Not all water filters were created equally. Find out
what a micron is, and why they are so important to water filters.
Microns and Water Filters
A micron, as defined by dictionary.com is:
“Also called micrometer. The
millionth part of a meter. Symbol: μ, mu.”
In slightly more understandable terms, one millionth
of a meter works out at 0.0001 cm or 0.001 mm.
A human hair is around 0.0889 mm and there are 25,4000
microns in one inch.
You might ask what this little science lesson has to
do with water filters?
Well most filters can have their effectiveness at
removing pollutants measured by how low their micron score is.
For example, a water filter that protects down to 1
micron, will block any particles larger than this from passing through.
Anything smaller than 1 micron may continue through
and be part of your drinking water.
Water pollutants come in a variety of shapes and
sizes, and by knowing exactly what you’re looking for, you stand a much greater
chance of stopping it.
The table below shows some common water pollutants and
their sizes in microns.
Water Pollutant Particle
Size (Microns)
Mold
Spores 10
- 30
Asbestos
0.7 - 90
Insecticide 0.5 - 10
Bacteria
0.2 - 10
Lead
0.1 - 0.7
Viruses 0.004 - 0.1
Note the size of virus particles. These include E-coli,
hepatitis, and legionnaires disease.
For a water filter to protect against the smallest
virus particles, it would need to have a filter capable of working down to
below 0.004 microns.
Actually, to be guaranteed protection then an ultraviolet
filter would be needed too.
The only methods of home water filtration that work on
this scale are reverse osmosis, and distillation.
Now water distillation cannot be measured in microns,
but reverse osmosis can.
An RO membrane can filter down to an amazing 0.0001
microns or 0.00000001 cm.
Compare this with the most effective whole house
filter that I am aware of, the Aquasana Rhino, which fights water contaminants
down to 0.35 microns, and a typical carbon filter which could work from
anywhere between 0.5 – 20 microns.
Each system has it’s positive and negative aspects,
and the micron rating is not the only thing to be considered when buying a home
water filter.
For example, a problem with chlorine would not require
such strict filtration. Be aware though, that just any old water filter will
not be a solution to water pollution for every problem.
Certain contaminants will only be removed by certain
water filter types.
Make sure you know exactly what is wrong with your
water before you commit to buying a home water filter
My name is Jon Godfrey, and I am
the creator of Water Filter Answers.
With the advent of fracking and the
increasing threat of pollution encroaching further into our lives, it has never
been more important to regulate our daily drinking water.
We provide information on the impact that
water filters may have on your drinking water. By explaining the science and
breaking down the terminology, we hope that we can help you make the most
informed decisions for your health.
We recognize that there are many ways to
filter drinking water, and we want to show you the best method for each situation
and budget. Aside from our extensive reviews of water filter systems, we also
regularly publish informative articles on water quality and pollution.
We can counteract the effects of water
pollution, but more importantly, we should try to reduce our impact on the
environment.
"I've been taught
that distilled water is the purest that one can drink. On the original article
you write that this is not a safe assumption. How so?"
Distillation does purify water, but it
can't remove all contaminants. Actually, distilled water can be very impure.
Consider how distillation works. First, you're basically boiling
water and then letting it cool to collect it again.
Ideally contaminants with different boiling points will be
removed, if you are careful to collect the distilled liquid at exactly the
right temperature and pressure.
It's not as easy as it sounds. Plus, there are contaminants that
won't separate from the water just from vaporization.
Sometimes the distilling process actually adds contaminants that
weren't originally present, from the glassware or metal components.
For distilled drinking water, keep in mind even if the distillation process is
scrupulous, impurities come from the container into which the water is placed.
Heavy metals are used to stabilize packaging plastics and
can leach into the water over time.
For that matter, plastic monomers coat a new container and
become a part of bottled water.
Anne
Marie Helmenstine, Ph.D.
Ph.D. in
biomedical sciences from the University of Tennessee at Knoxville - Oak Ridge
National Laboratory.
Science
educator with experience teaching chemistry, biology, astronomy, and
physics at the high school, college, and graduate levels.
