When we discuss "high purity" drinking water---we are specifically talking about water from which virtually all types of unwanted contamination have been removed. This includes organic chemicals(such as TCE, pesticides, and all other carbon-based materials), inorganic salts(such as sodium, metals, lime, nitrates), radioactive materials and biological growths such as bacteria.

Regardless what you might hear from fast-talking salespersons or "slick" advertising---sink-top or under-sink carbon filtration units will remove only a small portion of the incoming pollution from your tap water---and therefore do not qualify as "high purity " drinking water systems.

"High purity" home drinking water can only be produced by one of two types of systems: Steam Distillation or Reverse Osmosis. This article will focus on these two popular types of home water purifiers.

There is a continuing controversy in the health, nutrition and water purification fields about the comparative performance of these two systems. In virtually all of these situations, this confusion and controversy simply stems from an inadequate understanding of exactly what steam distillation and reverse osmosis(R/O) can and cannot do in treating our tap water.

Perhaps the most unfortunate part of this story is that many times both distillation and reverse osmosis manufacturers(and distributors) will make incredible claims of water purity for the particular system they happen to be selling.

This usually happens when a distributor sells only one type of purifier, thus making it very difficult for a customer to obtain truly factual information regarding the performance one can actually expect in the home with these two types of systems.

This article will summarize both the positive and negative aspects of both systems---thus providing some eye-opening facts which undoubtedly will be "omitted" from the average water purifier sales presentation.


The concept of reverse osmosis(or R/O) has been around for many years. Yet even today, with hundreds of scientific studies, papers and research efforts, the water purification industry still doesn't fully comprehend the mechanism which allows reverse osmosis to operate.

In nature, osmosis is the process by which plants(a carrot, for example) absorb moisture from the soil, purifying this moisture as it passes through the skin of the plant. During this absorption process, a measurable pressure exists across the skin of the plant, called the osmotic pressure. When this process is reversed, and pressure is applied to one side of a synthetic(man-made) membrane, we have the reverse of osmosis----or reverse osmosis.

The man-made R/O membrane, with it's dense material makeup will allow certain low molecular weight(very small) particles to pass through it. Larger, heavier molecules cannot pass through the membrane and are left behind and flushed away. If the pressure applied to the input tap water is properly maintained, the osmotic pressure of the membrane is overcome and small portions of purified water begin to "squeeze" through the membrane.

You can expect gradually decreasing water purity from the first day---since the membrane is susceptible to chemical and bacterial action as well as water pressure, temperature and pH(water acidity or alkalinity).


The actual performance of home-use reverse osmosis systems is the subject of considerable controversy. Water softening companies and reverse osmosis manufacturers make claims of extremely pure water(95-99% pure). Even reputable consumer magazines(Rodale Press, for example) appear to find that some systems will produce this water purity.

However, the cold hard facts of daylight spell out a considerably different picture. A consumer purchases a reverse osmosis system for a home environment, not a very carefully controlled laboratory experiment setup. Even recent articles written by reputable manufacturers for national water magazines are beginning to admit that these utopian purities are not attainable.

Newer technology(thin-film composite(TFC) membranes) achieves somewhat greater water purity than earlier technologies(cellulose acetate, cellulose triacetate, etc.) However these TFC R/O systems achieve this greater performance at the cost of increased membrane fouling and breakdown.

Reverse osmosis membrane fouling and breakdown is probably the most common problem we run into in the entire water business---this includes filtration systems(with their cadre of problems), reverse osmosis and steam distillation systems.

In fact, we have observed over the last ten years that by far the largest percentage of "dissatisfied water purifier owners" who we have talked with are owners of(or former owners of) reverse osmosis systems.

The new TFC membrane R/O systems are much more susceptible to oxidation and must incorporate some type of carbon pre filter to eliminate chlorine which would destroy the sensitive TFC membrane.

The watchword we conclude with is: if you choose an R/O system make sure that you select the right type of unit which is compatible with your water supply. If your area is served by a single water source, that determination should be quite easy.

On the other hand, if your area is served by several water sources where the ultimate water quality(chemical makeup) is variable and/or indeterminate, reverse osmosis, even with the latest technology, is a poor choice for consistently pure drinking water.

In commercial applications, exceptionally good water purity can be obtained using reverse osmosis when very high water pressure and very dense membrane materials are used. These conditions are found in large scale desalination and manufacturing processes.

In typical residential applications where "hard" water or high concentrations of salts and metals exist, higher water pressures are necessary to overcome the osmotic pressure of the dissolved concentrate in the incoming tap water. This suggests that some of the poorer locations for reverse osmosis would be hard water or rural areas with low or varying water pressures.


Every year, thousands of concerned homeowners invest hundreds of dollars in a reverse osmosis system. Virtually all of these individuals purchase these R/O systems not knowing some very important facts about the system.

