There’s No Such Thing As "Pure" Water

 by James P McMahon, Ecologist

There’s no such thing as pure water.  The entire concept of pure water is misleading and needs to be cleared up.  I was reading an interesting note in the October (’05) issue of Smithsonian about harvesting icebergs as a source for bottled water and vodka.  In the article, David Sacks, president of the Canadian Iceberg Vodka Corporation is quoted as saying it is ‘the purest water in the world’.  That got me thinking and wondering if that source is as pure as the people who sell it claim it to be. 

People buying bottled water are often under the impression that they’re purchasing water that is pure.  Generally it has been treated.  Whether or not it is pure is another matter entirely.  And those people considering water purification or filtration have been led to think that pure water is something they should strive for in their homes.  Many water treatment dealers and some health practitioners claim that either distilled water or water from Reverse Osmosis is ‘pure’.  I don’t agree.

Distillers use heat to turn water into steam.  The steam rises, leaving any contaminants behind.  That’s the theory.  Gases, some chemicals, and volatile organic compounds can travel with the steam.  Distillers use activated carbon to capture these pollutants and for the most part that works.  Still, some contaminants can remain.  Chloramine is an example of one contaminant that is not eliminated by this process.  There are others.

Distillation does remove more contaminants than any other single process.  The real issue for those considering distillation is that it lowers the pH of the water it produces, thus rendering it acidic and less than optimum for health.  Distillers are inconvenient, waste a considerable amount of water and are expensive to use but they do produce the closest thing to pure water.

Reverse Osmosis is the term used to describe a rubber membrane said to allow the passage of water at the molecular level.  Water is forced through the membrane leaving contaminants behind.  Once again though, gases, some chemicals including chloramine and one form of arsenic, and some bacteria can pass through the membrane.  Some people claim the membrane becomes less effective with age.  A ‘polishing’ filter of activated carbon is used to capture the gases and volatile organics. If your city uses chloramines to treat your water you’ll need to use catalytic carbon in this stage to remove it. 

The Reverse Osmosis membrane is typically one component in a kitchen treatment system consisting of several treatment stages, ranging from one to three.  One manufacturer has recently come out with a seven stage RO unit, only one stage of which is the RO itself.  So, if RO is so thorough, why seven stages?  The fact is that ‘Reverse Osmosis’ or ‘RO’ are terms that are carelessly tossed around to describe what is in fact a multi-stage treatment system of which RO might be one component.

There are other issues with reverse osmosis that the public is generally unaware of.  First, it too lowers the pH of water.  Any process that removes the minerals from water will create water that is ‘aggressive’ in that it will seek to replace those minerals.  Both distilled and RO water become acidic upon exposure to air.  The carbon dioxide in air reacts with the water, filling the void once filled by minerals or contaminants.  There are ways to address this issue but nonetheless the systems that most of you purchase do not address it and produce an aggressive low pH water.

Another issue with reverse osmosis systems is bacterial growth in the water storage reservoir.  These bacteria are said to colonize the tank from the faucet side of the RO system.  Others suggest that unless your RO system has a UV light that living bacteria squeeze through the rubber membrane and colonize the holding tank.  In either case, once they do colonize the RO water tank every drop of water is contaminated. 

Testing has shown that the bacteria that colonize carbon filters and RO systems are generally heterotrophic populations, which means that they are not a health hazard.  Still, my point is that RO systems DO NOT remove all they claim to.  And who wants to drink bacteria when the point was to purify the water in the first place?

Implicit in the use of the term ‘pure’ water is the suggestion that the water has nothing in it.  However, water in its natural state has mineral content.  When you remove those minerals you create a highly reactive water that will interact with the first organic material it encounters, including air or plastic.

Other water purification systems contain a variety of treatments that are effective at removing certain contaminants.  Again consumers may purchase the wrong product by failing to determine which treatments meet their needs.  In any case, the end result is water that has been treated or cleansed of contaminants.  It’s still not pure.

There’s no such thing as pure water.  To think that you can purify water using one of these technologies is misleading.  The very concept of ‘pure’ water is misleading.  Pure water does not exist in nature.

Water is the universal solvent.  Even as it falls to earth as rain it picks up particles and minerals in the air.  And as soon as it hits the ground it captures minerals from the soil and rock upon which it lands.  It makes its way into streams and rivers, carrying soil from the mountains to the sea. 

Nowadays water picks up contaminants such as airborne mercury while it’s falling as rain. 

What you can do is to remove contaminants from your water and you can determine how extensive you’d like to be in that effort.  The approach I suggest is to learn what’s in your water, set your goals, and then identify the technologies that will remove the contaminants that enable you to meet your goals. 

Consumers can achieve healthy water by identifying the unhealthy contaminants in their water and then taking action to remove them.  In general, the public discussion about water can and will switch from the notion of ‘pure’ to ‘healthy’.  Healthy water is attainable, whereas pure water is not.

And just what is healthy water?  I would suggest to you that healthy water has an optimum pH of 7.2 to 7.6.  Harmful contaminants such as chlorine, chloramines, disinfection by-products such as the trihalomethanes, and any harmful chemical or metals whether man made or naturally occurring have been identified and removed with the appropriate treatment.  Healthy water contains minerals.  If you’ve tested your water you’ll see these as calcium and magnesium.  There may be trace amounts of others as well.  I’ll go into greater detail about the make up of healthy water in my next paper.

Back to the iceberg…is that water pure?  Certainly the top layers would be just as contaminated as any other water subjected to the fallout of modern day airborne pollutants.  I’m not sure I’d want to drink the layers formed after we dropped the atomic bombs on Japan.  And what about the layers formed during the Industrial Revolution when pollution was at its height? 

Theoretically I guess the ice formed many thousands of years ago would be free of human contaminants, but is that water pure? Is it free of dirt and dust from wind storms and the metals titanium or uranium from times long ago when meteors slammed into the earth?

Do icebergs contain pure water?  I seriously doubt it.

Source: Sweetwater