13 types of water purification and filteration systems
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13 Types Of Water Purification And Filtration Systems
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Clean drinking water is a matter of life and death. Our human body consist of 50-
70% water and the quality of water which we consume matters because unclean
water is a sure predictor of shortened life expectancy. Although we may have the
luxury of access to fairly clean water, there are still chemicals and contaminants
in our water supply. The safest is to take matters into our own hands. Understand
how each of the 13 types of water filtration and purification method works below
and apply it to your home to get the best possible quality of drinking water that
you can afford.
According to a recent United Nations report, unclean water is a sure predictor of
shortened life expectancy. The importance of clean water cannot be overstated.
1. Boiling
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Is the most commonly used method to purify water. Water that is to be boiled
should always be clear. It is easier with a kettle as it whistles once it is ready to
be turned off. Otherwise if using other types of simple container, once boiling,
you should continue for about 2 to 3 more minutes before removing the heat.
Pros
o Kills almost every living thing and vaporizes most chemicals.
Cons
o Metals become more concentrated.
2. Slow Sand Filter
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Also referred to as biosand or biological sand filter. A slow sand filter is
comprised of a bed of graded sand which is supported by a layer of gravel. This
filter media is confined in a box with openings at both ends allowing water to flow
in and out, while operating on a top-down, gravity basis.
Pros
o Solids and water muddiness is naturally filtered.
Cons
o Some bacteria still remains.
3. Fiber Filter
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These filters contain cellulose, rayon or some other material spun into a mesh
with small pores. It is just like pouring water containing sand through a piece of
cloth. Unlike slow sand filter, pressure is applied to force water through tightly
wrapped fibers. There are many kinds of fiber filters in the market that comes in
a variety of shapes and sizes from fine to coarse meshes. Go for fiber filters with
micron ratings lower than 1 to efficiently trap particles.
Pros
o Sediment and muddiness is removed.
o Small organic particles that causes bad odors and taste may also be
removed.
Cons
o The lower the micron ratings, the more often the filter must be
changed.
o Anything that is dissolved in water like chlorine, lead and mercury is
not removed.
4. Ceramic Filter
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Almost exactly like fiber filters which will provide only mechanical filtration.
Again, go for pore sizes that are less than 1 micron. 0.5 micron if possible.
Pros
o Reduces asbestos fibers that may come from the degradation or
breakdown of human-made products such as insulation, pipes, etc.
o Works against certain bacteria.
Cons
o Chlorine, lead, mercury and other organic compounds stays in the
water.
Activated Carbon / Charcoal Filter
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Charcoal is carbon. Activated charcoal is charcoal that has been treated with
oxygen to open up millions of tiny pores between the carbon atoms. The use of
special manufacturing techniques results in highly porous charcoals that have
surface areas of 300-2,000 square meters/gram. These activated charcoals are
then used to adsorb substances from liquids. Adsorb basically means attaching
by chemical reaction. Activated charcoal with a fairly wide surface area has
countless potential for bonding chemicals to the surface. Activated charcoal is
good at trapping other carbon-based impurities, as well as things like chlorine.
Many other chemicals like sodium and nitrate are not attracted to carbon at all so
they pass right through. This means that an activated charcoal filter will remove
certain impurities while ignoring others. It also means that, once all of the
bonding sites are filled, an activated charcoal filter stops working. At that point
you must replace the filter.
5. Granular Activated Charcoal / Carbon Filter
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Although activated charcoal granules are loose, they are an effective and
valuable water treatment device. As long as a uniform flow rate is maintained
and the filter is changed according to the manufacturer’s specifications, optimal
performance is achieved.
Pros
o Reduces chlorine, particles and improves the taste and odor of water.
o Water flow is reasonably maintained and is suitable for use as a whole
house filter.
o Typical filter cartridge changes are done annually.
o Zero electricity is used.
o Zero water is wasted.
o Beneficial minerals such as calcium, magnesium and potassium that
are dissolved in the water, stays in the water.
Cons
o Water can flow around the granules without being treated as water
flows where there is less resistance.
o Water can carve a channel where it may flow freely with little
resistance, avoiding contact with the filtration medium.
o Pockets of contaminants can form around the granules that will result
in a collapse, which contaminates the filtered flow of water, as the pressure
changes.
o General pitcher filters containing active carbon granules have fairly
large effective pore sizes of more than 20 microns.
o May potentially become breeding grounds for trapped bacteria when
water flow is at a stop.
6. Solid Block Activated Carbon / Charcoal Filter
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Unlike granular activated charcoal, the carbon has been specially treated,
compressed and bonded to form a uniform matrix. This combination of features
provides the potential for greater adsorption of many different chemicals and
greater particulate filtration than other types of purification methods. Effective
pore sizes are usually below 1 micron. Just like any other filter cartridges, it will
eventually become plugged and has to be changed according to manufacturer’s
specifications.
Pros
o Certain filters are designed to better reduce specific contaminants like
arsenic, lead, mercury, etc.
o Much more effective and complete than granular activated carbon
filters as surface area is larger and contact time is longer.
o Pore sizes of 0.5 micron and below is small enough to prevent trapped
bacteria from multiplying.
o Totally independent of electricity and water pressure.
o Nutrient from minerals like calcium, magnesium and potassium remain
in the water.
Cons
o Soluble salt like nitrate and fluoride is not naturally reduced.
o Potentially harmful minerals like cadmium is not naturally reduced.
7. Reverse Osmosis
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Reverse osmosis is a separation process that uses pressure to force water
through a membrane with really tiny microscopic holes that retains contaminants
on one side and allows pure liquid to pass to the other side. 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.