ThoughtCo
and About Education chemistry expert since 2001.
Widely-published
graphic artist, responsible for printable periodic tables and other
illustrations used in science.
Experience
Anne
Helmenstine, Ph.D. has covered chemistry for ThoughtCo and About Education
since 2001, and other sciences since 2013. She taught chemistry, biology,
astronomy, and physics at the high school, college, and graduate levels.
She has worked as a research scientist and also abstracting and indexing
diverse scientific literature for the Department of Energy.
In
addition to her work as a science writer, Dr. Helmenstine currently serves as a
scientific consultant, specializing in problems requiring an interdisciplinary
approach. Previously, she worked as a research scientist and college
professor.
Education
Dr.
Helmenstine holds a Ph.D. in biomedical sciences from the University of
Tennessee at Knoxville and a B.A. in physics and mathematics with a minor
in chemistry from Hastings College. In her doctoral work, Dr. Helmenstine
developed ultra-sensitive chemical detection and medical diagnostic tests.
ThoughtCo
and Dotdash
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reference site focusing on expert-created education content. We are one of the
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measurement company. Every month, more than 13 million readers seek answers to
their questions on ThoughtCo.
For more
than 20 years, Dotdash brands have been helping people find answers,
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Why can't we
convert salt water into drinking water?
BY NICHOLAS GERBIS
It seems strange that water
should be such a scarce resource when our planet is drenched in 326 million
trillion gallons of the stuff.
But it turns out that less
than one-half of 1 percent of it is drinkable.
Out of the rest, 98 percent
is oceanic salt water and 1.5 percent remains locked up in icecaps and
glaciers.
The
stark irony of Samuel Coleridge's immortal line "Water, water, everywhere / Nor any drop to drink" is
manifest each year in coastal disasters around the world, like Hurricane
Katrina, the 2004 Indonesian tsunami and the 2010 Haiti earthquake, as people
within sight of entire oceans are threatened with dehydration.
Between droughts, natural
disasters and the large-scale redistribution of moisture threatened by climate
change, the need for new sources of potable water grows with each passing day.
Each year, the global
population swells by another 85 million people, but worldwide demand for
freshwater increases at twice the rate of population growth, doubling every 20
years or so.
Throughout the world, our
most vital resource is under stress from pollution, dam construction, wetland
and riparian ecosystem destruction, and depletion of groundwater aquifers, with
poor and marginalized populations getting the worst of it.
So why can't we convert
seawater into drinking water?
Actually, we can and we do.
In fact, people have been
making seawater drinkable at least as far back as the ancient Greeks.
But when taken to the scale
of cities, states and nations, purifying seawater has historically proven
prohibitively expensive, especially when compared to tapping regional and local
sources of freshwater.
However, as advancing
technology continues to drive costs down and freshwater continues to grow
scarcer and more expensive, more cities are looking to seawater conversion as a
way to meet this vital demand.
Read on to find out how and
where seawater is being converted into drinking water today, including how
desalination is bolstering disaster relief in Haiti.
How and where is desalination used today?
Desalination
has come a long way in the 2,400 years or so since people boiled salt water and
collected the steam in sponges.
Yet, the most widely used
method is still based on the same principle: distillation.
Essentially, distillation
artificially mimics what occurs in nature: Heated water evaporates to become
water vapor, leaving salts and impurities behind, and then condenses as it
cools to fall as freshwater (aka rain).
Distillation plants refine
and speed up this process by applying artificial heating and cooling and by
evaporating water under lower air and vapor pressure, which significantly
reduces its boiling point.
This method requires a great
deal of energy, however, so distillation plants are often located alongside
power plants, where waste heat is available to bring the water up to a volatile
temperature.
Another method, reverse osmosis (RO) desalination, uses pressure to force water
through filters, straining out other substances at the molecular level.
Developed in the 1960s, the
process became feasible on a commercial scale in the 1970s, ultimately
replacing distillation as the method used in most new desalination facilities,
in part because it requires less energy.