MYTH #1: Reverse osmosis water costs you only a few pennies a gallon to produce.

TRUTH#1: To preserve any reasonable or moderate percentage of water purity(compared to manufacturer's claims), major portions of the system must be changed on a frequent basis.

When the cost of the filter and membrane changes are added to the cost of wasted water and plumber costs and divided into the number of gallons used by the homeowner over a period of one year(a realistic membrane replacement interval), the true cost per gallon will run between 25 and 35 cents per gallon. This is comparable with the operating cost of steam distillation systems.

MYTH #2: Membranes will last several years.

TRUTH #2: With good membranes running from $50 to $150 each(and some for "multi-level" marketing R/O units running up to $300 each), one can see why manufacturers are prone to "stretch the truth" about the expected lifetime of this expensive replacement item.

Even the newer TFC membranes(which are more expensive), tend to foul more easily than older technology, thus costing the homeowner even more money to keep his R/O system operating anywhere near the manufacturer's claims of water purity.

Few if any any reverse osmosis manufacturers(or distributors) provide performance data as a function of in-service operating time. Remember, the test data was obtained in a laboratory---not a homeowner's kitchen. The conditions and results are dramatically different---and reverse osmosis is a very "unforgiving" system under these conditions.

MYTH#3: Reverse osmosis will provide water that is 95-99% free of water-borne contaminants.

TRUTH #3: Reverse osmosis, when combined with a simple carbon filter WILL provide drinking water which is 98-99% free of ORGANIC CHEMICALS(chemicals which contain carbon(TCE for example); chlorine, free ammonia, etc.).

However, any carbon filter will do the same. In a home operating environment, R/O will remove only 50-80% of inorganic salts(sodium, etc) after a few months of operation.

In only rare cases do we find R/O systems removing in excess of 80% of dissolved solids(lime, sodium, heavy metals, etc) after a few months of in-home operation. The results obtained from testing hundreds of customer's water samples from in-home operating R/O units conclusively shows that manufacturer's claims for water purity are simply not being met.

Many times manufacturers will give sheets and sheets of test data showing extremely high equipment performance---and then in the small print we read "...the actual performance of (brand name) reverse osmosis systems may be less due to changes in water pressure, individual membrane efficiency, level of incoming contaminants, type of water contaminants, etc".

This is the manufacturer's "out" as they say---leaving you, the customer, holding the bag. The question here is, "...when you buy a water purifier, are you buying a system capable of providing specific in-home performance---or are you simply buying a bunch of test data sheets which do not relate to your home's water conditions."

Finally, the gradual degradation of the R/O water quality is difficult for the customer to detect, and by the time he or she decides to find out if the system is working, chances are the system is removing little or nothing---and the customer is drinking what amounts to tap water.


This very minute, hundreds of homeowners are attending "water seminars" at fancy hotels or are listening to salespersons selling reverse osmosis systems in their living room. The price tag for these "whole home water processors, water conditioners, water purifiers" or whatever name tag is being applied is many times outrageous.

Reverse osmosis is marketed primarily by water softening companies who "package" the R/O unit with a water softener and sell the combination as a "whole-house" water system for thousands of dollars. Prices of $3000-$4000 are common, with some companies boldly extracting up to $8000 for one of these systems.

Homeowners are mesmerized by the fast-talking, flashy multi-media, high-pressure presentations and many times don't know or are simply too shy to ask what may appear to be "stupid" questions about the system and it's performance. Not asking those questions(and getting truthful answers) is needlessly costing homeowners thousands of dollars every day.

Excellent, high-performance water softeners can be purchased for $800-$900 while a top-notch R/O system can be easily purchased for around $500.


Finally, remember that an improperly or poorly operating reverse osmosis system, coupled with a water softener, simply feeds high sodium concentrations directly to your "purified" water faucet.


The reverse osmosis concept has been applied to a multitude of industrial and medical applications.

Some years ago, the American Medical Association(AMA) published an extensive directory of medical concerns related to drinking water.

Prominent in these AMA findings was the fact that reverse osmosis was found to be CONCENTRATING the dangerous heavy metals mercury and aluminum. Mercury and aluminum have been linked with extensive neurological disorders.

We have conducted laboratory tests of a randomly selected reverse osmosis membrane operating on San Jose tap water and have found these AMA findings to be correct.

Nearly every municipal water system uses aluminum compounds(alum) in water treatment processes. Many shopping center vending machines(and some water stores) sell reverse osmosis water, using municipal tap water as a water source.


Who ends up buying a reverse osmosis system? Mostly it is an individual who has not comparison shopped and investigated the differences in price and performance between reverse osmosis and steam distillation.