Pros
o Salt and inorganic matter is greatly reduced. If a carbon filter is used
for post filtering, the quality will almost be as good as distilled water.
o Parasites and viruses are completely removed in properly functioning
units.
o More treated water is produced compared to distillation.
o No electricity is used. Money saved.
o A proper reverse osmosis membrane lasts you at least 3 years. Money
saved.
Cons
o The speed of water produced may not be enough for other uses other
than drinking like cooking, washing, cleaning, etc.
o About 3 drops of water is wasted for every 1 drop of filtered water
produced.
o Organic chemicals may still linger in reverse osmosis treated water.
o The membrane’s efficiency becomes unpredictable to factors like
contaminant concentration, chemical properties of the contaminants, membrane
type and quality, water acidity levels, temperature and water pressure.
o In situations where high water pressure is not present to force water
through the membrane, it will not work.
o The pre and post filters that come with most reverse osmosis systems
require changing periodically according to manufacturer’s recommendation.
o The storage tank requires regular cleaning to ensure the high quality of
water stored.
o Damaged membranes are hard to notice, thus it is not easy to tell if
the system is still functioning properly.
8. Distillation
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Distilled water is pure water that is obtained in a process that captures the pure
steam from boiling water, which turns to liquid form again through condensation.
A vapor trap, carbon filter, or other device should be used along with a distiller to
ensure a more complete removal of contaminants.
Pros
o Very pure water is captured.
o Removes salt, minerals, metals, chloride and others that carbon fails to
discard.
o Bacteria, viruses and protozoa is killed or left behind when water
evaporates.
o Regardless of the quality of the entering water, the end result will
always be high quality treated water.
o Unlike filters, there is nothing to replace.
Cons
o Long hours are required to attain a substantial amount of water. For
example, it may take half an hour or longer to get 1 cup’s worth (250ml / 8.5oz) of
distilled water.
o A lot of electricity is used. For example, it may cost around 0.35 cents
worth of electricity to produce 1 gallon / 4 liters of water, which adds up to about
$21 per month for 2 gallons per day.
o Water cannot be distilled in the absence of electricity, making it
completely unattainable should an emergency arise.
9. Chlorine Bleach
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Chlorination is the process of adding the element chlorine to water as a method
of water purification to make it fit for human consumption as drinking water.
Water which has been treated with chlorine is effective in preventing the spread
of waterborne disease.
Pros
o Cheap.
o Commonly available in supermarket, pharmacies and convenient
stores.
o Effective against bacteria and viruses.
Cons
o Initial chemical contamination in the water is not affected.
o Increases cholesterol formations.
o Carcinogenic in large amounts.
o May cause heart diseases because in the blood, chlorine reacts with
calcium which causes it to become toxic and non soluble. Then it becomes plaque
(breeding ground for bacteria) that eventually builds up in the body.
10. Iodine
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The most common chemical purification method used by campers. With the
proper iodine concentration and a 30-minute contact time in moderately turbid
water that is maintained at 20C / 70F or higher, all harmful bacteria and most
viruses will be destroyed.
Pros
o Effectively kills viruses, bacteria and protozoa.
o Lightweight and convenient.
Cons
o Does not effect the cryptosporidium protozoa that can cause
gastrointestinal illness with diarrhea.
o The colder the water, the more the time is needed for proper
disinfection.
o Does not change the clarity of water but changes the taste.
o Iodine is only practical for short term use.
11. Ozone / O3
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O3 is an unstable molecule which readily gives up one atom of oxygen providing
a powerful oxidizing agent which is toxic to most waterborne organisms. Ozone is
made by passing oxygen through ultraviolet light or a ‘cold’ electrical discharge.
To use ozone as a disinfectant, it must be created on-site and added to the water
by bubble contact.
Pros
o Inactivates harmful protozoa that form cysts.
o Effective against most bacteria, virus and microorganism.
o Produces less dangerous byproducts than chlorine.
Cons
o Produces trace amounts of a type of carcinogen called bromate.
o No disinfectant residual is left in the water.
12. Ultraviolet / UV
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Water passes through a clear chamber where it is exposed to Ultraviolet 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.
Pros
o Very effective at inactivating cysts.
o Zero toxic byproducts.
o No added smell and taste to treated water.
o In fact, taste will improve as organic contaminants are destroyed.
o Requires very little contact time.
o Many types of bacteria, virus and microorganism are wiped off.
o Beneficial minerals are not affected.
Cons
o UV light’s disinfection effectiveness decreases as the water gets
muddier, a result of the absorption, scattering, and shadowing caused by the
suspended solids.
o Just like ozone, no residual disinfectant is left in the water, prompting a
need to add a residual disinfectant.
o Anything that is not ‘alive’, like lead, asbestos and chlorine, are not
affected by ultraviolet light.
o Will not operate without the presence of electricity.
13. Solar Water Distiller
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A clear plastic barrier like a plastic bag, ground cloth, or a plastic grocery sack is
placed over the water source. The sun passes through the barrier and heats the
source which then vaporizes, rises and then condenses on the underside of the
plastic barrier. The moisture collected is drinking water.
Pros
o Capable of distilling almost any tainted water including seawater.
o Drinkable water can be condensed from anything that has moisture.
o Easy to make and has low impact on the environment. All that is
needed is a container to catch water and a large sheet of clear plastic.
Cons
o Source materials that give off toxins like radiator fluids or fuels are not
distillable.
o The distilling process is extremely slow and only small amounts can be
collected daily.
o Wild salmonella reproduces quickly when stored in the dark, requiring
10 parts per million of hydrogen peroxide to solve the issue.