Besides removing salt, both
methods remove virtually every mineral and most biological or organic chemical
compounds, producing water that is safe to drink, far exceeding federal and
state drinking water standards.
So
how widespread is desalination?
Specific
figures are elusive, as new plants are constantly being added and little data
exists concerning plants that have shut down.
It's
also tricky to separate counts of distillation versus RO plants.
However,
a good ballpark figure is 8,000 RO seawater desalination plants globally
producing a total of about 10 billion gallons (37,854,117 cubic meters) of
drinking water each day, with older distillation plants still outnumbering RO.
The
largest users of desalination globally in terms of volume capacity are (in
descending order) Saudi Arabia, United Arab Emirates, United States, Spain,
Kuwait and Japan.
Desalination
provides 70 percent of drinking water in Saudi Arabia.
Within
the United States, Florida, California, Texas and Virginia are the largest
users, and the country as a whole has the capacity to desalinate more than 1.4
billion gallons (5.6 million cubic meters) of water per day.
To
put that in perspective, that equates to less than 0.01 percent of municipal
and industrial water use nationwide.
Cruise
ships, submarines and ships of war have been using desalination for decades.
One
impressive example, the aircraft carrier U.S.S. Carl Vinson, can make some
400,000 gallons (1,514 cubic meters) of its own freshwater every day, half of
which is excess water that at press time is being used to aid disaster relief
in Haiti.
As
much as desalination has increased over the years, it is still just a drop in
the bucket.
In
this next section, we'll look at what's holding us back from a full-on sea
change in freshwater supply.
The Cost of Desalination
There's little doubt that the world needs
more drinking water.
It's
also abundantly clear that the need will keep pace with mounting population
growth and the pressures brought about by global climate change.
In
the United States alone, experts agree that water demand already exceeds
supply, projecting that 36 states will confront shortfalls within the next
three years.
Within
15 years, almost 2 billion people globally will live in areas confronting water
scarcity, and, according to most model scenarios, such shortfalls will only
worsen under climate change.
Indeed,
the availability and distribution of water is widely discussed as a likely
determining factor in future global stability.
So, what is holding
us back from diving in headfirst? Until recently, purifying seawater cost
roughly five to 10 times as much as drawing freshwater from more traditional
sources.
RO
filters have come a long way, however, and desalination today costs only half
of what it did 10 to 15 years ago.
Consequently,
transportation, energy and environmental costs have now replaced technology as
the primary impediments to large-scale desalination.
Energy consumption
accounts for as much as one-third of the total cost of desalinated water,
making even coastal plants expensive to operate.
Inland
states must also grapple with the sizeable expense of transporting seawater
inland.
They
can opt to use local brackish (salty) water sources, instead, but then they
face a different problem: how to dispose of the byproduct, a concentrated salt
solution that coastal sites have the luxury of pumping back into the ocean (a
practice that remains controversial in environmental circles).
Zero
Liquid Discharge (ZLD) plants are one way out, but they drive up the energy
costs of what is already an energy-intensive process.
Is
desalination cost-effective? The answer probably depends on where you live.
Given
the high costs of freshwater importation and reclamation, desalinating seawater
is an increasingly attractive option for water-stressed areas.
The
potential for desalination is limited mostly by social, political,
environmental and economic considerations, which vary from place to place.
Any
way you look at it, the rising tide of desalination seems likely to remain a
growing part of our water portfolio for years to come.
Desalination is the process of removing salt from water.
.
At its root, it is a very simple process. Water is boiled off and condensed on another surface, leaving the salt behind in the original container. This is called distillation.
.
Reverse osmosis is another method of desalination which forces water through a very fine filter that prevents the salt from passing through.
.
Desalination has many benefits, but there are downsides to the process that also need to be considered.
LIST OF PROS OF DESALINATION
1. Saltwater Abundance
.
In many areas of the world, fresh water is in short supply. Salt water, on the other hand, is very plentiful.
.
Desalination turns salt water into fresh water, which is invaluable for people who have no other source of water or whose main source is failing them. This water can then be used for drinking or for agricultural needs.
.