In other cases it is a customer who has been given a "quick snow job" on water purification and who is too hesitant to throw the salesman out of the house or who capitulates to the "hard sell" seminar or in-home sales pitch.

Many of these individuals find it difficult to admit, even in the face of conclusive water tests on their system, that they have made a mistake, inasmuch as they have spent thousands of dollars on an "intelligent choice". We all make mistakes---however, this is one you don't have to make!

Reverse osmosis is a compact system, suitable for under-sink installation and capable of removing a portion of the incoming water contaminants. Beyond that, it becomes a "weak sister" in comparison to better performers such as steam distillation.

It should be obvious at this point that we do not have great things to say about reverse osmosis. Manufacturers are admittedly upset when facts such as those above are presented to potential buyers.

You have a choice---the truth now, or later.

There is a better alternative.



In the past, steam distillation has been primarily associated with steam irons, batteries, contact lenses, and the U.S. Navy. Today, however, in the face of increasing chemical, metal, biological and inorganic chemical concentrations in municipal and rural water sources, millions of individuals are turning to steam distilled water.

Millions of gallons are sold in supermarkets and water stores throughout the world, and untold millions of additional gallons are delivered to homes and offices. Entire countries(Panama, for example) live out their daily lives and operate their industries on distilled water.

Steam distillation relies on the physical principle of gravity to separate heavier inorganic salts from rising water vapor. As the water is boiled in a distiller, the steam rises, leaving salts(sodium, lime, etc), heavy metals(lead, mercury, etc), bacteria and other dissolved materials behind.

The pure steam vapors rising from the boiling water then enters a "heat exchange" system which cools the steam vapors back into water, distilled water, drop by drop.


Today we have many potentially toxic chemicals in our water supplies which vaporize at temperatures lower than that of water. To cope with this critical problem, most steam distillers use a "venting" system to allow "low boilers" such as chlorine a means to escape prior to the re condensation process.

Unfortunately, this venting process is inadequate to deal with the majority of "organic chemicals" such as TCE, pesticides, herbicides and other complex, man-made liquid and gaseous chemicals.

These organic chemicals are eliminated by a carbon prefilter which strips the organic chemicals from the incoming tap water prior to the boiling process.

The combined action of the carbon pre-filter and the subsequent steam distillation process then provides water which is consistently 98-99% pure. The key word here is "consistently". By comparison, reverse osmosis is at best 80-90% effective initially---with subsequent gallons of"purified" water progressively higher in concentrations of metals and salts.

It is important to note that the carbon filtration process precedes the distillation(or steam) process simply because a properly-designed purification process of any type leaves the last stage for it's cleanest process. Steaming provides that cleaner process. Carbon filtration is far less effective and thus is placed prior to the cleaner, steaming process.


Over the years it has been difficult to find any water purification system which has been so maligned and misunderstood as steam distillation.

Much of this undeserved reputation has been constructed by the manufacturers and distributors of filters and reverse osmosis products who find it difficult to sell their products on their own merits without maligning a better-performing product such as steam distillation.

MYTH #1: Steam distillation removes essential trace minerals from drinking water.

TRUTH #1: Much of this nonsense has been promulgated by reverse osmosis distributors who, if they thought about it, defeat their own system(if it works as effectively as they claim) with that argument.

That aside, the facts are that if one compares the trace minerals obtained by drinking several quarts of tap water daily with the trace minerals obtained with even a poorly organized daily diet of fruits, vegetables and animal products, only a small percentage(<2-3%)of these "essential minerals" is obtained from water.(2)

Water is therefore an unreliable and insignificant source of minerals. The American Medical Association and other prestigious organizations and authorities concur with this statement.(3)

Digging deeper into this "mineral issue", one finds that this small(2-3%) amount of minerals are basically indigestible by the body.(4) Unless specific amino acids or other bodily "catalysts" are present, the all-important process of chelation(pronounced "key-lay-shun") or bodily absorption is not conducted. This leaves the lime and salts to float throughout the body, clogging arteries, kidneys , joints and other digestive organs.(5)

MYTH #2: Steam distillation does not remove(but concentrates) certain toxic chemicals in the product water.

TRUTH #2: Again, this is a myth promulgated by distributors(and some manufacturers) of reverse osmosis and filtration systems.

For years, steam distillation systems have used carbon prefilters to remove toxic chemicals in the manner described in the previous section.

It is important to note that reverse osmosis itself does not remove these toxic chemicals, including chlorine, without the aid of an identical carbon filtration process.

MYTH #3: Steam distillation systems require extensive cleaning and are difficult to maintain and operate.

TRUTH #3: Early distillation systems were designed with few operator conveniences in mind. Cleaning was admittedly a problem. Boiling chambers were difficult to access and residue and scale removal was entirely thorough a small drain valve as shown in Figure 3.

