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Comparison of Treatments and Options for Drinking Water
Drinking water (also known as "potable water") is defined as water which is fit for consumption by humans and other animals. Water may be naturally potable, as is the case with pristine springs, or it may need to be treated in order to make it safe to drink.
Two important terms related to water treatment:
- Water Purification - a process which removes specified contaminants from a water source.
- Water Disinfection - a purification process that kills or removes biological contaminants such as cysts, bacteria, viruses, protozoans, etc. from a water source.
- Water that has been disinfected may still be polluted with contaminants that are not affected by the disinfection treatment.
- In some cases, additional contaminants may actually be added to the water during the disinfection process.
- For instance, the process of chlorination nearly always adds some disinfection byproducts.
- boiling water will actually concentrate inorganic contaminants.
Local water companies are supposed to provide biologically and chemically safe water that has most objectionable taste and odor causing substances removed. As you have read and heard in the news, this is unfortunately not always the case.
Public water purification in this country relies heavily on chemical disinfection. The most commonly used chemical is chlorine. We have to be thankful for what chlorine does. It has prevented the cholera and typhoid outbreaks that can decimate entire populations. But, we also need to be aware of its drawbacks. Not all bacteria can be removed through chemical disinfection. If you drink municipal "tap water", you run the risk of contracting illnesses ranging from diarrhea to serious gastrointestinal complications.
Cryptosporidium is one type of bacteria that is resistant to chlorine disinfection. Government agencies say that no matter how good your public water purification system is, there is a risk of cryptosporidium contamination. They also say that it is difficult to test for. People who become infected by the parasite have, in some cases, died from the infection.
The chemicals used at public water purification facilities are health hazards to humans, as well as the germs they target. They cause skin irritation, digestive problems and have been linked to various forms of cancer. Another problem that public water purification plants cannot address are the by-products of disinfection.
One of these by-products, known as THMs, is chloroform gas. Government agencies have said that chloroform gas is present in most homes around the country. The gas is a health hazard that causes dizziness and headaches, but worse yet, the THMs build up in the fat cells of your body.
In women with breast cancer, it has been found that the THMs in their fatty tissue are nearly twice as high as that found in healthy women. This finding seems to indicate a link between THMs and cancer.
As municipal water is distributed through your home via plumbing, there is a risk of contamination from lead leaching into the water supply from pipes and/or fixtures.
In summary, the contaminants most people using public water may experience at harmful or unacceptable levels are:
- Residual disinfectants, like chlorine and/or chloramine
- Disinfection byproducts, like the trihalomethanes
- Microbes like E. coli, giardia, cryptosporidia, etc. or other contaminants
- Nitrates or organic compounds (f you live in an agricultural region)
Which Drinking Water Option is Best ?
With such a risk drinking municipal water . . . most people want a safer alternative . . . but with so many options . . . how does one know which is best for them ? We will try to shed some light on this very serious and confusing issue.
We will be reviewing the following treatments and options:
Atmospheric Water Generation (AWG)
- Bottled Water
Question: Did the water in the bottle you just purchased really come from the beautiful spring shown on the label ?
Answer: Probably not
Question: Is bottled water any cleaner or safer than your tap water ?
Answer: The actual quality of bottled water depends on the bottling company . . . some is good, but some is not.
Question: How does the cost and quality of bottled compare with other water purification options ?
Answer: High quality home water treatment methods can usually produce water of equal or better quality more economically.
- There has been an explosion in bottled water use in the United States, driven in large measure by marketing designed to convince the public of bottled water's purity and safety, and capitalizing on public concern about tap water quality. People spend from 240 to over 10,000 times more per gallon for bottled water than they typically do for tap water.
- Some of this marketing is misleading, implying the water comes from pristine sources when it does not. For example, one brand of "spring water" whose label pictured a beautiful lake and mountains, actually came from a well in an industrial facility's parking lot, near a hazardous waste dump, and periodically was contaminated with industrial chemicals at levels above FDA standards.
- According to government and industry estimates, about one fourth of bottled water is bottled tap water (and by some accounts, as much as 40 percent is derived from tap water) -- sometimes with additional treatment, sometimes not.
