Desalination of sea water is usually done
of the following methods: reverse osmosis or
distillation. Reverse osmosis is where salt water
is forced against a filter. The filter has
extremely small openings, so small that only water
can go through it and the salt is left behind.
Try looking up osmosis in a biology textbook.
Desalination uses the reverse process, so it takes
a lot of energy to force this to happen.
water is distilled, it is boiled and the steam is
collected. Since steam is just water that's been
turned into a gas, if you cool it down, it reforms
water. Salt doesn't get carried away with the
water, so you get pure water. You may have seen
this if you've made pasta with salt water and left
it too long. All of the salt is left in the pot
and the water is evaporated. If you could collect
the steam from the pot, it wouldn't be
Both forms of desalination take a lot of
energy (usually in the form of electricity) so it
is very expensive to produce drinking water with
them. This is the largest con. Santa Barbara
actually has a reverse osmosis desalination plant,
but it isn't used because it makes the water too
expensive to buy - it's for emergency use only.
The benefit is that if you have a vast supply of
cheap renewable energy, there is a huge body of
water- the ocean - that we can draw water for