience in my municipal water, sold me on the technology.  I have provided some information on how to request information about my recommendation for a top-of-the-line SBAC filtration system.