The advantages of Bottled Water:
- 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.
- Since it does not contain chlorine, and may contain a mix of minerals to enhance flavor, bottled water may taste better than tap water
- Most bottled water will contain fewer contaminants than untreated tap water.
The disadvantages of Bottled Water:
- Cost -
- Bottled water costs anywhere from $0.25 a gallon for water from a vending machine
- to $0.50 for generic water jugs you purchase in a store
- to $1.00 - $1.50 or more for water delivered to your home.
- If you purchase 10 gallons of bottled water a week, you will spend
$260 (@ $.50/gal), $520 (@ $1.00/gal), $780 (@ $1.50/gal), or more every year.
- Many of us are willing to pay extraordinary prices for the availability and convenience 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 close to the cost per gallon of your gas!
- Purchasing one16 oz bottle per day (@ $0.69 per bottle) will cost you $248 per year - that's for a total of 45 gallons.
- 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.
- Potential Health Risk of Plastic Bottles - Some researchers are worried that plastic bottles which contain the chemical BPA may be harmful to our health. While the Food and Drug Administration and the American Plastics Council insist BPA is safe, Frederick Vom Saal, an outspoken biology professor and other scientists believe it may bring all kinds of harm -- such as cancer, early puberty, obesity and even attention-deficit disorder. Vom Saal stumbled onto BPA in 1997 while studying fetal development. He found that BPA passed through the protective placenta from mother to baby, mimicking the behavior of the natural hormone estrogen. Having studied BPA ever since, Vom Saal, said there is so much BPA in the environment it is as if we are all wearing "a sex hormone patch."
- 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.
- Keep it Clean - According to the University of Illinois at Urbana-Champaign,College of Agriculture, Cooperative Extension Service,
"If, after careful investigation, you choose bottled water, 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
- Store the bottle in a refrigerator at a temperature above freezing but less than 50 degrees Fahrenheit
- Wipe the seal with a clean cloth after each use.
- Avoid any type of buildup in the bottle cap.
- 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.
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. They work by physically preventing contaminants from moving through the filter. There are 4 main types of filters:
- Sediment Filters - trap contaminants by screening them out with very small pores.
- Carbon Filters - trap contaminants by attracting them (through the process of adsorption) to the surface of carbon particles.
- Reverse Osmosis Filters - use water pressure to force water molecules through a membrane that has extremely tiny pores, leaving the larger contaminants behind.
- KDF Filters - use electrochemical oxidation and reduction to eliminate contaminants from water.
Filter performance is often rated in terms of 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 most filtration methods. In theory, reverse osmosis will remove viruses, however, just a small flaw in the membranes would allow viruses to pass undetected into the 'filtered' water. UltraFiltraton (UF) membranes used in Xzenix Atmospheric Water Generators are the only filter systems that can reliably remove viruses.
A benefit of most home filtration systems is that they are passive. That is, they require no electricity to filter the water. The only routine maintenance required is periodic replacement of the filtration element.
These filters strain solid particles out of the Water and come in 2 varieties - Fiber and Ceramic:
Fiber filters contain cellulose, rayon or some other fibrous material spun into a mesh with small pores, while ceramic filters contain some ceramic media with typically smaller pores than fiber filters. If you take some water containing sand and pour it through a piece of cloth you will get the picture. Suspended sediment (or turbidity) is removed as water pressure forces water through tightly wrapped fibers or ceramic media. These filters provide mechanical filtration only and are often used as pre-filters to reduce the suspended contaminants that could clog carbon or RO filters.
Sediment filters can reduce asbestos fibers, cysts and some organic particles that cause disagreeable odors and taste, but will not remove viruses or contaminants that are dissolved in the water, like chlorine, lead, mercury, trihalomethanes or other organic compounds.
||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.
There 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
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.
The adsorption process depends on the following 5 factors:
- physical properties of the AC, such as pore size distribution and surface area
- the chemical nature of the carbon source
(the amount of oxygen and hydrogen associated with it)
- chemical composition and concentration of the contaminant
- the temperature and pH of the water
- the flow rate or time exposure of water to AC
Activated carbon filter cartridges will, become less effective over time, as the pores clog with particles (slowing the 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.