Better engineered home distillers now incorporate removable boiling chambers with easy access for rapid and easy cleaning. The West Bend DOLFYN and DOVE systems incorporate these features.

MYTH #4: Producing pure drinking water by steam distillation is expensive and consumes large amounts of electricity.

TRUTH #4: Steam distillation uses electricity---reverse osmosis, by comparison, survives by replacing nearly 80% of the system on a yearly or bi-yearly basis. An honest comparison of the two systems, based on operating cost, finds them essentially equal.(6)

MYTH #5: Steam distillation systems require an excessive amount of space and are difficult to install.

TRUTH #5: In fact, steam distillation systems are most often located in the garage or basement, out of the way. A small pump delivers water through a small food-grade tube to a separate faucet on the kitchen sink(identical to reverse osmosis) and to the ice maker on the refrigerator.

Reverse osmosis, with it's multiple components and large storage tank, must fit under the sink area and, by comparison, is usually the more difficult to install based on available space.


As noted above, steam distillation systems fit most appropriately in a remote area such as a garage(or basement, if available). As shown in the Installation Diagram, the distilled water is pumped, on demand, to one or more separate faucets mounted on the kitchen(and perhaps bathroom) countertops as well as to appliances such as ice makers on refrigerators, water coolers or "instant hot" water dispensers.

Water delivery to these "remote" outlets is immediate and at adequate pressure to supply about one gallon of water per minute.


With about a half dozen reputable water distillers on the market today, prices for steam distillation systems has stabilized considerably. There are a few remnant "multi-level" distribution programs which price their systems several hundred dollars above competitively designed products.

In general, an "automatic" system capable of producing 8-10 gallons of pure distilled water per 24 hours and incorporation a moderately sized storage tank 5-10 gallons and the all-important heavy duty carbon(and sediment) pre filters will cost between $950-$1200.

Accessories to pump the water to remote outlets will run about $200. This includes tubing, faucets, ice maker adaptors, etc.

Most distillation systems sold today are of the "automatic" variety. Manual or "batch" distillers are also available for small families or portable operation where permanent attachment to house plumbing is not possible. These manual distillers run between $275 and $500, depending on manufacturer. Operating costs for manual distillers will be about 5-10 cents per gallon higher than fully automatic distillers.

Cleaning of any type of distiller will be easier when a water softener precedes the distiller. Unlike reverse osmosis, steam distillation can be relied upon to remove virtually all of the sodium salts placed into the house utility water by the softener. The "soft" water leaves no scale in the distiller boiling chamber and thus necessitates fewer and less vigorous periodic cleaning activities.


Making a decision on a high-purity home water system can be simplified when some of the key parameters of steam distillation and reverse osmosis are placed side-by-side. Table 1 summarizes those parameters which we have found most homeowners need in evaluating the comparative performance and benefits of steam distillation and reverse osmosis.

In the end, your final decision will reduce to the following issue: How important is the day-to-day purity of water produced by my home water purifier? If you can live with between 30-70% average removal of metals, salts and other dissolved contaminants, reverse osmosis may be your solution.

If on the other hand you want virtually totally pure(98-99% drinking water) consistently, day in and day out, steam distillation with carbon pre-filtration is the answer.

The initial and operating costs of the two types of systems are nearly equal. What is dramatically different is the actual performance you will obtain in your home, day after day, year after year. The steam distiller is the clear winner.

Finally, if you have a really tough water environment, with bacteria, nitrates, iron, manganese, sodium, lots of lime or other major problems, reverse osmosis literally begins to fall apart at the seams at day one.

Steam distillation, on the other hand, will provide the same, consistently high purity level water under the most adverse conditions as produced under relatively "clean" tap water conditions.

It is no wonder the U.S. Navy and ocean-going vessels and submarines around the world choose steam distillation to recover completely pure drinking(and bathing) water from raw sea water.


Many of those who read this booklet will already own or are seriously considering purchasing a home-use reverse osmosis unit. Some of the information presented on reverse osmosis may come as a shock to those individuals. A natural question will be: "Well, why didn't the reverse osmosis salesperson tell me about all these aspects of reverse osmosis?"

The simple answer is: if the customer knew the full story behind reverse osmosis---it's positive and negative aspects, chances are there would not be a sale!

We need to remember that the majority of companies who market reverse osmosis are in the water softening business---and not in the drinking water "purification" business.

The focus of these two business areas is considerably different---one experienced in working with "utility water"(water softeners) in the home---the other concerned with the healthful aspects of drinking water.

Thus, what may be "acceptable" water purity to someone in the water softening business may be completely inadequate for someone searching for drinking water totally free from unwanted contaminants.

Decide how pure you want your drinking water---you have then selected the technology to do the job. It's that simple.












































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