When most people think about a water shortage, they think about not watering their lawn or washing their car.
.
But to a farmer, water rationing can be devastating. In the world’s arid regions, irrigation is absolutely necessary for growing many of the local crops.
.
Not having these crops to sell has an enormous detrimental effect on the economy. A shortage of fresh, locally grown produce can also impact the diets of residents.
.
All in all, having to forbid farmers from irrigating their crops does not work out well for anyone. Desalination can make that entire chain reaction unnecessary by providing the water that farmers need for their crops.
2. Not Dependent on Changing Factors
One of the greatest problems with many proposed solutions to the growing water demand is that they are dependent on uncontrollable factors.
Building more reservoirs presupposes that there is going to be the rain or snowfall needed to fill them. Desalination does not rely on anything other than the presence of the ocean.
With the concern surrounding the melting of the polar ice caps and the rise of the ocean levels, nobody is concerned about the ocean disappearing anytime soon.
3. Reliable Technology
Unlike many of the proposed technologies for dealing with emerging problems in the world, distillation and reverse osmosis are not in the research stage.
They have been proven and used for years for a variety of applications, including water purification. Neither method is volatile or risky.
People who argue for desalination as a way to combat drought conditions strongly emphasize the point that we have the technology at hand to address the problem and that we know how to use it.
This is not a pie in the sky dream of what might be possible someday. It is a workable solution.
https://youtu.be/2XMRlFMJB-g
i
LIST OF CONS OF DESALINATION
1. Energy Costs
The main problem with desalination is that it takes an enormous amount of energy.
Distillation requires heating countless gallons of water to boiling temperature before it can be recollected and used.
Reverse osmosis is no better. Osmosis is a natural process. Reversing it is very energy demanding.
People who oppose desalination as a workable solution for the drought problem facing various regions of the world argue that the energy costs are simply too high for it to be a long term, sustainable solution.
2. Expense
Desalination plants do not just use up a lot of energy, they also use up a lot of money.
Building the plant creates a very large cost upfront that many of the poorer sections of the world simply cannot afford. There is then the added expense of providing the energy to keep the plant operating.
Research in the U.S. has found the desalinated water costs five times as much to harvest as other fresh water sources. This cost is eventually passed on to the consumer, many of whom cannot or would not pay that much for their water.
There is a functional desalination plant in Santa Barbara, California, but that water is specifically held in reserve for emergency use only because the water is simply too expensive for people to buy as long as they have any other option.
The technology to do so is fully understood and can be used today, not after years of additional research.
Unfortunately, it takes enormous amounts of energy to drive these plants. The price of that energy ends up making desalinated water cost prohibitive.
If there were a source of cheap, renewable energy that could be utilized in the process, it would be a much more manageable solution.
As it currently stands however, it looks like desalination is going to continue to be held in reserve for emergency purposes only.
3. Waste
The whole point of the desalination process is to remove salt from water. This leaves the producers with large amounts of brine on their hands that have to be disposed of in some way.
Chlorine and anti-scaling agents are often added to the water and then left behind in the brine. Dumping this waste back into the ocean plays havoc with the ecology and kills marine life.
The other by-product of desalination is carbon emissions.
The huge amounts of energy used in the process create an equally large amount of emissions that are released into the atmosphere and damage the ozone layer.
Desalination is a proven and effective way of turning saltwater into freshwater that is usable for drinking, livestock, and irrigation.
The technology to do so is fully understood and can be used today, not after years of additional research.
Unfortunately, it takes enormous amounts of energy to drive these plants. The price of that energy ends up making desalinated water cost prohibitive.
If there were a source of cheap, renewable energy that could be utilized in the process, it would be a much more manageable solution.
As it currently stands however, it looks like desalination is going to continue to be held in reserve for emergency purposes only.
Unfortunately, it takes enormous amounts of energy to drive these plants. The price of that energy ends up making desalinated water cost prohibitive.
If there were a source of cheap, renewable energy that could be utilized in the process, it would be a much more manageable solution.
As it currently stands however, it looks like desalination is going to continue to be held in reserve for emergency purposes only.
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