It is also 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, as this will result in the release of 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 advantages of GAC filters:
- 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, which makes them suitable 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, needs to 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:
- 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 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, can not trap bacteria.
- As described above, hot water should NEVER be run through a carbon filter.
- Granular Activated Charcoal (GAC) filters have relatively large, and irregular sized pores (10 microns would probably be the minimum size to expect), so it is impossible to state with any certainty what size particles would be removed. Channeling can also dump unfiltered water into the output stream. GAC only filters should never be relied on exclusively to provide protection from small particulate contaminants.
- 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.
- 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 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.
The advantages of SBAC filters:
- Provide a larger surface area for adsorption to take place than 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.
- Solid Block, Activated Carbon filters have very small carbon particles bonded into a tightly packed matrix with uniform pores, typically between 0.5 and 1.0 micron, and can reliably remove small particulate contaminants.
- 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.
The disadvantages of SBAC filters:
- 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 and cadmium. If these contaminants are present in your water, SBAC filtration would not be a good option.
- 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. It is critical to follow the manufacturer's guidelines for changing filter cartridges.
Many people use the inexpensive GAC pitcher filters and SBAC faucet mount filters,
however, neither one really provides a good solution for most water purification needs . . .
Both will reduce the level of some contaminants . . . so they are better than nothing . . . But since both are very limited in the type and number of contaminants they remove, and are quite pricey (when you consider how often they need to be replaced)
. . . they really are not a very good, cost effective option. Furthermore, because they need to be replaced so often, most people neglect to replace them when they should, which results in "poor" quality drinking water . . . potentially worse than municipal tap water.
The problem with GAC pitcher filters is that they are quite small and 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 . . . typically just chlorine and perhaps lead, copper, and/or cysts . . . but are subject to possible bacterial growth channeling, and all the other problems of larger GAC 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 same 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.
Reverse Osmosis (RO):
Reverse Osmosis is a separation process which uses water pressure (in excess of the osmotic pressure) to force water molecules through a semipermeable membrane. 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. This is the reverse of the "normal" osmosis process, where water moves naturally . . . through a semipermeable membrane . . . from an area of low solute concentration . . . to an area of high solute concentration (with no external pressure applied).
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:
- 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 - so 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:
- Point of Use RO units make only a few gallons of treated water a day for drinking or cooking.
- 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 factors impact the RO membrane's efficiency in reducing the amount of contaminant in the water. These include the water's pH, temperature and pressure; the contaminant's concentration and checmical proprties as well as the membrane type and condition.
- Although RO filters do not use electricity, they depend on a relatively high water pressure to force the water molecules through the membrane. In an emergency situation where water pressure has been lost, these systems will not function.
- 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.
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.
KDF filters employ a matrix (generally small granules) of a zinc/copper alloy, which eliminates contaminants
from water by utilizing electrochemical oxidation reduction. The chemical properties of KDF (Kinetic Degradation Fluxion) include its ability 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
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:
- KDF is the only filter medium that removes 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 media (unlike activated carbon) is recyclable.
The disadvantages of KDF filters:
- 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.
In an emergency, boiling is the best way to purify water that is unsafe because of the presence of protozoan parasites or bacteria.
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:
- 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 purify drinking water except in emergencies.
The disadvantages of Boiling Water:
- 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
In many ways, distillation is the reverse of boiling. 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 the more complete removal of contaminants.
The advantages of Distillation:
- A good distillation unit produces very pure water. This is one of the few practical ways to remove 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.
- No drop in quality over time - As long as the distiller is kept clean and is working properly the high quality of treated water will be very consistent.
- No filter cartridges to replace, unless a carbon filter is used to remove volatile organic compounds.
The disadvantages of Distillation:
- Distillation takes time to purify the water, It can take two to five hours to make a gallon of distilled water.
- Distillers uses electricity all the time the unit is operating
- 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.
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:
- No known toxic or significant nontoxic byproducts introduced
- Removes some organic contaminants
- 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:
- 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.
