Before we start, lets decide what it means for
something to be clean. Lets say that by
clean, we mean safe to drink. Some of the
impurities that can be found in water include
chlorine, lead and asbestos from old pipes, and
bacteria and the amount of these impurities
depends on where you get the water.
Water that is found outside in places like
lakes and ponds has a lot of bacteria in it,
which can make you sick. In order to kill this
bacteria, the people in charge of making water
safe to drink add chlorine (its also used in
swimming pools, though the weird smell comes when
there's not enough chlorine). If your water is
provided by the city, there's a small amount of
chlorine in the water that comes out of your
faucet at home.
Even though chlorine is put in water to make it
safer to drink, it can produce things that are
harmful, and that smell and taste bad. Most of
the water filters that you can find at the store
are good at removing chlorine and the bad things
it produces by using something called activated
carbon. Activated carbon is basically
charcoal with a bunch of tiny holes in it. This
is how it works.
When you pass water with chlorine through
activated carbon, the chlorine would much rather
grab on to the carbon than stay in the water.
This process of sticking is known as
adsorption, and the tiny holes in the
activated carbon provide more places for the
chlorine to stick, which leads to cleaner water.
Activated carbon is also good at adsorbing things
other than chlorine, and doctors use it to treat
people who've consumed certain poisons.
Unfortunately, activated carbon doesn't kill
bacteria , and once its fully covered by
adsorbed impurities, it stops working! Though it
is best to use water that is been cleaned by the
city, in an emergency you can boil rain water, or
water from lakes, ponds, or rivers. Boiling
water for several minutes will kill most of the
bacteria. However, other impurities such as
metals and other chemicals may still remain.
These can be removed through distillation.
In distillation, the water vapor from the
boiling water is collected, cooled, and turned
back into a liquid in a separate clean container.
I hope this helps answer your question. Here
is a good online resource I used, and I recommend
it in case you'd like to learn more:
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