- Requires electricity to operate. In an emergency situation when the power is out, it 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.
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:
- 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 a 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:
- Ozone treatment can create undesirable byproducts which may be harmful to health if they are not controlled (e.g., formaldehyde and bromate).
- Ozonation requires electricity to operate. In an emergency situation when the power is out, it 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.
Atmospheric Water Generators (AWG):
Fortunately, there is a new technology that offers a remarkable solution to the global water crisis. AWS has introduced DewPointe - - - an atmospheric water generator (AWG) which utilizes a revolutionary patented technology to convert ambient atmospheric water vapor into potable water. In other words The DewPointe produces pure drinking water . . . out of thin air. . . providing pristine, sparkling clear water in the purest form - much like crystal-like dew found only on the purest mountain tops.
The purification system on board the DewPointe, is a hybrid model - deploying several stages of the best purfication methods available . . . plus an advanced, proprietary ultrafiltration (UF) membrane. This patented UF technology with a pore size of .015 micron, removes virtually all bacteria and common viruses. the DewPointe is NSF 53 certified which means they have passed the highest drinking water treatment standard and will remove volatile organic chemicals. VOCs such as ether, have proven extremely difficult to remove by filtration methods of the past, but are not present in the water generated by the DewPointe water generation machine.
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How Atmospheric Water Generators work
- The DewPointe machine first pulls air through an electrostatic filter, removing 93% of all air born particles.
- A condensation unit receives this clean humid airflow and condenses water vapor into liquid.
- As the machine collects the water, it drops into a collection tray and immediately passes into Ultraviolet (UV) light, where the water stays in contact with UV rays for approximately 30 minutes. This kills over 90% of all germs and bacteria in the water.
- The water is then pumped through a sediment screen and then through 2 solid block activated carbon (SBAC) 1 micron filters, which removes over 90% of any volatile organic chemicals (VOCs) that may be in the water.
- The water is then filtered through AWS's proprietary ultrafiltration (UF) membrane, with a pore size of .015 micron, to remove virtually all bacteria and common viruses.
- The water is then pumped into a reservoir tank.
- From the reservoir tank, the water is recycled every 30 minutes through the UV and back into the reservoir tank.
- The water is then chilled or heated and dispensed at the consumer's convenience.
The AWS Technology:
This revolutionary technology is helping to meet the growing demand for economical, good tasting, quality drinking water.
Atmospheric water generation is a green friendly, alternative water source, for anyone who wishes to maintain control over their own pure water supply. The Dewpointe has been designed to perform at optimum levels, producing high quality water while consuming minimal electricity.
The Air2Water Technology Difference:
The following results are from water quality tests conducted on water sampled 05/01/05.
The advantages of Atmospheric Water Generators:
- Most effective purification system - its unique hybrid model utilizes the "best of all worlds"
removing everything . . . viruses, bacteria, VOCs, inoganic chemicals, dirt, pollution and residual chlorine.
- Cost effective - costs less than $.10 per gallon to operate
- it takes less than 18 months to recover the cost of purchase.
(based on cost savings . . . compared to that of a conventional 5 gallon water cooler)
- The cost effectiveness is dependent on humidity.
Click Here to see a how the 24 hour water production varies with humidity.
- Convenient - No bottles to carry and store.
- Green friendly
- Does not contribute to the plastic bottle landfill crisis.
- Does not waste water.
- Very efficient use of power.
- With less moisture in the air, your air-conditioning electrical consumption will be lowered . . .
as less energy is needed to cool the environment
- Can be run on solar power
The disadvantages of Atmospheric Water Generators:
- Does not provide a high yield of water in areas with low humidity . . .
but can be connected to a tap water supply for high quality, filtered water on demand
- Requires electricity to operate. In an emergency situation when the power is out, it will not work . . .
but can be powered by alternative energy like solar, wind or even gas or oil fired generators . . .
which can be of great help, especially when such machines are put into operation for relief efforts.
When you consider all of the options . . . It really is a "no-brainer" . . .
Atmospheric Water Generation . . . makes the most sense.
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